Number 26
Printed in U.S.A. 90-861329--1 MARCH 1999
1999, Mercury Marine
MARINE ENGINES
SERVICE
MANUAL
GM 4 Cylinder 181 cid (3.0L)
MAIN MENU
MerCruiser # 26 GM 4 Cylinder 181 cid (3.0L)
90-861329--1
MerCruiser # 26 GM 4 Cylinder 181 cid (3.0L)
90-861329--1
90-861329--1 MARCH 1999 Page i
Notice
Throughout this publication, “Dangers”, “Warnings” and “Cautions” (accompanied by the In-
ternational HAZARD Symbol
) are used to alert the mechanic to special instructions con-
cerning a particular service or operation that may be hazardous if performed incorrectly or
carelessly. OBSERVE THEM CAREFULLY!
These “Safety Alerts” alone cannot eliminate the hazards that they signal. Strict compliance
to these special instructions when performing the service, plus “Common Sense” operation,
are major accident prevention measures.
DANGER
DANGER - Immediate hazards which WILL result in severe personal injury or death.
WARNING
WARNING - Hazards or unsafe practices which COULD result in severe personal in-
jury or death.
CAUTION
Hazards or unsafe practices which could result in minor personal injury or product
or property damage.
Notice to Users of This Manual
This service manual has been written and published by the Service Department of Mercury
Marine to aid our dealers’ mechanics and company service personnel when servicing the
products described herein.
It is assumed that these personnel are familiar with the servicing procedures of these prod-
ucts, or like or similar products manufactured and marketed by Mercury Marine, that they
have been trained in the recommended servicing procedures of these products which in-
cludes the use of mechanics’ common hand tools and the special Mercury Marine or recom-
mended tools from other suppliers.
We could not possibly know of and advise the service trade of all conceivable procedures
by which a service might be performed and of the possible hazards and/or results of each
method. We have not undertaken any such wide evaluation. Therefore, anyone who uses
a service procedure and/or tool, which is not recommended by the manufacturer, first must
completely satisfy himself that neither his nor the products safety will be endangered by the
service procedure selected.
All information, illustrations and specifications contained in this manual are based on the
latest product information available at the time of publication. As required, revisions to this
manual will be sent to all dealers contracted by us to sell and/or service these products.
It should be kept in mind, while working on the product, that the electrical system and ignition
system are capable of violent and damaging short circuits or severe electrical shocks. When
performing any work where electrical terminals could possibly be grounded or touched by
the mechanic, the battery cables should be disconnected at the battery.
Any time the intake or exhaust openings are exposed during service they should be covered
to protect against accidental entrance of foreign material which could enter the cylinders and
cause extensive internal damage when the engine is started.
Index
Page ii 90-861329--1 MARCH 1999
It is important to note, during any maintenance procedure replacement fasteners must have
the same measurements and strength as those removed. Numbers on the heads of the met-
ric bolts and on the surfaces of metric nuts indicate their strength. American bolts use radial
lines for this purpose, while most American nuts do not have strength markings. Mis-
matched or incorrect fasteners can result in damage or malfunction, or possibly personal
injury. Therefore, fasteners removed should be saved for reuse in the same locations when-
ever possible. Where the fasteners are not satisfactory for re-use, care should be taken to
select a replacement that matches the original.
We reserve the right to make changes to this manual without prior notification.
Refer to dealer service bulletins for other pertinent information concerning the products de-
scribed in this manual.
Engine Mechanical Components
Many of the engine mechanical components are designed for marine applications. Unlike
automotive engines, marine engines are subjected to extended periods of heavy load
and wide-open-throttle operation and, therefore, require heavy-duty components. Special
marine engine parts have design and manufacturing specifications which are required to
provide long life and dependable performance. Marine engine parts also must be able to
resist the corrosive action of salt or brackish water that will rust or corrode standard automo-
tive parts within a short period of time.
Failure to use recommended Quicksilver service replacement parts can result in poor en-
gine performance and/or durability, rapid corrosion of parts subjected to salt water and
possibly complete failure of the engine.
Use of parts other than recommended service replacement parts, will void the warranty on
those parts which are damaged as a result of the use of other than recommended replace-
ment parts.
Replacement Parts
WARNING
Electrical, ignition and fuel system components on MerCruiser Engines and Stern
Drives are designed and manufactured to comply with U.S. Coast Guard Rules
and Regulations to minimize risks of fire or explosion.
Use of replacement electrical, ignition or fuel system components, which do not
comply to these rules and regulations, could result in a fire or explosion hazard and
should be avoided.
When servicing the electrical, ignition and fuel systems, it is extremely important
that all components are properly installed and tightened. If not, any electrical or ig-
nition component opening would permit sparks to ignite fuel vapors from fuel sys-
tem leaks, if they existed.
Models Covered in This Manual
Model Serial Number Model Year
MCM 3.0L Alpha OL010042 and Above 1998 -
Index
1
2
3
4
5
6
7
8
Important Information
Removal And Installation
Engine
Electrical System
Fuel System
Cooling System
Exhaust System
Power Steering
90-861329--1 MARCH 1999 Page iii
Service Manual Outline
Section 1 - Important Information
A - General Information
B - Maintenance
C - Troubleshooting
Section 2 - Removal and Installation
A - MCM 3.0L (181 CID) - Alpha Drive
Section 3 - Engine
A - 3.0L (181 CID)
Section 4 - Electrical System
A - Starting System
B - Ignition System
C - Charging System
D - Instrumentation
E - Wiring Diagrams
Section 5 - Fuel System
A - Fuel Pump
B - MerCarb 2-Barrel
Section 6 - Cooling System
A - Seawater Cooled Models
B - Closed Cooled Models
Section 7 - Exhaust System
A - Exhaust Manifolds / Elbows
Section 8 - Power Steering
A - Power Steering
Index
Page iv 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
Index
1
A
GENERAL INFORMATION
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1A-1
IMPORTANT INFORMATION
Section 1A - General Information
Table of Contents
Table of Contents 1A-1. . . . . . . . . . . . . . . . . . . . .
Introduction 1A-2. . . . . . . . . . . . . . . . . . . . . . . . . . .
How to Use This Manual 1A-2. . . . . . . . . . . . . . .
Page Numbering 1A-2. . . . . . . . . . . . . . . . . . .
How to Read a Parts Manual 1A-3. . . . . . . . . . .
Directional References 1A-4. . . . . . . . . . . . . . . . .
Engine Rotation 1A-4. . . . . . . . . . . . . . . . . . . . . . .
Engine Serial Number Locations 1A-5. . . . . . . .
Propeller Information 1A-5. . . . . . . . . . . . . . . . . .
Water Testing New Engines 1A-6. . . . . . . . . . . .
Boat and Engine Performance 1A-6. . . . . . . . . .
Boat Bottom 1A-6. . . . . . . . . . . . . . . . . . . . . . .
Marine Fouling 1A-8. . . . . . . . . . . . . . . . . . . . .
Weight Distribution 1A-9. . . . . . . . . . . . . . . . . .
Water in Boat 1A-9. . . . . . . . . . . . . . . . . . . . . .
Elevation and Climate 1A-9. . . . . . . . . . . . . . .
Index
GENERAL INFORMATION SERVICE MANUAL NUMBER 26
Page 1A-2 90-861329--1 MARCH 1999
Introduction
This comprehensive overhaul and repair manual is designed as a service guide for the mod-
els previously listed. It provides specific information, including procedures for disassembly,
inspection, assembly and adjustment to enable dealers and service mechanics to repair and
tune these engines.
Before attempting repairs or tune-up, it is suggested that the procedure first be read through
to gain knowledge of the methods and tools used and the cautions and warnings required
for safety.
How to Use This Manual
This manual is divided into sections which represent major components and systems.
Some sections are further divided into parts which more fully describe the component.
Sections and section parts are listed on the “Service Manual Outline” page following “V-8
Models Covered in This Manual” page.
Page Numbering
Two number groups appear at the bottom of each page. Following is an example and
description.
a
b
c
d
e
f
g
a-Section Number
b-Section Part
c-Page Number
d-Manual Part Number
e-Revision Number
f-Month Printed
g-Year Printed
Index
GENERAL INFORMATION
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1A-3
How to Read a Parts Manual
POWER STEERING PUMP ASSEMBLY
1
2
3
4
5
6
7
8
9
10
REF.
NO.
PART NO. SYM. QTY. DESCRIPTION
1
90507A12 1 PUMP ASSEMBLYPower Steering
2
36- 95805 1 CAP
3
73873A1 1 PULLEY
4
16- 41877 1 STUD
5
57- 65607T 1 V-BELT
6
32- 806684 1 HOSEPressure (FITTINGS ON BOTH ENDS)
7
25- 89879 1 O-RING
8
25- 806232 1 O-RING
9
13- 35048 1 LOCKWASHER (3/8 in.)
10
61990 1 CABLE TIE
REF. NO. : Number shown next to part on exploded view
PART NO. : Mercury Part Number for ordering. If NSS (not sold separately) sometimes GM
part number will be given in description column.
QTY. : The quantity that must be ordered.
DESCRIPTION : Description of part, what parts are included with a part (all indented items
come with the main item above the indented parts), serial number information, and special
information.
Index
GENERAL INFORMATION SERVICE MANUAL NUMBER 26
Page 1A-4 90-861329--1 MARCH 1999
Directional References
Front of boat is bow; rear is stern. Starboard side is right side; port side is left side. In this
maintenance manual, all directional references are given as they appear when viewing boat
from stern looking toward bow.
72000
STARBOARD
(RIGHT)
PORT
(LEFT)
FORE or BOW
(FRONT)
AFT or STERN
(REAR)
Engine Rotation
Engine rotation is determined by observing flywheel rotation from the rear (stern end) of the
engine looking forward (toward water pump end). Propeller rotation is not necessarily the
same as engine rotation. When ordering replacement engine, short blocks or parts for
engine, be certain to check engine rotation. Do not rely on propeller rotation in determining
engine rotation.
72001
Standard Left Hand Rotation
Index
GENERAL INFORMATION
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1A-5
Engine Serial Number Locations
71559
a
b
a-Serial Number Plate
b-Starter Motor
Propeller Information
Refer to the “Propeller” section in appropriate MerCruiser Sterndrive Service Manual, or
order publication 90-86144, What You Should Know About Quicksilver Propellers.
Changing diameter, pitch or coupling of a propeller will affect engine rpm and boat perfor-
mance. The blade configuration also will affect performance. Two like propellers, same pitch
and diameter, from two different manufacturers also will perform differently.
It is the responsibility of the boat manufacturer and/or selling dealer to equip the boat with
the correct propeller to allow the engine to operate within its specified rpm range at
wide-open-throttle (W.O.T.).
Because of the many variables of boat design and operation, only testing will determine the
best propeller for the particular application.
To test for correct propeller, operate boat (with an average load onboard) at W.O.T. and
check rpm with an accurate tachometer. Engine rpm should be near top of the specified
range so that, under heavy load, engine speed will not fall below specifications.
If engine exceeds the specified rpm, an increase in pitch and/or diameter is required.
If engine is below rated rpm, a decrease in pitch and/or diameter is required.
Normally, a change of approximately 400 rpm will be achieved for each single pitch change
of a propeller.
CAUTION
If a propeller is installed that does not allow engine rpm to reach the specified
full-throttle rpm range, the engine will “labor” and will not produce full power.
Operation under this condition will cause excessive fuel consumption, engine
overheating and possible piston damage (due to detonation). On the other hand,
installation of a propeller that allows engine to run above the specified rpm limit will
cause excessive wear on internal engine parts which will lead to premature engine
failure.
Index
GENERAL INFORMATION SERVICE MANUAL NUMBER 26
Page 1A-6 90-861329--1 MARCH 1999
Water Testing New Engines
Use care during the first 20 hours of operation on new MerCruiser engines or possible
engine failure may occur. If a new engine has to be water-tested at full throttle before the
break-in period is complete, follow this procedure.
1. Start engine and run at idle rpm until normal operating temperature is reached.
2. Run boat up on plane.
3. Advance engine rpm (in 200 rpm increments) until engine reaches its maximum rated
rpm.
IMPORTANT: Do not run at maximum rpm for more than 2 minutes.
Boat and Engine Performance
Boat Bottom
For maximum speed, a boat bottom should be as flat as possible in a fore-aft direction
(longitudinally) for approximately the last 5 ft (1.5 m).
72002
a
a-Critical Bottom Area
Index
GENERAL INFORMATION
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1A-7
For best speed and minimum spray, the corner between the bottom and the transom should
be sharp.
72003
a
b
c
a-Bottom
b-Corner
c-Transom
The bottom is referred to as having a hook if it is concave in the fore-and-aft direction. A
hook causes more lift on the bottom near the transom and forces the bow to drop. This
increases wetted surface and reduces boat speed. A hook, however, aids in planing and
reduces any porpoising (rhythmical bouncing) tendency. A slight hook is often built in by the
manufacturer. A hook also can be caused by incorrect trailering or storing the boat with
support directly under the transom.
72004
a
a-Hook
A rocker is the reverse of a hook. The bottom is convex or bulged in the fore-and-aft direc-
tion. It can cause the boat to porpoise.
72005
a
a-Rocker
Any hook, rocker or surface roughness on the bottom, particularly in the all-important
center-aft portion will have a negative effect on speed, often several miles per hour on a fast
boat.
Index
GENERAL INFORMATION SERVICE MANUAL NUMBER 26
Page 1A-8 90-861329--1 MARCH 1999
Marine Fouling
Fouling is an unwanted build-up (usually animal-vegetable-derived) occurring on the boat’s
bottom and drive unit. Fouling adds up to drag, which reduces boat performance. In fresh
water, fouling results from dirt, vegetable matter, algae or slime, chemicals, minerals and
other pollutants. In salt water, barnacles, moss and other marine growth often produce
dramatic build-up of material quickly. Therefore, it is important to keep the hull as clean as
possible in all water conditions to maximize boat performance.
Antifouling paint, if required, may be applied to boat hull observing the following precautions.
IMPORTANT: DO NOT paint anodes or MerCathode System reference electrode and
anode, as this will render them ineffective as galvanic corrosion inhibitors.
CAUTION
Avoid corrosion damage. Do not apply antifouling paint to MerCruiser drive unit or
transom assembly.
IMPORTANT: If antifouling protection is required, Tri-Butyl-Tin-Adipate (TBTA) base
antifouling paints are recommended on MerCruiser boating applications. In areas
where Tri-Butyl-Tin-Adipate base paints are prohibited by law, copper base paints
can be used on boat hull and boat transom. Corrosion damage that results from the
improper application of antifouling paint will not be covered by the limited warranty.
Observe the following:
Avoid an electrical interconnection between the MerCruiser Product, Anodic Blocks,
or MerCathode System and the paint by allowing a minimum of 1 in. (26mm)
UNPAINTED area on transom of the boat around these items.
71176
a
b
a-Antifouling Paint
b-MINIMUM 1 inch (26 mm) Unpainted Area
Index
GENERAL INFORMATION
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1A-9
Weight Distribution
Weight distribution is extremely important; it affects a boats running angle or attitude. For
best top speed, all movable weight - cargo and passengers - should be as far aft as possible
to allow the bow to come up to a more efficient angle (3 to 5 degrees). On the negative side
of this approach is the problem that, as weight is moved aft, some boats will begin an unac-
ceptable porpoise.
Secondly, as weight is moved aft, getting on plane becomes more difficult.
Finally, the ride in choppy water becomes more uncomfortable as the weight goes aft. With
these factors in mind, each boater should seek out what weight locations best suit his/her
needs.
Weight and passenger loading placed well forward increases the wetted area of the boat
bottom and, in some cases, virtually destroys the good performance and handling charac-
teristics of the boat. Operation in this configuration can produce an extremely wet ride, from
wind-blown spray, and could even be unsafe in certain weather conditions or where bow
steering may occur.
Weight distribution is not confined strictly to fore and aft locations, but also applies to lateral
weight distribution. Uneven weight concentration to port or starboard of the longitudinal
centerline can produce a severe listing attitude that can adversely affect the boats
performance, handling ability and riding comfort. In extreme rough water conditions, the
safety of the boat and passengers may be in jeopardy.
Water in Boat
When a boat loses performance, check bilge for water. Water can add considerable weight
to the boat, thereby decreasing the performance and handling.
Make certain that all drain passages are open for complete draining.
Elevation and Climate
Elevation has a very noticeable effect on the wide-open-throttle power of an engine. Since
air (containing oxygen) gets thinner as elevation increases, the engine begins to starve for
air. Humidity, barometric pressure and temperature do have a noticeable effect on the
density of air. Heat and humidity thin the air. This phenomenon can become particularly
apparent when an engine is propped out on a cool dry day in spring and later, on a hot, humid
day in August, does not have the same performance.
Although some performance can be regained by dropping to a lower pitch propeller, the
basic problem still exists. The propeller is too large in diameter for the reduced power output.
A Quicksilver Propeller Repair Station or experienced marine dealer can determine how
much diameter to remove from a lower-pitch propeller for specific high-elevation locations.
In some cases, installing high altitude gears in the drive unit is possible and very beneficial.
Weather conditions may effect the power output of internal combustion engines. Therefore,
established horsepower ratings refer to the power that the engine will produce at its rated
rpm under a specific combination of weather conditions.
Index
GENERAL INFORMATION SERVICE MANUAL NUMBER 26
Page 1A-10 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
Index
1
B
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-1
IMPORTANT INFORMATION
Section 1B - Maintenance
Table of Contents
Maintenance Schedule 1B-2. . . . . . . . . . . . . . . . .
Maintenance Intervals 1B-2. . . . . . . . . . . . . . .
Scheduled Maintenance That Can
Be Performed By Owner/Operator 1B-2. . .
Scheduled Maintenance That Should
Be Performed By A Dealer 1B-3. . . . . . . . . .
Engine and Tune-Up Specifications 1B-4. . . . . .
Fluid Capacities 1B-5. . . . . . . . . . . . . . . . . . . . . . .
Engine Rotation and Firing Order 1B-5. . . . . . . .
L.H. Rotation Front 1B-5. . . . . . . . . . . . . . . . .
20-Hour Break-In Period 1B-5. . . . . . . . . . . . . . .
After Break-in Period 1B-6. . . . . . . . . . . . . . . . . .
End of First Season Checkup 1B-6. . . . . . . . . . .
Fuel 1B-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Ratings 1B-6. . . . . . . . . . . . . . . . . . . . . . .
General Information 1B-6. . . . . . . . . . . . . . . . .
Gasoline / Alcohol Blends 1B-7. . . . . . . . . . . .
Effects of Gasoline / Alcohol Blends
on Marine Engines 1B-7. . . . . . . . . . . . . . . . .
Boat / Motor Storage 1B-8. . . . . . . . . . . . . . . .
Winter Storage 1B-8. . . . . . . . . . . . . . . . . . . . .
Warranty 1B-8. . . . . . . . . . . . . . . . . . . . . . . . . .
Continuing Evaluations 1B-8. . . . . . . . . . . . . .
Test For Alcohol Content In Gasoline 1B-8. .
Crankcase Oil 1B-9. . . . . . . . . . . . . . . . . . . . . . . .
Overfilled Crankcase Oil 1B-9. . . . . . . . . . . . .
Adding Crankcase Oil 1B-10. . . . . . . . . . . . . .
Checking Engine Oil Level/Filling 1B-10. . . .
Changing Oil and Filter 1B-11. . . . . . . . . . . . . . . .
Priming Engines With Oil 1B-11. . . . . . . . . . . . . .
Tools Required 1B-11. . . . . . . . . . . . . . . . . . . .
Procedure 1B-11. . . . . . . . . . . . . . . . . . . . . . . .
Power Steering System 1B-12. . . . . . . . . . . . . . .
Checking Fluid Level 1B-12. . . . . . . . . . . . . . .
Filling and Bleeding 1B-13. . . . . . . . . . . . . . . .
Closed Cooling System 1B-14. . . . . . . . . . . . . . .
Checking Coolant Level 1B-14. . . . . . . . . . . .
Coolant for Closed Cooling System 1B-14. .
Flushing System 1B-15. . . . . . . . . . . . . . . . . . .
Lubrication 1B-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Cable 1B-17. . . . . . . . . . . . . . . . . . . . .
Shift Cable 1B-18. . . . . . . . . . . . . . . . . . . . . . . .
Engine Coupler / U-Joint Shaft
Splines 1B-18. . . . . . . . . . . . . . . . . . . . . . . . . .
Cold Weather or Extended Storage 1B-19. . . . .
Precautions 1B-19. . . . . . . . . . . . . . . . . . . . . . .
Power Package Layup 1B-20. . . . . . . . . . . . .
Draining Instructions 1B-21. . . . . . . . . . . . . . . . . .
Single Point Drain System 1B-21. . . . . . . . . .
Draining Seawater (Raw-Water)
Cooled Models 1B-23. . . . . . . . . . . . . . . . . . .
Draining Seawater Section of Closed
Cooled (Coolant) Models 1B-26. . . . . . . . . .
Recommissioning 1B-28. . . . . . . . . . . . . . . . . .
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-2 90-861329--1 MARCH 1999
Maintenance Schedule
Maintenance Intervals
Maintenance intervals and the tasks to be performed, as shown in this current schedule, or
as found in previously printed schedules, are generally based on an average boating
application and environment. However, individual operating habits and personal mainte-
nance preferences can have an impact on the suggested intervals. In consideration of these
factors, MerCruiser has adjusted some maintenance intervals and corresponding tasks to
be performed. In some cases, this may allow for more individual tasks to be performed in
a single visit to the servicing dealer, rather than multiple visits. Therefore, it is very important
that the boat owner and servicing dealer discuss the current Maintenance Schedule and
develop appropriate maintenance intervals to coincide with the individual operating habits,
environment and maintenance requirements.
Scheduled Maintenance That Can Be Performed By Owner/Operator
NOTE: Only perform maintenance which applies to your particular power package.
Task
Interval
Engine Crankcase Oil - Check level.
Closed Cooling Coolant - Check level.
Power Steering Fluid - Check level.
Sterndrive Unit Oil - Check level.
Battery - Check level and inspect for
damage.
Fuel Pump Sight Tube (If Equipped) - Check
that no fuel is present.
Weekly
Power Trim Pump Oil - Check level.
Anodes - Inspect for erosion.
Gear Housing Water Pickups - Check for
marine growth or debris.
Drive Belts (All) - Inspect condition and
check tension.
Every 100 hours of operation or 120 days,
whichever occurs first.
Propeller Shaft - Lubricate.
Saltwater Use: Every 50 hours of operation
or 60 days, whichever occurs first.
Power Package Exterior Surfaces - Spray
with rust preventative.
Freshwater Use: Every 100 hours of
operation or 120 days, whichever occurs
first.
Power Package Exterior Surfaces - Clean
and paint.
Once a year
Cooling System - Flush seawater section. Saltwater Use: After every use.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-3
Scheduled Maintenance That Should Be Performed By A Dealer
NOTE: Only perform maintenance which applies to your particular power package.
Task
Interval
Seawater Pickup Pump - Disassemble and
inspect.
Whenever insufficient seawater flow is
suspected (if operating temperature
exceeds normal range.)
Crankcase Oil and Filter - Change.
Ignition System - Clean and inspect
condition.
Flame Arrestor and Crankcase Ventilation
Hose - Clean and inspect.
Positive Crankcase Ventilation (PCV) Valve
(If Equipped) - Change.
Sterndrive Unit Oil - Change.
Gimbal Ring Clamping Screws - Retorque
to 50-55 lb-ft (67-74 Nm).
Rear Engine Mounts - Check, torque to
38 lb-ft (52 Nm).
Gimbal Bearing - Lubricate.
Cooling System - Clean and inspect.
Steering System - Lubricate and inspect for
loose, damaged or missing parts.
End of first boating season and thereafter,
Electrical System - Check for loose or
damaged wiring.
every 100 hours of operation or once yearly,
whichever occurs first.
Closed Cooling System Pressure Cap -
Clean, inspect and test.
Cooling System Hoses and Clamps -
Inspect for damage and deterioration.
Check clamps for tightness.
Continuity Circuit - Check components for
loose connections, broken or frayed wires.
Shift and Throttle Cable and Linkage -
Lubricate and inspect for loose, damaged or
missing parts.
Engine Exhaust System - Inspect externally
for damage, deterioration and restrictions.
Check for tightness.
Ignition System - Check timing and adjust
as needed.
Closed Cooling Coolant - Replace.
Every 5 years or 1000 hours, whichever
occurs first
1
1
Only if Extended Life 5/100 Ethylene Glycol Antifreeze/Coolant is used. If any non-compatible coolant is added
to this coolant, coolant must be changed every 2 years or 400 hours, whichever occurs first. All coolants other
than Extended Life 5/100 Ethylene Glycol Antifreeze/Coolant must be changed every 2 years or 400 hours,
whichever occurs first.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-4 90-861329--1 MARCH 1999
Engine and Tune-Up Specifications
MODEL MCM 3.0L
Propshaft Horsepower
(SAV1 Rating)
135
1
(114
2
)
Propshaft Kilowatts
(SAV1 Rating)
101
1
(85
2
)
Number of Cylinders 4
Displacement 181 cid (3.0L)
Bore/Stroke In. (mm) 4.00 X 3.60 (101.6 X 91.4)
Compression Ratio 9.25:1
Compression Pressure Minimum 100 psi (690 kPa)
7
Idle rpm (In Neutral)
3
700 rpm
5
Max rpm (At W.O.T.)
3
4400-4800 rpm
Oil Pressure (at 2000 rpm) Minimum 30 psi (207 kPa)
Fuel Pump psi (At 1000 rpm) 6-8 psi (41-55 kPa)
Minimum Oil Pressure At Idle 4 psi (28 kPa)
Electrical System 12 Volt Negative (-) Ground
Minimum Battery Requirements 375 cca / 475 mca / 90 Ah
Firing Order 1-3-4-2
Spark Plug Type
AC - MR43LTS
Champion - RS12YC
NGK - BPR6EFS
Spark Plug Gap .035 in. (0.9 mm)
Timing (At Idle)
4
1° BTDC
8
/ 1° ATDC
9
/ 2° ATDC
10
Preliminary Idle Mixture 1 1/4 Turns
Thermostat 143° F (62° C)
8
/ 160° F(71° C)
10
1
Power Rated in Accordance with NMMA (National Marine Manufacturers’ Association) rating procedures.
2
Power Rated in Accordance with SAV1 rating procedures. This rating procedure is used to certify that the en-
gine complies with “Stage 1” Bodensee and Swiss Regulations. Horsepower differences shown result from dif-
ferences in test rpm, allowable test tolerances, and/or installation of special kit components.
3
Measured using an accurate service tachometer with engine at normal operating temperature.
4
Timing must be set using a special procedure as outlined in the appropriate section of this manual. Timing can-
not be properly set using the conventional method.
5
A special procedure must be followed to adjust idle rpm. Consult your Authorized MerCruiser Dealer before
attempting this procedure.
7
Minimum recorded compression in any one cylinder should not be less than 70 percent of the highest recorded
cylinder.
8
Serial number break: 0L096999 and below
9
Serial number break: 0L097000 - 0L0340999
10
Serial number break: 0L341000 and above.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-5
Fluid Capacities
NOTICE
Unit Of Measurement: U.S. Quarts (Liters)
All capacities are approximate fluid measures.
MODEL MCM 181 cid / 3.0L
Crankcase (With Filter)
1
4 (3.8)
Seawater Cooling System
2
9 (8.5)
Closed Cooling System 9 (8.5)
1
Always use dipstick to determine exact quantity of oil or fluid required.
2
Seawater Cooling System capacity information is for winterization use only.
Engine Rotation and Firing Order
L.H. Rotation Front
50683
4 Cylinder - 181 cid / 3.0L Firing Order 1-3-4-2
20-Hour Break-In Period
IMPORTANT: The first 20 hours of operation is the engine break-in period. Correct
break-in is essential to obtain minimum oil consumption and maximum engine per-
formance. During this break-in period, the following rules must be observed:
Do not operate below 1500 rpm for extended periods of time for first 10 hours. Shift into
gear as soon as possible after starting and advance throttle above 1500 rpm if condi-
tions permit safe operation.
Do not operate at one speed consistently for extended periods.
Do not exceed 3/4 throttle during first 10 hours. During next 10 hours, occasional
operation at full throttle is permissible (5 minutes at a time maximum).
Avoid full throttle acceleration from IDLE speed.
Do not operate at full throttle until engine reaches normal operating temperature.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-6 90-861329--1 MARCH 1999
After Break-in Period
To help extend the life of your MerCruiser power package, the following recommendations
should be considered;
Use a propeller that allows the engine to operate at or near the top of the maximum rpm
range (See “Specifications” section) when at full throttle with a normal boat load.
Operation at 3/4 throttle setting or lower is recommended. Refrain from prolonged
operation at maximum (full throttle) rpm.
End of First Season Checkup
At the end of the first season of operation, an Authorized MerCruiser Dealer should be con-
tacted to discuss and/or perform various scheduled maintenance items. If you are in an area
where the product is operated continuously (year-round operation), you should contact your
dealer at the end of the first 100 hours of operation, or once yearly, whichever occurs first.
Fuel
Fuel Ratings
CAUTION
Use of improper gasoline can damage the engine seriously. Engine damage that
results from use of improper gasoline is considered misuse of the engine and is not
covered under MerCruiser Warranty.
USA AND CANADA
Fuel having a posted pump Octane Rating of 87 (R + M) / 2 minimum. Premium gasoline
[90 (R + M) / 2] is also acceptable. DO NOT use leaded gasolines.
OUTSIDE USA AND CANADA
Fuel having a posted pump Octane Rating of 90 RON minimum. Premium gasoline (98
RON) is also acceptable. If unleaded is not available, use a major brand of leaded gasoline.
General Information
Gasolines containing alcohol, either methyl alcohol (methanol) or ethyl alcohol (ethanol)
may cause increased:
Corrosion of metal parts.
Deterioration of elastomer and plastic parts.
Fuel permeation through flexible fuel lines.
Wear and damage of internal engine parts.
Starting and operating difficulties.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-7
Some of these adverse effects are due to the tendency of gasolines containing alcohol to
absorb moisture from the air, resulting in a phase of water and alcohol separating from the
gasoline in the fuel tank.
The adverse effects of alcohol are more severe with methyl alcohol (methanol) and are
worse with increasing alcohol content.
WARNING
Fire and Explosion Hazard: Fuel leakage from any part of the fuel system can be a
fire and explosion hazard which can cause serious bodily injury or death. Careful
periodic inspection of the entire fuel system is mandatory, particularly after
storage. All fuel system components including fuel tanks (whether plastic, metal or
fiberglass), fuel lines, primer bulbs, fittings, fuel filters and carburetors should be
inspected for leakage, softening, hardening, swelling or corrosion. Any sign of
leakage or deterioration requires replacement before further engine operation.
Because of possible adverse effects of alcohol in gasoline, it is recommended that
only alcohol-free gasoline be used where possible. If only fuel containing alcohol
is available, or if the presence of alcohol is unknown, increased inspection
frequency for leaks and abnormalities is required.
WARNING
Avoid gasoline fire or explosion. Improper installation of brass fittings or plugs into
fuel pump or fuel filter base can crack casting and/or cause a fuel leak.
IMPORTANT: When operating a MerCruiser engine on gasoline containing alcohol,
storage of gasoline in the fuel tank for long periods should be avoided. Long periods
of storage, common to boats, create unique problems. In cars, alcohol-blend fuels
normally are consumed before they can absorb enough moisture to cause trouble,
but boats often sit idle long enough for phase separation to take place. In addition,
internal corrosion may take place during storage if alcohol has washed protective oil
films from internal components.
Gasoline / Alcohol Blends
Many new motor vehicle owner manuals are warning about the potential damage from using
gasoline containing alcohol, especially METHANOL. They cite possible fuel system
damage and performance problems. These are just two of the hazards that may be caused
by alcohol. These same problems as well as the additional safety risk of fire and explosion
from fuel system leaks apply to marine inboard engines. METHANOL is more severe in its
bad effect than is ETHANOL. Alcohol is also more severe in older engines since newer
engines have materials which are more resistant to alcohol.
Effects of Gasoline / Alcohol Blends on Marine Engines
Corrosion of metals may result from use of alcohol-gasoline blends. Portable or
permanently installed fuel tanks of metal or fiberglass, fuel filters, fuel lines and float bowls
may be affected by alcohol blended fuels. Many fiberglass fuel tanks are slowly dissolved
by alcohol, leading immediately to filter and carburetor plugging and eventually to tank
failure.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-8 90-861329--1 MARCH 1999
Fuels containing alcohol will absorb moisture from the air. At first, this moisture will remain
in solution, but once the water content of the fuel has built up to about one-half of one
percent, it will separate out (phase separation), bringing the alcohol with it. This
alcohol-water mixture settles to the bottom of the fuel tank and if this mixture gets into the
engine, the engine can be seriously damaged internally, as it may wash the protective film
of oil off the bore of any cylinder that it enters. Before the engine can be restarted, it is
necessary to remove the separated alcohol and water layer, flush out the fuel system with
clean fuel and remove and dry the spark plugs.
Boat / Motor Storage
When operating a MerCruiser engine on gasoline containing alcohol, storage of gasoline
in the fuel tank for long periods of time should be avoided.
Long periods of storage, common to boats, create unique problems. In cars,
gasoline/alcohol blend fuels normally are consumed before they can absorb enough
moisture to cause trouble, but boats often sit idle long enough for phase separation to take
place. In addition, internal corrosion may take place during storage if alcohol has washed
protective oil films from internal components.
Winter Storage
If boat is to be placed in winter storage, carburetors must be run dry at idle rpm. Permanent
fuel tanks should be drained completely and Quicksilver Gasoline Stabilizer and
Conditioner added to any fuel remaining in the tank. Portable fuel tanks should be emptied
completely.
Warranty
Performance problems and fuel system or other damage resulting from the use of
gasoline-alcohol blended fuels are not the responsibility of MerCruiser and will not be
covered under our warranty.
Continuing Evaluations
The effects of gasoline with ETHANOL and METHANOL are still being evaluated by the
United States Coast Guard, the National Marine Manufacturers Association (NMMA),
Mercury Marine and other engine and boat manufacturers.
We have recommended pump posting of alcohol content of gasoline. Further we recom-
mend using gasoline known not to contain any METHANOL or ETHANOL when possible.
Test For Alcohol Content In Gasoline
The following is an acceptable and widely used field procedure for the detection of alcohol
in gasoline. Use any small transparent bottle or tube that can be capped and is, or can be,
provided with graduations or a mark at about 1/3 full. A pencil mark on a piece of adhesive
tape may be used.
PROCEDURE
1. Fill the container with water to the mark.
2. Add fuel almost to fill the container, leaving some air space, then cap the container. The
proportions of fuel to water are not critical, but there should be 2 to 3 times as much fuel
as water.
3. Shake container vigorously and allow it to sit upright for 3 to 5 minutes. If the volume
of water appears to have increased, alcohol is present. If you are not sure, there is no
need for concern. If the dividing line between water and fuel becomes cloudy, use the
middle of the cloudy band.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-9
Crankcase Oil
To help obtain optimum engine performance and to provide maximum protection, we
strongly recommend the use of Quicksilver 4-Cycle 25W-40 Marine Engine Oil. This oil is
a special blend of 25-weight and 40-weight oils for marine engines. If not available, a good
grade, straight weight, detergent automotive oil of correct viscosity, with an API service
rating of SH,CF/CF-2 may be used.
In those areas where Quicksilver 4-Cycle 25W-40 Marine Engine Oil or a recommended
straight weight oil is not available, a multi-viscosity 20W-40 or, as a second but less
preferable choice, 20W-50, with API service ratings of SH,CF/CF-2 may be used.
IMPORTANT: The use of non-detergent oils, multi-viscosity oils (other than
Quicksilver 25W-40 or a good quality 20W-40 or 20W-50), synthetic oils, low quality
oils or oils that contain solid additives are specifically not recommended.
The chart below is a guide to crankcase oil selection. The oil filter should always be changed
with the engine oil.
SAE 20W
SAE 30W
SAE 40W
32° F
0
° C
50
° F
10
° C
AIR TEMPERATURE
75796
Overfilled Crankcase Oil
Overfilled crankcases (oil level being too high ) can cause a fluctuation or drop in oil pressure
and rocker arm clatter on MerCruiser engines. The over-full condition results in the engine
crankshaft splashing and agitating the oil, causing it to foam (become aerated). The aerated
oil causes the hydraulic valve lifters to bleed down. This, in turn, results in rocker arm
“clatter” and loss of engine performance, due to the valves not opening properly.
Care must be taken when checking engine oil level. Oil level must be maintained between
the ADD mark and the FULL mark on the dipstick. To ensure that you are not getting a false
reading,” make sure the following steps are done before checking the oil level.
Boat “at rest in the water, or
If boat is on a trailer, raise or lower bow until the boat is setting at the approximate angle
that it would be if setting at rest in the water.
Allow sufficient time for oil to drain into the crankcase if engine has just been run or oil
has just been added.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-10 90-861329--1 MARCH 1999
Adding Crankcase Oil
1. Coat sealing ring on new filter with engine oil, and install. Tighten filter securely
(following filter manufacturers instructions). Do not overtighten.
75809
b
a
a-Oil Filter
b-Sealing Ring
2. Fill crankcase with oil.
3. Start engine and check for leaks.
Checking Engine Oil Level/Filling
IMPORTANT: ENGINE CRANKCASE OIL MUST BE CHECKED AT INTERVALS
SPECIFIED IN “MAINTENANCE SCHEDULE” CHART. It is normal for an engine to use
a certain amount of oil in the process of lubrication and cooling of the engine. The
amount of oil consumption is greatly dependent upon engine speed, with
consumption being highest at wide-open-throttle and decreasing substantially as
engine speed is reduced.
1. Stop engine and allow boat to come to a rest.
2. Allow oil to drain back into oil pan - approximately 5 minutes.
3. Remove dipstick. Wipe clean and reinstall. Push dipstick all the way into dipstick tube.
4. Remove dipstick and note the oil level.
5. Oil level must be between the FULL and ADD marks.
6. If oil level is below ADD mark, proceed to Steps 7 and 8.
7. Remove oil filler cap from valve rocker arm cover.
8. Add required amount of oil to bring level up to, but not over, the FULL mark on dipstick.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-11
Changing Oil and Filter
1. Start engine and run until it reaches normal operating temperatures.
IMPORTANT: Change oil when engine is warm from operation, as it flows more freely,
carrying away more impurities.
2. Stop engine.
3. Remove drain plug from oil pan or from oil drain hose.
NOTE: If drain plug is not accessible because of boat construction, oil may be removed
through dipstick tube, using a Quicksilver Crankcase Oil Pump.
4. After oil has drained completely, reinstall drain plug (if removed) and tighten securely.
5. Remove and discard oil filter and its sealing ring.
Priming Engines With Oil
IMPORTANT: This applies to all power packages that have not been run within 6
months, replacement of partial engines or after rebuilding an engine.
Tools Required
71089
Remote Starter Switch (91-52024A1)
Procedure
1. Fill crankcase to proper level with recommended engine oil.
2. Remove spark plugs.
3. Leave ignition Key in “OFF” position.
4. Connect remote starter switch to large 12V terminal (RED battery cable) and small
terminal (RED/YELLOW) wire on starter motor.
a. If Remote Starter Switch is not available, disconnect PURPLE wire from ignition coil
before using key switch to crank the engine over. Tape terminal on PURPLE wire to
prevent it from touching ground.
5. Crank engine for 15 seconds, then allow starter motor to cool down for 1 minute. This
should prevent starter motor from overheating.
6. Repeat this process until a total of 45 seconds of cranking time is achieved.
7. Remove remote starter switch.
a. If key switch was used, reconnect PURPLE wire to ignition coil.
8. Install spark plugs and wires.
9. Supply cooling water to seawater pump and start motor.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-12 90-861329--1 MARCH 1999
Power Steering System
Checking Fluid Level
ENGINE WARM
1. Stop engine and position drive unit so that it is straight back.
2. Remove fill cap/dipstick from power steering pump and note fluid level.
75809
a
b
a-Fill Cap / Dipstick
b-Power Steering Pump
3. Level should be between the FULL HOT mark and ADD mark on dipstick.
72518
a
a-Proper Fluid Level with Engine Warm
4. If level is below ADD mark, but fluid is still visible in pump reservoir, add required amount
of Quicksilver Power Trim and Steering Fluid or automatic transmission fluid (ATF)
Dexron III through fill cap opening, to bring level up to FULL HOT mark on dipstick. DO
NOT OVERFILL.
5. If fluid is not visible in reservoir, a leak exists in the power steering system. Find cause
and correct.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-13
ENGINE COLD
1. With engine stopped, position drive unit so that it is straight back.
2. Remove fill cap/dipstick from power steering pump and note fluid level.
3. Level should be between FULL COLD mark and bottom of dipstick.
72519
a
a-Proper Fluid Level with Engine Cold
4. If level is below bottom of dipstick, but fluid is still visible in pump reservoir, add required
amount of Quicksilver Power Trim and Steering Fluid or automatic Dexron III
transmission fluid (ATF), through fill cap opening, to bring level up to FULL COLD mark
on dipstick. DO NOT OVERFILL.
If fluid is not visible in reservoir, a leak exists in the power steering system. Find cause and
correct.
Filling and Bleeding
IMPORTANT: Power steering system must be filled exactly as explained in the follow-
ing to be sure that all air is bled from the system. All air must be removed, or fluid in
pump may foam during operation and be discharged from pump reservoir. Foamy
fluid also may cause power steering system to become spongy, which may result in
poor boat control.
1. With engine stopped, position drive unit so that it is straight back. Remove fill
cap/dipstick from power steering pump. Add Quicksilver Power Trim and Steering Fluid
or Dexron III automatic transmission fluid (ATF), as required, to bring level up to FULL
COLD mark on dipstick.
IMPORTANT: Use only Quicksilver Power Trim and Steering Fluid or Dexron IIl auto-
matic transmission fluid (ATF), in power steering system.
2. Turn steering wheel back and forth to end of travel in each direction several times, then
recheck fluid level and add fluid, if necessary.
3. Install vented fill cap.
CAUTION
DO NOT operate engine without water being supplied to seawater pickup pump, or
pump impeller may be damaged and subsequent overheating damage to engine
may result.
4. Start engine and run at fast idle (1000-1500 rpm) until engine reaches normal operating
temperature. During this time, turn steering wheel back and forth to end of travel in each
direction several times.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-14 90-861329--1 MARCH 1999
5. Position drive unit so that it is straight back and stop engine. Remove fill cap from pump.
Allow any foam in pump reservoir to disperse, then check fluid level and add fluid, as
required, to bring level up to FULL HOT mark on dipstick. DO NOT OVERFILL. Reinstall
fill cap securely.
IMPORTANT: Drive unit must be positioned straight back and power steering fluid
must be hot to accurately check fluid level.
6. If fluid is still foamy (in Step 5), repeat Steps 4 and 5 until fluid does not foam and level
remains constant.
Closed Cooling System
Checking Coolant Level
WARNING
Allow engine to cool down before removing pressure cap. Sudden loss of pressure
could cause hot coolant to boil and discharge violently. After engine has cooled,
turn cap 1/4 turn to allow any pressure to escape slowly, then push down and turn
cap all the way off.
1. Coolant level in heat exchanger should be full (to bottom of filler neck).
IMPORTANT: When reinstalling pressure cap, be sure to tighten it until it contacts
stop on filler neck.
2. Coolant level should be between the ADD and FULL marks on coolant recovery
reservoir with the engine at normal operating temperature.
193-HR
a
a-Coolant Recovery Reservoir
Coolant for Closed Cooling System
CAUTION
Alcohol or Methanol base antifreeze or plain water, are not recommended for use
in fresh water section of cooling system at any time.
We recommend that the coolant section of closed cooling system be filled with Extended
Life 5/100 Ethylene Glycol Antifreeze/Coolant. In areas where the possibility of freezing
does not exist, it is permissible to use a solution of rust inhibitor and water (mixed to
manufacturers recommendations).
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-15
Flushing System
If engine is operated in salty, polluted, or mineral-laden water, flush cooling system (prefer-
ably after each use) to reduce corrosion and prevent the accumulation of deposits in the
system. Thoroughly flush cooling system prior to storage.
BOAT OUT OF WATER
WARNING
When flushing cooling system with boat out of the water, be certain that area in
vicinity of propeller is clear and that no person is standing nearby. As a
precautionary measure, it is recommended that propeller be removed.
CAUTION
To prevent engine or sterndrive unit damage DO NOT run engine or drive unit with-
out water being supplied to water intake openings on gear housing, and to seawater
pickup pump if equipped.
1. Connect flushing attachment as follows:
NOTE: If flushing cooling system with boat in water, raise drive unit to trailer position and
install flushing attachment. Lower drive unit to full IN/DOWN position.
a. Install Quicksilver Flushing Attachment (or equivalent) over water intake openings
in gear housing.
b. Connect hose between flushing attachment and water tap.
72012
a
b
a-Quicksilver Flushing Attachment
b-Water Hose
CAUTION
If cooling system is to be flushed with boat in the water, seacock (if equipped) must
be closed, or water inlet hose must be disconnected and plugged to prevent water
from flowing into boat.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-16 90-861329--1 MARCH 1999
2. Partially open water tap(s) (approximately 1/2 maximum capacity) and allow drive unit
and cooling system to fill completely. Do not use full tap water pressure.
72672
a
b
a-Quicksilver Flushing Attachment
b-Water To Drive Unit
NOTE: Drive unit is full when water is discharged out of drive unit, and/or seawater section
of closed cooled system is full when water is discharged through propeller.
CAUTION
Do not run engine above 1500 rpm when flushing. Suction created by seawater pick-
up pump may collapse flushing hose, causing engine to overheat.
3. Place remote control lever in NEUTRAL position and start the engine.
CAUTION
Watch temperature gauge at dash to ensure the engine does not overheat.
4. Operate engine at idle speed in NEUTRAL gear for 10 minutes or until discharge water
is clear, then stop engine.
5. Shut off water tap(s).
6. Remove hose and flushing attachment from drive unit.
BOAT IN WATER
NOTE: If flushing cooling system with boat in water, raise drive unit to trailer position, to
remove flushing attachment. Lower drive unit to full IN/DOWN position after completion.
1. Raise drive unit to full UP (trailer) position.
2. Install flushing attachment over water pickup holes in gear housing as shown.
3. Attach a hose between the flushing attachment and a water tap.
4. Lower drive unit to full IN/DOWN position.
5. Partially open water tap (approximately 1/2 maximum capacity). Do Not use full water
pressure.
6. Place remote control in neutral, idle speed position, and start engine.
7. Operate engine at idle speed in neutral for 10 minutes, the stop engine.
8. Shut off water tap.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-17
9. Raise drive unit to full UP position.
10. Remove hose and flushing attachment.
CAUTION
If boat is in the water, seacock (water inlet valve), if equipped, must remain closed
until engine is to be restarted to prevent water from flowing back into cooling
system and/or boat. If boat is not fitted with a seacock, water inlet hose must be
disconnected and plugged to prevent water from flowing back into cooling system
and/or boat. As a precautionary measure, attach a tag to the ignition switch or
steering wheel of the boat with the warning that the seacock must be opened or the
water inlet hose reconnected prior to starting engine.
a. If equipped with seacock: Observing precaution above, open seacock.
b. If NOT equipped with seacock: Observing precaution above, remove plug from
seawater inlet hose and reconnect seawater inlet hose. Tighten hose clamps
securely.
Lubrication
Lubricate pivot points with SAE 30W motor oil and cable guide contact surfaces with
Quicksilver 2-4-C Marine Lubricant with Teflon.
Throttle Cable
75811
a
a-Pivot Points
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-18 90-861329--1 MARCH 1999
Shift Cable
75811
b
a
b
a-Pivot Points
b-Guide Contact Surface
Engine Coupler / U-Joint Shaft Splines
Lubricate coupler and splines with Quicksilver Engine Coupler Spline Grease
(92-816391A4).
IMPORTANT: Sterndrive unit does not have to be removed to grease coupler.
NOTE: Refer to MerCruiser Sterndrive Service Manual for sterndrive unit removal and
installation if necessary.
72017
b
a
a-Quicksilver Engine Coupler Spline Grease
b-Grease Fitting, Use If Drive Is Installed
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-19
Cold Weather or Extended Storage
Precautions
CAUTION
Sterndrive unit should be stored in full DOWN position. Universal Joint bellows may
develop a set if unit is stored in raised position and may fail when unit is returned
to service.
CAUTION
If Power Package will not be used for an extended period of time or will be exposed
to freezing temperatures, drain water from seawater section of cooling system. Wa-
ter MUST BE drained to prevent corrosion and freeze damage to engine.
CAUTION
If boat is to remain in water after draining, seawater inlet hose must be removed and
plugged. The plug will prevent a siphoning action that may occur, allowing seawater
to flow from the drain holes or removed hoses.
CAUTION
DO NOT operate engine without water flowing through seawater pickup pump, as
pump impeller may be damaged and subsequent overheating damage to engine or
sterndrive unit may result.
CAUTION
Seawater section of cooling system MUST BE COMPLETELY drained for winter
storage, or immediately after cold weather use, if the possibility of freezing temper-
atures exists. Failure to comply may result in trapped water causing freeze and/or
corrosion damage to engine.
IMPORTANT: Observe the following information to ensure complete draining of
cooling system:
Engine must be as level as possible.
A wire should be repeatedly inserted into all drain holes to ensure there are no
obstructions in passages. Remove petcock, if necessary, to insert wire complete-
ly into drain hole.
IMPORTANT: To prevent threads in manifolds, elbows and cylinder blocks from rust-
ing out during storage, reinstall plugs using Quicksilver Perfect Seal on threads.
Never leave drain plugs out during storage.
NOTE: If possible, place a container under drains and hoses to prevent water from draining
into boat.
CAUTION
If engine is equipped with Closed Cooling System, Closed Cooling section must be
kept filled with a solution of ethylene glycol antifreeze and water (mix antifreeze to
manufacturers recommended proportions to protect engine to lowest temperature
to which it will be exposed). DO NOT USE PROPYLENE GLYCOL antifreeze in closed
cooling section. Seawater section, however, must be drained completely.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-20 90-861329--1 MARCH 1999
CAUTION
A discharged battery can be damaged by freezing.
IMPORTANT: MerCruiser recommends that propylene glycol antifreeze (a nontoxic
and environmentally safe) antifreeze be used in seawater section of the cooling sys-
tem for cold weather or extended storage. Make sure that the propylene glycol anti-
freeze contains a rust inhibitor and is recommended for use in marine engines. Be
certain to follow the propylene glycol manufacturers recommendations.
Power Package Layup
CARBURETED MODELS
NOTICE
Refer to Cold Weather or Extended Storage Precautions in this section,
BEFORE proceeding.
1. Follow instructions “a” or “b” depending on type fuel available during layup:
a. If boat is to be placed in storage with fuel in fuel tanks that does not contain
alcohol: Fill fuel tank(s) with fresh gasoline that does not contain alcohol and a
sufficient amount of Quicksilver Gasoline Stabilizer for Marine Engines to treat the
gasoline. Follow instructions on container.
b. If boat is to be placed in storage with fuel in fuel tanks that does contain
alcohol (if fuel without alcohol is unavailable)
: Fuel tanks should be drained as
completely as possible and Quicksilver Gasoline Stabilizer for Marine Engines
added to any fuel remaining in the tank. Follow instructions on container.
IMPORTANT: If boat is to be placed in storage with fuel containing alcohol in fuel
tanks refer to “Fuel” in this SECTION 1B for additional information.
2. Replace the water separating fuel filter as outlined in SECTION 5A - Fuel Delivery
Systems, Water Separating Fuel Filter.
3. Supply water to the seawater pickup pump as outlined in Flushing Cooling System.
4. Start the engine and check for fuel leaks. If leaks exist, stop the engine immediately.
Recheck filter installation.
5. Start the engine. Operate at idle rpm until it reaches normal operating temperature and
the fuel stabilizer has been circulated. Shut off the engine.
6. Change the engine oil and filter.
7. If boat has been operated in salty, polluted or mineral-laden waters, flush cooling system
as outlined in Flushing Cooling System.
8. Prepare fuel system for extended storage as follows:
a. Close the fuel shut-off valve, if equipped. If no fuel shut off valve is present, a suitable
method must be employed to STOP the flow of fuel from the fuel tank to the engine
before proceeding.
b. Remove flame arrestor assembly and start engine.
c. While operating engine at fast idle (1000-1500 rpm), fog internal surfaces of induc-
tion system and combustion chambers by squirting approximately 8 ounces (227
grams) of Quicksilver Storage Seal or SAE 20W engine oil into carburetor bores.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-21
d. Squirt the remaining 2 ounces (57 g) of Storage Seal (or oil) rapidly into carburetor,
just as the engine begins to stall, due to lack of fuel. Allow engine to stop.
e. Turn ignition key to OFF position.
f. Refer to Flushing Cooling System and appropriately remove water supply to the
seawater pickup pump.
9. Clean flame arrestor and crankcase ventilation hoses and reinstall.
10. Drain seawater section of cooling system as outlined in Draining Instructions.
11. Closed Cooling System Models: Test coolant to ensure that it will protect against
freezing to the lowest temperature expected during storage.
12. Lubricate all items outlined in “Lubrication.”
13. Service batteries. Refer to manufacturers instructions.
14. Clean outside of engine and repaint any areas required with Quicksilver Primer and
Spray Paint. After paint has dried, spray Quicksilver Corrosion and Rust Preventive
Type II or wipe down with Quicksilver Storage Seal or SAE 20W engine oil.
15. For drive unit layup information, refer to appropriate Sterndrive Manual.
CAUTION
Sterndrive unit should be stored in full “down” position. Universal Joint bellows
may develop a “set” if unit is stored in raised position and may fail when unit is
returned to service.
Draining Instructions
Single Point Drain System
Some models are equipped with a single point drain system consisting of 2 hoses with hard-
ware and a T-handle retrieval tool (shown below). This system drains the seawater section
of the engine only.
76242
a
b
a-T-handle Retrieval Tool
b-Hoses
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-22 90-861329--1 MARCH 1999
If your engine is equipped with this device, follow this procedure:
1. Detach the hoses from the top fittings.
76243
a
a-Fittings
2. Lower hoses into bilge. If hoses have developed a set, T-handle retrieval tool can be
used to push hoses below their connection point.
76244
a
b
a-Hoses
b-Connection Points
IMPORTANT: Hoses must be lowered below their connection point on the engine in
order to drain completely.
3. If hoses do not drain, use wire to remove blockage.
4. Pull hoses back into original position after draining is complete. Reconnect to fittings.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-23
Draining Seawater (Raw-Water) Cooled Models
NOTICE
Refer to Cold Weather or Extended Storage Precautions in this section,
BEFORE proceeding.
1. Engine must be as level as possible to ensure complete draining of cooling system.
2. Remove drain plugs from cylinder block and manifold.
71424
a
a-Drain Plug (Port and Starboard)
3. Repeatedly clean out drain holes using a stiff piece of wire. Do this until entire system
is drained.
NOTE: It may be necessary to lift, bend or lower hoses to allow water to drain completely
when hoses are disconnected.
4. Remove and lower the hoses to allow them to drain.
75815
b
a
a-Inlet Hose
b-Circulating Pump Hose
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-24 90-861329--1 MARCH 1999
5. Insert a small wire (repeatedly) to make sure that vent holes and water drain holes and
passages (as shown) are unobstructed and open.
71216
70134
d
a
c
f
b
e
c
f
a-Speedometer Pitot Tube
b-Gear Housing Cavity Drain Hole
c-Trim Tab Cavity Vent Hole
d-Trim Tab Cavity Drain Passage
e-Gear Housing Water Drain Hole (One Each - Port and Starboard)
f-Gear Housing Cavity Vent Hole
6. Crank engine over SLIGHTLY, with starter motor, to purge any water trapped in seawa-
ter pickup pump. DO NOT ALLOW ENGINE TO START.
CAUTION
If boat is in the water or is to remain in the water, seacock (if equipped) must remain
closed until engine is to be restarted, to prevent water from flowing back into
cooling system. If boat is not fitted with a seacock, seawater inlet hose must remain
disconnected and plugged, to prevent water from flowing into cooling system
and/or boat. As a precautionary measure, attach a tag to the ignition switch or
steering wheel with the warning that the seacock must be opened or the seawater
inlet hose reconnected prior to starting the engine.
7. After cooling system has been drained completely, coat threads of drain plugs with
Quicksilver Perfect Seal and reinstall. Tighten drain plugs securely. Reconnect hoses
and tighten all hose clamps securely. If NOT equipped with seacock: seawater inlet
hose must remain disconnected and plugged until engine is to be restarted.
IMPORTANT: MerCruiser recommends that propylene glycol antifreeze (nontoxic
and biodegradable, which makes it friendly to lakes and rivers) be used in seawater
section of the cooling system for cold weather or extended storage. Make sure that
the propylene glycol antifreeze contains a rust inhibitor and is recommended for use
in marine engines. Be certain to follow the propylene glycol manufacturers recom-
mendations.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-25
8. For additional assurance against freezing and rust, remove the thermostat cover and
thermostat. Fill the engine seawater cooling system with a mixture of antifreeze and tap
water mixed to manufacturers recommendation to protect engine to the lowest temper-
ature to which it will be exposed during cold weather or extended storage. Using a new
gasket, reinstall thermostat and cover. Tighten cover bolts to 30 lb-ft (41 Nm).
72589
a
b
c
d
e
f
g
76246
b
c
d
c
g
a-Lifting Eye
b-Cover
c-Gasket
d-Hose
e-Thermostat
f-Fitting
g-Housing
NOTE: Hoses shown removed only to indicate flow. Do not remove hoses.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-26 90-861329--1 MARCH 1999
Draining Seawater Section of Closed Cooled (Coolant) Models
NOTICE
Refer to Cold Weather or Extended Storage Precautions in this section,
BEFORE proceeding.
CAUTION
If boat is in the water or is to remain in the water, seacock (if equipped) must remain
closed until engine is to be restarted to prevent contaminated water from flowing
back into cooling system. If boat is not fitted with a seacock, water inlet hose must
be left disconnected and plugged to prevent contaminated water from flowing into
cooling system and/or boat. As a precautionary measure, attach a tag to the ignition
switch or steering wheel with the warning that the seacock must be opened or the
water inlet hose reconnected prior to starting the engine.
1. Ensure engine is as level as possible to ensure complete draining of cooling system.
2. Remove drain plug from the following locations:
a. Aft (rear) drain plug from the heat exchanger.
73581
a
a-Heat Exchanger Drain Plug
b. Bottom of exhaust manifold.
75177
a
a-Exhaust Manifold Drain Plug
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-27
3. Repeatedly clean out drain holes using a stiff piece of wire. Do this until entire system
is drained.
NOTE: It may be necessary to lift or bend hoses to allow water to drain completely.
4. Make sure gear housing water vent and drain holes, speedometer pitot hole and trim
tab cavity vent and drain holes are open and unobstructed.
71216
d
b
a
c
a-Vent Holes
b-Anode Cavity Drain Holes
c-Drain Hole
d-Speedometer Pitot Hole
5. Crank engine over,slightly with starter motor to purge any water trapped in seawater
pickup pump. Do not allow engine to start.
6. After cooling system has been drained completely, install drain plugs, reconnect hoses
and tighten all hose clamps securely.
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-28 90-861329--1 MARCH 1999
Recommissioning
NOTICE
Refer to Cold Weather or Extended Storage Precautions in this section
BEFORE proceeding.
WARNING
To prevent possible injury or damage to equipment, do not install battery until all
maintenance has been performed on engine.
1. Check that all cooling system hoses are connected properly and hose clamps are tight.
Check that all drain plugs are installed and tightened securely.
2. Inspect drive belts.
CAUTION
When installing battery, be sure to connect NEGATIVE () battery cable to
NEGATIVE () battery terminal and POSITIVE (+) battery cable to POSITIVE (+)
battery terminal. If battery cables are reversed, electrical system damage will result.
3. Install fully-charged battery. Clean battery cable clamps and terminals and reconnect
cables (see CAUTION listed above). Tighten each cable clamp securely when
connecting.
4. Coat terminal connections with a battery terminal anti-corrosion agent.
5. Perform all maintenance tasks listed in the MAINTENANCE SCHEDULES, except
those performed during the power package lay up procedure.
6. Perform all checks in the BEFORE STARTING column of the Operation and
Maintenance Manual OPERATION CHART.
CAUTION
Refer to FLUSHING COOLING SYSTEM before starting engine.
7. Supply water to the seawater pickup pump as outlined in Flushing Cooling System.
8. Start engine and closely observe instrumentation to make sure that all systems are
functioning correctly.
9. Carefully inspect engine for fuel, oil, fluid, water and exhaust leaks.
10. Check steering system and shift and throttle controls for proper operation.
11. For drive unit, refer to appropriate sterndrive manual.
Index
MAINTENANCE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1B-29
THIS PAGE IS INTENTIONALLY BLANK
Index
MAINTENANCE SERVICE MANUAL NUMBER 26
Page 1B-30 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
Index
1
C
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-1
IMPORTANT INFORMATION
Section 1C - Troubleshooting
Table of Contents
Precautions 1C-2. . . . . . . . . . . . . . . . . . . . . . . . . .
Used Spark Plug Analysis 1C-3. . . . . . . . . . . . . .
Spark Plug Analysis 1C-4. . . . . . . . . . . . . . . . . . .
Normal Condition 1C-4. . . . . . . . . . . . . . . . . . .
Chipped Insulator 1C-4. . . . . . . . . . . . . . . . . . .
Wet Fouling (Oil Deposits) 1C-4. . . . . . . . . . .
Cold Fouling 1C-5. . . . . . . . . . . . . . . . . . . . . . .
Overheating 1C-5. . . . . . . . . . . . . . . . . . . . . . .
High Speed Glazing 1C-5. . . . . . . . . . . . . . . . .
Scavenger Deposits 1C-6. . . . . . . . . . . . . . . .
Pre-Ignition Damage 1C-6. . . . . . . . . . . . . . . .
Reversed Coil Polarity 1C-6. . . . . . . . . . . . . . .
Splashed Deposits 1C-7. . . . . . . . . . . . . . . . . .
Mechanical Damage 1C-7. . . . . . . . . . . . . . . .
Poor Boat Performance and/or Poor
Maneuverability 1C-8. . . . . . . . . . . . . . . . . . . . . .
Improper Full Throttle Engine RPM 1C-9. . . . . .
RPM Too High 1C-9. . . . . . . . . . . . . . . . . . . . .
RPM Too Low 1C-9. . . . . . . . . . . . . . . . . . . . . .
Engine Cranks Over But Will Not Start
Or Is Hard To Start 1C-10. . . . . . . . . . . . . . . . . .
Important Information 1C-10. . . . . . . . . . . . . .
EST Ignition System Check 1C-11. . . . . . . . . . . .
Test Description 1C-11. . . . . . . . . . . . . . . . . . .
Ignition System Check 1C-12. . . . . . . . . . . . .
Engine Will Not Crank Over/Starter
Inoperative 1C-14. . . . . . . . . . . . . . . . . . . . . . . . .
Charging System Inoperative 1C-14. . . . . . . . . .
Noisy Alternator 1C-15. . . . . . . . . . . . . . . . . . . . . .
Fuel System Rich 1C-15. . . . . . . . . . . . . . . . . . . .
Fuel System Lean 1C-16. . . . . . . . . . . . . . . . . . . .
Carburetor Malfunction 1C-16. . . . . . . . . . . . . . . .
Engine Runs Poorly At Idle 1C-18. . . . . . . . . . . .
Engine Acceleration Is Poor 1C-19. . . . . . . . . . .
Engine Runs Poorly At High RPM 1C-19. . . . . .
Poor Fuel Economy 1C-20. . . . . . . . . . . . . . . . . .
Radio Noise 1C-21. . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting With Vacuum Gauge 1C-21. . .
Miscellaneous 1C-21. . . . . . . . . . . . . . . . . . . . . . .
Instrumentation Malfunction 1C-22. . . . . . . . . . .
Engine Noise 1C-22. . . . . . . . . . . . . . . . . . . . . . . .
Important Information 1C-22. . . . . . . . . . . . . .
Valve Cover Area 1C-23. . . . . . . . . . . . . . . . . .
Cylinder Area 1C-23. . . . . . . . . . . . . . . . . . . . .
Camshaft Area 1C-23. . . . . . . . . . . . . . . . . . . .
Crankshaft Area 1C-24. . . . . . . . . . . . . . . . . . .
Miscellaneous 1C-25. . . . . . . . . . . . . . . . . . . . .
Oil Pressure 1C-26. . . . . . . . . . . . . . . . . . . . . . . . .
Miscellaneous 1C-26. . . . . . . . . . . . . . . . . . . . .
Low Oil Pressure 1C-27. . . . . . . . . . . . . . . . . .
High Oil Pressure 1C-27. . . . . . . . . . . . . . . . . .
Excessive Oil Consumption 1C-28. . . . . . . . .
Water in Engine 1C-29. . . . . . . . . . . . . . . . . . . . . .
Important Information 1C-29. . . . . . . . . . . . . .
Water In Crankcase 1C-29. . . . . . . . . . . . . . . .
Water On Top Of Pistons 1C-30. . . . . . . . . . .
Engine Overheats 1C-31. . . . . . . . . . . . . . . . . . . .
Mechanical 1C-31. . . . . . . . . . . . . . . . . . . . . . .
Cooling System 1C-32. . . . . . . . . . . . . . . . . . .
Power Steering 1C-33. . . . . . . . . . . . . . . . . . . . . .
Poor, Erratic or No Assist 1C-33. . . . . . . . . . .
Noisy Pump 1C-34. . . . . . . . . . . . . . . . . . . . . . .
Fluid Leaks 1C-34. . . . . . . . . . . . . . . . . . . . . . .
Insufficient Water Flow From Alpha One
Sterndrive Unit Seawater Pickup Pump 1C-35
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-2 90-861329--1 MARCH 1999
Precautions
WARNING
Always disconnect battery cables from battery BEFORE working on fuel system to
prevent fire or explosion.
WARNING
Be careful when cleaning flame arrestor and crankcase ventilation hose; gasoline
is extremely flammable and highly explosive under certain conditions. Be sure that
ignition key is OFF. DO NOT smoke or allow sources of spark or open flame in area
when cleaning flame arrestor and crankcase ventilation hose.
WARNING
Be careful when changing fuel system components; gasoline is extremely flam-
mable and highly explosive under certain conditions. Be sure that ignition key is
OFF. DO NOT smoke or allow sources of spark or flame in the area while changing
fuel filter. Wipe up any spilled fuel immediately.
WARNING
Avoid gasoline fire or explosion. Improper installation of brass fittings or plugs into
fuel pump or fuel filter base can crack casting and/or cause a fuel leak. Follow
specific procedure, given in Section 5 of this manual, for all fuel line connections.
WARNING
Make sure no fuel leaks exist before closing engine hatch.
CAUTION
DO NOT operate engine without cooling water being supplied to water pickup holes
in gear housing, or water pump impeller will be damaged and subsequent
overheating damage may result.
CAUTION
DO NOT operate engine without water being supplied to seawater pickup pump on
engine, or pump impeller may be damaged and subsequent overheating damage to
engine may result. Engine may be operated with boat out of water, if instructions
under “Running Engine with Boat Out of Water,” following, are completed.
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-3
WARNING
When running engine with boat out of water, be certain that area in vicinity of
propeller is clear and that no person is standing nearby. As a precautionary
measure, it is recommended that the propeller be removed.
CAUTION
DO NOT run engine above 1500 rpm, as suction created by seawater pickup pump
may collapse water supply hose and cause engine to overheat.
WARNING
Be sure that engine compartment is well ventilated and that no gasoline vapors are
present to prevent the possibility of a FIRE or EXPLOSION.
WARNING
DO NOT leave helm unattended while performing idle speed adjustment.
Used Spark Plug Analysis
Use the following illustrations for determining serviceability of spark plug. Spark plug
condition also can suggest a variety of possible engine malfunctions and, therefore, can
indicate needed engine repairs. When old plugs are replaced, replace entire set. Perform
plug service only on those plugs suitable for additional service, using the following
procedures:
1. Remove any oil deposits with solvent and dry plugs thoroughly.
2. Open electrode gap wide enough to permit cleaning and filing.
3. Remove combustion deposits from firing end of spark plug with a plug cleaner. Blow off
with compressed air to remove abrasives.
4. File electrode surfaces to restore clean, sharp edges. Again remove filings with com-
pressed air.
5. Reset gap to specifications by bending only side electrode with proper tool.
IMPORTANT: When working on engine, spark plug holes and carburetor throat
should be kept covered to prevent foreign objects from entering combustion
chamber.
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-4 90-861329--1 MARCH 1999
Spark Plug Analysis
Normal Condition
Few deposits are present and probably will be light tan or gray in color. This plug shows that
plug heat range is compatible with engine, and engine is electrically and mechanically in
good running condition. With proper plug servicing (clean, file and re-gap), this plug can be
reinstalled with good results.
72420
Chipped Insulator
Chipped insulator usually results from careless plug re-gapping. Under certain conditions,
severe detonation also can split insulator firing ends. Plug must be replaced.
72420
Wet Fouling (Oil Deposits)
Plug becomes shorted by excessive oil entering combustion chamber, usually in engine with
many hours of operation. Worn piston rings, cylinder walls, valve guides or valve stem seals
are causes of oil entering combustion chamber. Only engine repairs will permanently relieve
oil wet fouling.
IMPORTANT: New engines or recently overhauled engines may wet foul plugs before
normal oil control is achieved with proper break-in procedures. Such fouled plugs
may be serviced (clean, file and re-gap) and reinstalled.
72420
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-5
Cold Fouling
Dry, black deposits indicate rich fuel mixture or weak ignition. Clogged flame arrestor,
flooding carburetor, sticky choke or weak ignition components all are probable causes. If,
however, only one or two plugs in set are fouled, check for sticking valves or bad ignition
leads. After correcting cause, service (clean, file and re-gap) plugs and reinstall.
72421
Overheating
Insulator is dull white or gray and appears blistered. Electrodes are eroded and there is an
absence of deposits. Check that correct plug heat range is being used. Also check for
over-advanced ignition timing, cooling system malfunction, lean fuel/air mixtures, leaking
intake manifold or sticking valves. Replace spark plugs.
72421
High Speed Glazing
Insulator has yellowish, varnish-like color, indicating that temperatures suddenly have risen,
usually during hard, fast acceleration under heavy load. Normal deposits do not get a
chance to blow off. Instead, they melt and form a conductive coating. Replace plugs. If
condition recurs, use colder heat range plug and service plugs more frequently.
72421
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-6 90-861329--1 MARCH 1999
Scavenger Deposits
Powdery white or yellow deposits are built up on shell, insulator and electrodes. This is
normal appearance with certain branded fuels. Accumulation on ground electrodes and
shell areas may be unusually heavy, but may be easily chipped off. Plugs can be serviced
(clean, file and re-gap) and reinstalled.
72422
Pre-Ignition Damage
Pre-ignition damage is caused by excessive high temperatures. Center electrode melts
first, followed by ground electrode. Normally, insulators are white but may be dirty if plug has
been misfiring. Check for correct plug heat range, advanced ignition timing, lean fuel
mixture, incorrect fuel used, malfunctioning cooling system, leaking intake manifold or lack
of lubrication.
72422
Reversed Coil Polarity
Concave erosion of ground electrode is an indication of reversed polarity. Center electrode
will show only normal wear. Engine will misfire and idle rough. To correct, reverse primary
coil leads. Replace spark plugs.
72422
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-7
Splashed Deposits
Spotted deposits, which sometimes occur after long delayed tune-up, accumulate after a
long period of misfiring. When normal combustion temperatures are restored, upon installa-
tion of new plugs, deposits loosen from top of piston and head and are thrown against hot
insulator. Clean and service plugs and reinstall.
72423
Mechanical Damage
Mechanical damage to spark plug firing end is caused by foreign object in combustion
chamber. Because of valve overlap, small objects can travel from one cylinder to another.
Check all cylinders, intake manifold and exhaust material to prevent further damage.
72423
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-8 90-861329--1 MARCH 1999
Poor Boat Performance and/or Poor Maneuverability
Symptom Cause
A. Improper drive unit trim angle
B. Improper weight distribution
C. Boat is underpowered
Bow too low
D. Permanent or power hook in boat
bottom
E. False bottom full of water
F. Improperly adjusted trim tabs (after
planes)
G. Dirty boat bottom (marine growth)
A. Improper drive unit trim angle
B. Propeller pitch too great
C. Dirty boat bottom (marine growth)
D. Poor running engine
Bow too high
E. Improper weight distribution
F. Rocker in boat bottom
G. False bottom full of water
H. Improperly adjusted trim tabs (after
planes)
A. Drive unit installed too high on transom
B. Dirty or rough boat bottom
C. Damaged propeller; pitch too small; di-
ameter too small
Propeller ventilating
D. Keel located too close to propeller or
too deep in the water
E. Water pickup or through hull fittings lo-
cated too close to propeller
F. Hook in boat bottom
G. Propeller plugged up with weeds
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-9
Improper Full Throttle Engine RPM
RPM Too High
Cause Special Information
Propeller
Damaged; pitch too low; diameter too
small; propeller hub slipping.
Boat
Water pickup or through hull fittings
mounted too close to propeller
(ventilation); keel located too close to
propeller and/or too deep in the water
(ventilation). Drive installed too high on
transom; wrong gear ratio.
Operation Unit trimmed out too far.
Engine coupler slipping
RPM Too Low
Cause Special Information
Propeller
Damaged; pitch too great; diameter too
great.
Boat
Dirty or damaged bottom; permanent or
power hook in bottom; false bottom full of
water. Drive installed too low on transom;
wrong gear ratio.
Operation Unit trimmed in too far.
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-10 90-861329--1 MARCH 1999
Engine Cranks Over But Will Not Start Or Is Hard To Start
Important Information
1. First, determine which engine system is causing the problem. To make an engine run,
basic components fuel, spark (ignition), and compression are required. If all three
components are present, the engine should run. If any one of the three are missing,
weak, or arriving at the wrong time the engine will not run.
2. Determine if there is fuel present by looking down the carburetor venturi while actuating
throttle. There should be a stream of fuel coming out of the accelerator pump nozzles
if the carburetor has fuel.
3. Check ignition system operation. Remove coil wire from tower on distributor cap. Hold
coil wire near ground and check for spark while cranking engine over. Repeat procedure
with spark plug wires. If there is spark at the spark plug wires, remove the spark plugs
and make sure they are correct type and heat range, and not fouled or burned.
4. Run a compression check on engine to make sure the engine is mechanically sound.
BRE
PN
BRE
BRE
+ C
+ C
PNK
PUR
GRY
BRN
WHT
WHT
WHT/GRN
(+) (“C”)
PUR GRY
A
B
A
B
71572
a
b
c
d
e
f
g
i
h
a-Ignition Coil Connector
b-Pick-Up Coil
c-Distributor 3 Terminal Connector
d-Distributor HEI Module
e-Filter
f-Ignition Coil
g-To Distributor Cap
h-Primary
i-Secondary
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-11
EST Ignition System Check
Test Description
Numbers below refer to circled numbers on the diagnostic chart.
1. Two wires are checked, to ensure that an open is not present in a spark plug wire.
a. If spark occurs with EST connector disconnected, pick-up coil output is too low for
EST operation.
2. A spark indicates the problem must be the distributor cap or rotor.
3. Normally, there should be battery voltage at the “C” and “+” terminals. Low voltage would
indicate an open or a high resistance circuit from the distributor to the coil or ignition
switch. If “C” terminal voltage was low, but “+” terminal voltage is 10 volts or more, circuit
from “C” terminal to ignition coil or ignition coil primary winding is open.
4. Checks for a shorted module or grounded circuit from the ignition coil to the module. The
distributor module should be turned “OFF,” so normal voltage should be about 12 volts.
If the module is turned “ON,” the voltage would be low, but above 1 volt. This could cause
the ignition coil to fail from excessive heat. With an open ignition coil primary winding,
a small amount of voltage will leak through the module from the “BAT” to the “TACH”
terminal.
5. Applying a voltage (1.5 to 8 volts) to module terminal “P” should turn the module “ON”
and the “tach” terminal voltage should drop to about 7-9 volts. This test will determine
whether the module or coil is faulty or if the pick-up coil is not generating the proper
signal to turn the module “ON.” This test can be performed by using a DC battery with
a rating of 1.5 to 8 volts. The use of the test light is mainly to allow the “P” terminal to
be probed more easily. Some digital multi-meters can also be used to trigger the module
by selecting ohms, usually the diode position. In this position the meter may have a
voltage across its terminals which can be used to trigger the module. The voltage in the
ohm’s position can be checked by using a second meter or by checking the
manufacturer’s specification of the tool being used.
6. This should turn “OFF” the module and cause a spark. If no spark occurs, the fault is
most likely in the ignition coil because most module problems would have been found
before this point in the procedure. A module tester could determine which is at fault.
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-12 90-861329--1 MARCH 1999
Ignition System Check(1 of 2)
SPARK
CHECK FUEL, SPARK PLUGS, ETC.
SEE TROUBLESHOOTING.
1
DISCONNECT 4 TERMINAL CONNECTOR
ON DISTRIBUTOR AND CHECK FOR
SPARK.
IF A TACHOMETER IS CONNECTED TO THE TACH TERMINAL, DISCONNECT IT
BEFORE PROCEEDING WITH THE TEST.
CHECK SPARK AT PLUG WIRE USING AN INDUCTIVE PICKUP TIMING LIGHT
WHILE CRANKING. A FLASHING LIGHT INDICATES SPARK. (IF NO SPARK ON FIRST
WIRE, CHECK SECOND WIRE.) A FEW SPARKS AND THEN NOTHING
IS CONSIDERED NO SPARK.
NO SPARK
CHECK FOR SPARK AT COIL WIRE WITH TIMING
LIGHT WHILE CRANKING. (LEAVE TIMING LIGHT
CONNECTED TO COIL WIRE FOR STEPS 3-6).
NO SPARK
DISCONNECT DISTRIBUTOR 2 TERMINAL C/+
CONNECTOR.
IGNITION SWITCH ON, ENGINE STOPPED.
CHECK VOLTS AT “+” AND “C” TERMINALS OF
DISTRIBUTOR HARNESS CONNECTION.
1A
2
3
RECONNECT DISTRIBUTOR 2
TERMINAL CONNECTOR.
WITH IGNITION ON, CHECK VOLTAGE
FROM TACH. TERMINAL TO GROUND
BOTH TERMINALS 10
VOLTS OR MORE
CHECK FOR OPEN OR
GROUND IN CKT. FROM
“C” TERMINAL TO IGNI-
TION COIL. IF CKT IS OK,
FAULT IS IGNITION COIL
OR CONNECTION.
UNDER 10 VOLTS
“C”TERMINAL ONLY
4
REPAIR OPEN
TACH. LEAD OR
CONNECTION AND
REPEAT TEST #4.
CONNECT TEST LIGHT FROM TACH.
TERMINAL TO GROUND.
CRANK ENGINE AND OBSERVE
LIGHT.
OVER 10 VOLTS
REPLACE MODULE AND
CHECK FOR SPARK
FROM COIL AS IN STEP 6.
UNDER 1 VOLT
1 TO 10 VOLTS
REPLACE
IGNITION
COIL.
NO
SPARK
SPARK
SYSTEM
OK
NO SPARK
SPARK
REPAIR WIRE FROM MOD-
ULE “+” TERMINAL TO “B”
TERMINAL OF BLACK
IGNITION COIL CONNEC-
TOR OR PRIMARY CKT. TO
IGNITION SWITCH.
BOTH TERMINALS
UNDER 10 VOLTS
CHART CONTINUED
ON NEXT PAGE
a
b
INSPECT CAP FOR WATER,
CRACKS, ETC. IF OK,
REPLACE ROTOR.
SPARK
REPLACE MAGNETIC
SHAFT ASSEMBLY.
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-13
Ignition System Check (2 of 2)
5
REPLACE IGNITION COIL AND
RECHECK FOR SPARK WITH
TIMING LIGHT. IF STILL NO
SPARK, REINSTALL ORIGINAL
COIL AND REPLACE
DISTRIBUTOR MODULE.
LIGHT ON
STEADY
LIGHT
BLINKS
NO DROP IN VOLTAGE
CHECK MODULE GROUND.
IF OK, REPLACE MODULE.
CHECK FOR SPARK FROM COIL WIRE
WITH TIMING LIGHT AS TEST LIGHT IS
REMOVED FROM MODULE TERMINAL
VOLTAGE DROPS
6
SPARK
REPLACE IGNITION COIL
AND REPEAT STEP 5.
NO SPARK
IS ROTATING POLE
PIECE STILL MAGNETIZED?
SYSTEM OKIGNITION COIL REMOVED IS OK,
REINSTALL COIL AND CHECK
COIL WIRE FROM DIST. CAP. IF
OK, REPLACE DISTRIBUTOR
MODULE.
REPLACE POLE
PIECE AND
SHAFT ASSEMBLY.
NO
YES
CHECK PICK-UP COIL OR
CONNECTIONS (COIL
RESISTANCE SHOULD BE
500-1500 OHMS AND
NOT GROUNDED.)
Fig. 1
TEST LIGHT
TO DC
POWER
SUPPLY
(1.5 to 8 V)
b
a
NO SPARK
SPARK
CHART CONTINUED
FROM PREVIOUS
PAGE
DISCONNECT DISTRIBUTOR 4 TERMINAL CONNECTOR.
REMOVE DISTRIBUTOR CAP.
DISCONNECT PICK-UP COIL CONNECTOR FROM MODULE.
CONNECT VOLTMETER FROM TACH. TERMINAL TO GROUND.
IGNITION ON.
INSULATE A TEST LIGHT PROBE TO 1/4, FROM TIP AND
NOTE VOLTAGE, AS TEST LIGHT IS MOMENTARILY CON-
NECTED FROM A VOLTAGE SOURCE (1.5 TO 8 V) TO MODULE
TERMINAL “P” (CHART 1 OF 2 PAGE 11).
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-14 90-861329--1 MARCH 1999
Engine Will Not Crank Over/Starter Inoperative
Cause Special Information
Remote control lever not in neutral
position
Battery charge low; damaged wiring; loose
electrical connections
Circuit breaker tripped
Blown fuse
Ignition switch
Slave solenoid
Faulty neutral start safety switch Open circuit
Starter solenoid
Starter motor
Mechanical engine malfunction
Charging System Inoperative
Cause Special Information
Loose or broken drive belt
Engine rpm too low on initial start Rev engine to 1500 rpm
Loose or corroded electrical connections
Faulty battery gauge Best way to test is to replace gauge
Battery will not accept charge Low electrolyte or failed battery
Faulty alternator or regulator
Refer to SECTION 4C for complete
Charging System diagnosis procedures
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-15
Noisy Alternator
Cause Special Information
Loose mounting bolts
Drive belt Worn, frayed or loose belt
Loose drive pulley
Worn or dirty bearings
Faulty diode trio or stator
Fuel System Rich
Cause Special Information
Warm engine carburetor percolation
Fuel boils out of float bowl when shut off
and warm. Floods intake manifold.
Clogged flame arrestor
Automatic choke not opening
Float adjustment
Float leaks or is saturated with fuel
Needle and seat leaking
Carburetor gaskets leaking
Excessive fuel pump pressure Unseats needle and seat
Cracked or porous carburetor body
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-16 90-861329--1 MARCH 1999
Fuel System Lean
Cause Special Information
Empty fuel tank
Fuel shut-off valve closed (if equipped)
Vapor lock Engine will not start after warm engine
shut down
Automatic choke Stuck open, wrong adjustment
Fuel tank vent plugged
Engine will start initially. After a short time
of running, engine will stall and will not
restart for a period of time. Can verify it is
a vent problem by running engine with
filler cap loose. Fill cap will act as a vent.
Air leak on suction side of fuel system
Sucks air into fuel system reducing fuel
volume
Plugged or pinched fuel line
Fuel pump Low pump pressure
Carburetor Malfunction
Symptoms Cause
A. Needle and seat
B. Float adjustment
C. Saturated float
Flooding
D. Gaskets leaking
E. Cracked fuel bowl
F. Fuel percolation
G. Automatic choke
A. Idle rpm too low
B. Idle mixture screws
C. Idle passages dirty
Rough idle
D. Throttle valves not closing
E. Engine flooding
F. Vacuum leak
G. Throttle body heat passages plugged
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-17
Carburetor Malfunction (continued)
A. Accelerator pump
B. Leaking gaskets
C. Automatic choke
D. Power piston or power valve
Hesitation or acceleration flatness
E. Throttle valves
F. Throttle body heat passages plugged
G. Main metering jets
H. Float adjustment
I. Secondary air valve wind-up
A. Main metering jets
B. Leaking gaskets
C. Float adjustment
Engine surges
D. Saturated float
E. Power piston or valve
F. Throttle valves
A. Power piston or valve
B. Float adjustment
Low top speed or lack of power
C. Main metering jets
D. Leaking gaskets
A. Idle rpm too low
B. Idle mixture screws
Poor cold engine operation
C. Throttle valves
D. Automatic choke
E. Engine flooding
A. Idle rpm too low
B. Idle mixture screws
C. Engine flooding
Engine stalls
D. Automatic choke
E. Dirt in carburetor
F. Accelerator pump
G. Leaking gaskets
Hard starting Refer to Engine Starts Hard
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-18 90-861329--1 MARCH 1999
Engine Runs Poorly At Idle
Cause Special Information
Clogged flame arrestor
Improper idle fuel mixture adjustment
Problem in ignition system causing the
engine to run rough
Idle mixture screw adjusted incorrectly
Engine floods at idle
Bad needle and seat
Engine floods at idle
Incorrect float level drop
If carburetor (2 barrel only) has a solid
needle, replace with a spring loaded
needle
Moisture on ignition components Cap or spark plug wires arcing
Water in fuel
Low grade or stale fuel
Incorrect ignition timing
Automatic choke
Spark plugs Fouled, burned, cracked porcelain
Spark plug wires Insulation breakdown, wires broken
Defective coil
Cracked or dirty distributor cap
Incorrect float level
Dirty carburetor
Vacuum leak Leak at manifold or carburetor base
Incorrect fuel pump pressure
Too low - cant supply the carburetor
Too high - unseats the needle and seat
Low compression Also check for blown head gasket
Loose or worn distributor Timing changes
Water leaking into cylinders
Head gasket, exhaust manifold, cracked
head or valve seat
Loose or broken engine mounts
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-19
Engine Acceleration Is Poor
Cause Special Information
Also refer to Poor Boat Performance
Idle mixture screws
Incorrect ignition timing
Incorrect distributor or amplifier advance
curve
Refer to SECTION 4B
Accelerator pump
Check for stream of raw fuel from
accelerator pump discharge nozzle, when
opening throttle with engine shut off
Cracked or dirty distributor cap or rotor
Vacuum leak Intake manifold or carburetor base
Spark plugs
Fouled, burned; wrong heat range;
cracked porcelain
Float adjustment
Dirty carburetor
Low compression
Engine Runs Poorly At High RPM
Cause Special Information
Also refer to Poor Boat Performance
Crankcase overfilled with oil
Check oil level with boat at rest in the
water.
Anti-siphon valve (if equipped) Restricting fuel supply
Plugged fuel tank vent
Fuel supply
Refer to Carburetor Malfunctions
(See “Table of Contents”)
Ignition timing
Low grade of fuel or water in the fuel
Spark plugs
Fouled, burned, cracked porcelain,
incorrect heat range
Spark plug wires Poor insulation, broken wires
Distributor cap or rotor Dirty or cracked
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-20 90-861329--1 MARCH 1999
Engine Runs Poorly At High RPM (continued)
Cause Special Information
Coil
Distributor Excessive play in shaft
Engine overheating Refer to Engine Overheats
Low compression Worn valves, rings, cylinders, etc.
Restricted exhaust
Poor Fuel Economy
Cause Special Information
Fuel leaks
Operator habits
Prolonged idling; slow acceleration; failure
to cut back on throttle once boat is on
plane; boat overloaded; uneven weight
distribution
Engine laboring
Bent, damaged or wrong propeller. Water
test boat for proper operating rpm at wide
open throttle
Clogged flame arrestor
Engine compartment sealed too tight Not enough air for engine to run properly
Boat bottom Dirty (marine growth), hook, rocker
Carburetor
Idle mixture settings, accelerator pump
adjustments, linkage binding, choke
adjustment, carburetor flooding over, main
fuel jets
Improper fuel
Crankcase ventilation system not working
Engine needs tune-up
Engine running too cold or too hot
Plugged or restricted exhaust
Engine Low compression
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-21
Radio Noise
Cause Special Information
A popping noise that will increase with
engine rpm. Noise will stop as soon as
engine is turned off.
Ignition System - wrong spark plugs;
cracked distributor cap; cracked coil tower;
leaking spark plug wires; moisture on
ignition components
High pitched whine in the radio
Alternator - poor brush contact on the slip
rings
A hissing or crackling noise when
instruments are jarred with ignition on
Instrumentation - loose connections or
antennae wire routed too close to
instruments
Varying unexplained noises
Accessories - bilge pump, bilge blower;
fish finder; depth locator; cabin heater
motor, etc. Disconnect one at a time until
noise disappears.
Troubleshooting With Vacuum Gauge
Reading Cause
Steady reading between 15-21 inches at
idle rpm
Normal
Extremely low reading, but steady at idle
rpm
Vacuum leak; incorrect timing;
underpowered boat; faulty boat bottom
Fluctuates between high and low at idle
rpm
Blown head gasket between two adjacent
cylinders
Fluctuates 4 or 5 inches very slowly at idle
rpm
Carburetor needs adjustment; spark plug
gap too narrow; valves are sticking
Fluctuates rapidly at idle, steadies as rpm
is increased
Valve guides are worn
Continuously fluctuates between low and
normal reading at regular intervals at idle
rpm
Burned or leaking valve
Miscellaneous
Cause Special Information
Low grade or stale fuel
Water in fuel
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-22 90-861329--1 MARCH 1999
Instrumentation Malfunction
Cause Special Information
Faulty wiring, loose or corroded terminals
Faulty key switch Test, as outlined in SECTION 4D
Faulty gauge Test, as outlined in SECTION 4D
Faulty sender Test, As outlined in SECTION 4D
Engine Noise
Important Information
No definite rule or test will positively determine source of engine noise. Use the following
information only as a general guide to engine noise diagnosis.
1. Use a timing light to determine if noise is timed with engine speed or one-half engine
speed. Noises timed with engine speed are related to crankshaft, rods, pistons, piston
pins and flywheel. Noises timed to one-half engine speed are valve train related.
2. The use of a stethoscope can aid in locating a noise source. Because noise will travel
to other metal parts not involved in the problem, caution must be exercised.
3. If you believe noise is confined to one particular cylinder, ground spark plug leads one
at a time. If noise lessens noticeably or disappears, it is isolated to that particular cylin-
der.
4. Try to isolate the noise to location in engine: front to back, top to bottom. This can help
determine what components are at fault.
5. Sometimes noises can be caused by moving parts coming in contact with other compo-
nents. Examples are: flywheel or coupler; exhaust flappers rattling against exhaust pipe;
crankshaft striking (pan, pan baffle, or dipstick tube); rocker arm striking valve cover;
and loose flywheel cover. In many cases if this is found to be the problem, a complete
engine teardown is not necessary.
6. When noise is isolated to a certain area and component, removal and inspection will be
required. Refer to proper sections of service manual for information required for service.
7. If noise cannot be distinguished between engine and drive unit, remove drive from boat.
Run a water supply directly to engine. Run engine without the drive to determine if noise
is still there.
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-23
Valve Cover Area
Location Possible Causes
A. Rocker arm striking valve cover
Valve cover area, timed to one-half engine
B. Rocker arm out of adjustment
speed, noise could be confined to one
C. Worn rocker arm
cylinder or may be found in any multitude
of cylinders
D. Bent push rod
E. Collapsed filter
Cylinder Area
Location Possible Causes
A. Sticking valve
B. Carbon build-up
C. Connecting rod installed wrong
Cylinder area, may be confined to one
D. Bent connecting rod
cylinder or found in more than one
cylinder, timed to engine speed
E. Piston
cylinder, timed to engine speed
F. Piston rings
G. Piston pin
H. Cylinder worn
Camshaft Area
Location Possible Causes
A. Crankshaft timing sprocket
B. Timing chain
Camshaft area, front of engine,
C. Fuel Pump
timed to one half engine speed
D. Valve Lifter
E. Cam Bearings
A. Fuel Pump
Camshaft area, center of
engine, timed to one half
B. Valve Lifter
engine speed
C. Cam bearing
A. Distributor gear
Camshaft area, rear of engine,
B. Valve lifter
timed to one half engine speed
C. Cam bearings
A. Loss of oil pressure
Camshaft area, throughout
engine, timed to one half
B. Valve lifters
engine speed
C. Cam bearings
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-24 90-861329--1 MARCH 1999
Crankshaft Area
Location Possible Causes
A. Crankshaft timing sprocket
Crankshaft area, front of engine, timed to
B. Timing chain
Crankshaft area, front of engine, timed to
engine speed
C. Main bearing
D. Rod bearing
A. Crankshaft striking pan or pan baffle
Crankshaft area, center of engine, timed
B. Main bearing
to engine speed
C. Rod bearing
A. Loose flywheel cover
B. Loose coupler
Crankshaft area, rear of engine, timed to
C. Loose flywheel
engine speed
D. Main bearing
E. Rod bearing
A. Loss of oil pressure
Crankshaft area, throughout engine, timed
B. Main bearings
to engine speed
C. Rod bearings
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-25
Miscellaneous
Location / Noise Possible Causes
A. Advanced timing
B. Low octane fuel
Engine spark knock
C. Engine running hot
D. Carbon deposits in engine
A. Wrong ignition timing
B. Carburetor set too lean
C. Faulty accelerator pump
Popping through carburetor
D. Vacuum leak
E. Valve adjustment
F. Valve timing
G. Burned or stuck valve
A. Vacuum leak
B. Leaking exhaust (manifolds or pipes)
Hissing
C. Loose cylinder heads
D. Blown head gasket
A. Vacuum leak
Whistle
B. Dry or tight bearing in an accessory
A. Leaking high tension lead
Sparks jumping
B. Cracked coil tower
C. Cracked distributor cap
A. Drive belt slipping
Squeaks or squeals
B. Dry or tight bearing in an accessory
C. Parts rubbing together
Rattling in exhaust pipe area A. Exhaust shutters
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-26 90-861329--1 MARCH 1999
Oil Pressure
Miscellaneous
Problem Special Information
Measuring oil pressure
Use a good automotive oil pressure test
gauge. Do not rely on the oil pressure
gauge in the boat.
Check engine oil level with boat at rest in
the water
Oil level should be between the ADD and
FULL marks
Oil level in crankcase above FULL mark
May cause loss of engine rpm, oil
pressure gauge fluctuation, drop in oil
pressure, and hydraulic valve lifter noise
at high rpm
Oil level in crankcase below ADD mark
Low oil pressure; oil pressure gauge
fluctuation; internal engine noise and/or
damage
Change in oil pressure
This may be a normal condition. Oil
pressure may read high in the cooler times
of the day, and when engine is not up to
operating temperature. As the air
temperature warms up and engine is
running at normal opening temperature, it
is normal for oil pressure to drop.
Low engine oil pressure at idle
With modern engines and engine oils, low
oil pressure readings at idle do not
necessarily mean there is a problem. If
valve lifters do not “clatter” (at idle), there
is a sufficient volume of oil to lubricate all
internal moving parts properly. The reason
for the drop in oil pressure is that engine
heat causes an expansion of the internal
tolerances in the engine and, also, the oil
will thin out somewhat from heat.
Low engine oil pressure at idle after
running at a high rpm
Refer to preceding items
Boats with dual engines
It is not uncommon to see different oil
pressure readings between the two
engines, as long as both engines fall
within specifications. Differences in oil
pressure can be attributed to differences
in engine tolerances, gauges, wiring,
senders, etc.
Boats with dual stations Refer to preceding
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-27
Low Oil Pressure
Cause Special Information
Low oil level in crankcase
Defective oil pressure gauge and/or
sender
Verify with an automotive test gauge.
Refer to SECTION 4D for instrument
testing.
Thin or diluted oil
Oil broken down; contains water or gas;
wrong viscosity; engine running too hot or
too cold; excessive idling in cold water
(condensation)
Oil pump
Relief valve stuck open; pickup tube
restricted; worn parts in oil pump; air leak
on suction side of oil pump or pickup oil
tube
Oil leak can be internal or external
Oil passage plugs leaking, cracked or
porous cylinder block
Excessive bearing clearance
Cam bearings, main bearings, rod
bearings
High Oil Pressure
Cause Special Information
Oil too thick Wrong viscosity, oil full of sludge or tar
Defective oil pressure gauge and/or
sender
Verify with an automotive test gauge
Clogged or restricted oil passage
Oil pump relief valve stuck closed
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-28 90-861329--1 MARCH 1999
Excessive Oil Consumption
NOTE: Normal consumption is one quart of oil consumed in 5-15 hours of operation at wide-
open-throttle (especially in a new or rebuilt engine).
Cause
Special Information
Oil leaks
Clean bilge, run engine with clean white
paper on bilge floor, locate oil leak(s)
Oil too thin Oil diluted or wrong viscosity
Oil level too high
Drain holes in cylinder head plugged Oil will flood valve guides
Defective valve seals
Intake manifold gasket leaking
Worn valve stems or valve guides
Defective oil cooler (if so equipped) Crack in cooler tubes
Defective piston rings
Glazed, scuffed, worn, stuck, improperly
installed; ring grooves worn; improper
break-in; wrong end gap
Defective cylinders
Out of round, scored, tapered, glazed;
excessive piston to cylinder clearance;
cracked piston
Excessive bearing clearance
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-29
Water in Engine
Important Information
IMPORTANT: First determine location of water in engine. This information can be of
great help when trying to determine where the water came from and how it got into
the engine. The three most common problems are water on top of pistons, water in
crankcase oil or water in crankcase oil and on top of pistons.
The first step, after locating water, is to remove all the water from the engine by removing
all spark plugs and pumping cylinders out by cranking engine over. Next change oil and filter.
Now, start engine and see if problem can be duplicated. If problem can be duplicated, there
is probably a mechanical problem. If the problem cannot be duplicated, the problem is either
an operator error or a problem that exists only under certain environmental conditions.
If water is contained to cylinder(s) only, it is usually entering through the intake system,
exhaust system or head gasket.
If the water is contained to crankcase only, it is usually caused by a cracked or porous block,
a flooded bilge or condensation.
If the water is located in both the cylinder(s) and the crankcase, it is usually caused by water
in the cylinders getting past the rings and valves or complete submersion.
Check for rust in the intake manifold or exhaust manifolds. Rust in these areas will show that
if the water entered these areas.
If water is contained to cylinder(s) only, it is usually entering through the intake system,
exhaust system or head gasket.
Water In Crankcase
Cause Special Information
Water in boat bilge
Boat has been submerged or bilge water
was high enough to run in through dipstick
tube
Water seeping past piston rings or valves
Refer to Water in Engine (On Top of
Pistons”)
Engine running cold
Defective thermostat, missing thermostat;
prolonged idling in cold water
Intake manifold leaking near a water
passage
Cracked or porous casting
Check cylinder head, cylinder block, and
intake manifold
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-30 90-861329--1 MARCH 1999
Water On Top Of Pistons
Cause Special Information
Operator shut engine off at high rpm
Engine “diesels” or tries to run backwards
Engine out of tune, poor fuel, high idle
rpm, timing set too high
Rain water running into flame arrestor Hatch cover
Spark plug misfiring
Improper combustion causes moisture in
the air to accumulate in the cylinder
Backwash through the exhaust system
Improper engine or exhaust hose
installation
Cracked exhaust manifold
Improper manifold to elbow gasket
installation
Loose cylinder head bolts
Blown cylinder head gasket
Check for warped cylinder head or
cylinder block
Cracked valve seat
Porous or cracked casting
Check cylinder heads, cylinder block, and
intake manifold
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-31
Engine Overheats
Mechanical
Cause Special Information
Engine rpm below specifications at
wide-open-throttle (engine laboring)
Damaged or wrong propeller; growth on
boat bottom; false bottom full of water
Wrong ignition timing Timing too far advanced or retarded
Sticking distributor advance weights
Spark plug wires crossed (wrong firing
order)
Lean fuel mixture
Refer to Carburetor Malfunction in this
section
Wrong heat range spark plugs
Exhaust restriction
Valve timing off
Jumped or improperly installed timing
chain
Blown head gasket(s)
A blown head gasket(s) normally cannot
be detected by a compression check.
Normally the engine will run at normal
temperature at low rpm, but will overheat
at speeds above 3000 rpm.
Engines that are seawater cooled:
Using a clear plastic hose, look for air
bubbles between seawater pump and
engine. If there are no bubbles present,
install clear plastic hose between
thermostat housing and manifold(s). If air
bubbles are present at a higher rpm, it is a
good indication there is a blown head
gasket.
Insufficient lubrication to moving parts of
engine
Defective oil pump, plugged oil passage,
low oil level
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-32 90-861329--1 MARCH 1999
Cooling System
Cause Special Information
IMPORTANT: The first step is to verify if
the engine is actually overheating or the
temperature gauge or sender is faulty
IMPORTANT: Best way to test gauge or
sender is to replace them.
Loose or broken drive belt
Seawater shutoff valve partially or fully
closed (if equipped)
Clogged or improperly installed sea
strainer
Loose hose connections between
seawater pickup and seawater pump inlet
(models with belt driven seawater pump
only)
Pump will suck air. Pump may fail to prime
or will force air bubbles into cooling
system.
Seawater inlet hose kinked or collapsed
Seawater pickup clogged
Obstruction on boat bottom causing water
turbulence
Obstruction will be in front of seawater
pickup, causing air bubbles to be forced
into cooling system
Defective thermostat
Exhaust elbow water outlet holes plugged
Insufficient seawater pump operation Worn pump impeller
Obstruction in cooling system such as
casting flash, sand, rust, salt, etc.
Refer to water flow diagram for engine
type being serviced
Engine circulating pump defective
Also refer to Engine Overheats
(Mechanical)”
IMPORTANT: In addition to previous
checks, make the following checks if
engine is equipped with closed
cooling.
Low coolant level
Antifreeze not mixed properly
Antifreeze should be mixed 50/50 or
maximum 60/40 (60% antifreeze, 40%
water)
Heat exchanger cores plugged
Water hoses reversed at the water
distribution block
Refer to water flow diagram in SECTION 6
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-33
Power Steering
Poor, Erratic or No Assist
Cause Special Information
Drive belt Worn, broken or out of adjustment
Low fluid level
Air in system
Air leak in lines or pump, or air from
installation. Refer to SECTION 8A for
bleeding procedure.
Leaking hoses
Refer to SECTION 8A for bleeding
procedure.
Steering cables and/or steering helm
Cable or helm partially frozen from rust or
corrosion; cable over-lubricated; improper
cable installation
Binding in sterndrive unit
Refer to appropriate Sterndrive Service
Manual
Restriction in hydraulic hoses Causes loss of pressure
Control valve not positioned properly, not
balanced properly, or the mounting nut is
loose
Mounting bracket adjusting screw loose or
mounting tube is loose
Faulty pump Flow control valve may be sticking
Worn piston ring or scored housing bore in
cylinder
Causes loss of pressure
Leaking valve body or loose fitting spool
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-34 90-861329--1 MARCH 1999
Noisy Pump
Cause Special Information
Drive belt Check belt tension
Low fluid level
Air in fluid
Air leak in lines, pump, or air form
installation
Faulty pump
Use stethoscope to listen for noise in
pump
Restricted fluid passages
Kinks or debris in hoses or debris in
passages
Stop nut adjusted improperly
Refer to appropriate Sterndrive Service
Manual
Steering cables installed that do not meet
BIA standards
Refer to appropriate Sterndrive Service
Manual
Fluid Leaks
Cause Special Information
Loose hose connections
Refer to SECTION 8A for bleeding instruc-
tions
Damaged hose
Oil leaking from top of pump
System overfilled; fluid contains water;
fluid contains air
Cylinder piston rod seal
Faulty seals in valve
Faulty seals in O-rings in pump
Cracked or porous metal parts
TROUBLESHOOTING
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 1C-35
Insufficient Water Flow From Alpha One Sterndrive Unit
Seawater Pickup Pump
Cause Special Information
Seawater shutoff valve partially or fully
closed (if equipped)
Water pickup clogged with foreign material
Kinked or broken bell housing to gimbal
housing water tube hose
Corroded through gimbal housing water
tube
Water pickup inserts warped. (Engine will
overheat while boat is underway.)
Water pickup must not protrude above
gear housing surface or inserts will create
an irregular or turbulent water flow over
the water pickup holes. Consequently, this
may cause loss of cooling water and
subsequent engine overheating. This
condition can be identified by cavitation
burn (pitting or erosion) on the gear
housing in the area aft of the water pick
up.
Damaged gear housing or accessories
improperly installed on boat bottom or
transom (speedometer pick up, depth
sounder transducer, etc.) Substantial
amount of barnacles or other marine
growth on gear housing or boat bottom.
(Engine will overheat while underway only)
An object or an irregularity on boat or gear
housing in area close to to water pickups
could create turbulence in water flow
going to water pickups. This could aerate
the water flow and cause engine to
overheat
Sterndrive installed too high on transom or
drive unit trimmed out too far out allowing
air to be drawn into pump. (Engine will
overheat while underway only)
Contact boat company if sterndrive is too
high. Instruct operator on proper trimming
technique if unit is trimmed out too far.
Bell housing-to-driveshaft housing O-ring
missing or damaged
Faulty seawater pickup pump
Seawater pickup tube corroded through
Driveshaft housing water pocket cover
cracked
Broken impeller blade or other obstruction
in water passages (usually lodges in drive-
shaft housing water pocket cover or cross
drilled water passage).
To check cross drilled water passages in
driveshaft housing, remove plug and pipe
plug located under decal on starboard side
of housing. Drive unit must be shifted into
reverse to remove pipe plug.
Water passage in driveshaft housing
improperly drilled
TROUBLESHOOTING SERVICE MANUAL NUMBER 26
Page 1C-36 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
2
A
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-1
REMOVAL AND INSTALLATION
Section 2A - MCM 3.0L (181 cid) - Alpha Drive
Table of Contents
Torque Specifications 2A-2. . . . . . . . . . . . . . . . . .
Lubricants/Sealers/Adhesives 2A-2. . . . . . . . . . .
Tools 2A-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 2A-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Removal 2A-3. . . . . . . . . . . . . . . . . . . .
Installation 2A-8. . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Installation 2A-8. . . . . . . . . . . . . . . . . .
Engine Alignment 2A-11. . . . . . . . . . . . . . . . . .
Engine Connections 2A-13. . . . . . . . . . . . . . .
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-2 90-861329--1 MARCH 1999
Torque Specifications
DESCRIPTION lb-in. lb-ft Nm
Power Steering Hydraulic Hose Fittings 23 31
Front Engine Mounts 35 47
Rear Engine Mounts 38 52
Drive Unit Shift Cables (Cable End and
Cable End Guide)
Tighten Until Contacts, Then Loosen 1/2
Turn. Spread Cotter Keys
Remote Control Shift Cables
Remote Control Throttle Cables
Hose Clamps
Tighten Securely
Battery Cables
Lubricants/Sealers/Adhesives
Description Part Number
Quicksilver Engine Coupler Spline Grease 92-816391A4
Quicksilver 2-4-C Marine Lubricant With Teflon 92-825407A3
Quicksilver Liquid Neoprene 92-25711--3
Loctite Pipe Sealant with Teflon Obtain Locally
Tools
Description Part Number
Engine Alignment Tool 91-805475A1
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-3
Removal
IMPORTANT: Sterndrive unit must be removed prior to engine removal. Refer to
Sterndrive Service Manual.
Engine Removal
1. Disconnect battery cables from battery.
22052
a
b
c
a-Negative (-) Battery Cable
b-Positive (+) Battery Cable
c-Rubber Boot (Slid Back From Terminal)
2. Remove instrument harness connector plug from engine harness receptacle after loos-
ening clamp.
WARNING
Be careful when working on fuel system. Gasoline is extremely flammable and
highly explosive under certain conditions. Do not smoke or allow spark or open
flame in area. Wipe up any spilled fuel immediately.
3. Disconnect and plug fuel line to prevent fuel in tank from leaking into bilge.
50738
b
a
a-Fuel Pump
b-Disconnect Fuel Inlet Line Here
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-4 90-861329--1 MARCH 1999
4. Disconnect throttle cable from carburetor and retain locknuts and hardware.
75810
a
b
c
d
e
a-Cable End Guide
b-Throttle Cable Anchor Screw
c-Cable Barrel
d-Elastic Stop Nut And Flat Washer
e-Throttle Lever
5. Disconnect shift cables and shift assist assembly (if equipped).
75811
e
a
b
c
d
a-Locking Nut
b-Shift Cable End
c-Cotter Pin
d-Shift Assist Assembly
e-Clevis Pin (w/Cotter Pin)
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-5
6. Disconnect and cap power steering hoses. Plug control valve hose connection holes.
75812
b
a
a-Power Steering Hoses
b-Control Valve
7. Loosen clamp and unplug wiring harness.
50626
a
b
c
a-Engine Wiring Harness Receptacle (Bracket)
b-Instrumentation Wiring Harness
c-Hose Clamp
8. Disconnect bullet connectors of trim sender wires (coming from transom assembly) from
engine harness.
NOTE: After wires are disconnected, remove them from clamps or Sta-Straps retaining
them to engine or hoses.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-6 90-861329--1 MARCH 1999
9. Disconnect engine harness wires from shift cut-out switch harness.
75499
a
a-Shift Cutout Switch Wires
10. Disconnect MerCathode wires from MerCathode controller if equipped.
11. Disconnect seawater inlet hose from gimbal housing.
72614
b
a
c
a-Water Tube
b-Hose Clamp (Tighten Securely)
c-Water Hose
12. Loosen hose clamps and disconnect exhaust elbow hose.
13. Remove both shift cables from shift plate. Retain locknuts and hardware.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-7
14. Disconnect any grounding wires and accessories that are connected to engine.
50636
a
a-Ground Stud
15. Disconnect (and suitably plug) fluid hoses from power steering control valve on transom.
CAUTION
Center lifting eye (located on top of thermostat housing) is used for engine align-
ment only. DO NOT use to lift entire engine.
CAUTION
DO NOT allow lifting sling to hook or compress engine components or damage will
occur.
16. Support engine with suitable sling through lifting eyes on engine and remove front and
rear engine mounting bolts. Retain hardware.
75815
a
b
b
Typical
a-Center Lifting (Aligning) Eye
b-Lifting Eye
17. Carefully remove engine. DO NOT hit power steering control valve.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-8 90-861329--1 MARCH 1999
Installation
Engine Installation
1. Be certain fiber washers (cemented in place) on inner transom plate are present. Inspect
fiber washers. Replace if worn or damaged.
2. Install double wound lockwashers onto inner transom plate inside fiber washer.
72023
a
d
c
b
a-Double Wound Lockwasher
b-Fiber Washer
c-Inner Transom Plate Mount
d-Locknut
3. Be certain rear engine mount locknuts are in position as shown.
4. Lubricate exhaust bellows with soap and water to ease installation.
5. Lubricate engine coupling splines with Quicksilver Engine Coupler Spline Grease.
72017
b
a
a-Lubricate Splines With Quicksilver Engine Coupler Grease 92-816391A4
b-Grease Fitting
CAUTION
Center lifting eye (located on top of thermostat housing) is used for engine align-
ment only. DO NOT use to lift entire engine.
CAUTION
DO NOT allow lifting sling to hook or compress engine components or damage will
occur.
6. Attach a suitable sling to lifting eyes on engine and adjust so that engine is level when
suspended.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-9
7. Lift engine into position (in boat), using an overhead hoist.
75815
a
b
b
a-Center Lifting (Aligning) Eye
b-Lifting Eye
8. Align rear engine mounts with inner transom plate mounts while simultaneously aligning
exhaust tubes with exhaust pipe hoses (bellows). Do not fasten attaching hardware until
you have aligned engine.
75819
b
c
a
a-Bellows
b-Clamps
c-Exhaust Pipe
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-10 90-861329--1 MARCH 1999
IMPORTANT: Engine attaching hardware must be installed in sequence shown.
9. Install both rear engine mounting bolts and hardware as shown.
10. Torque mounting bolts to 38 lb-ft (52 Nm).
72535
a
b
c
d
e
f
g
h
a-Rear Engine Mounting Bolt
b-Large Steel Washer
c-Metal Spacer
d-Rear Engine Mount
e-Double Wound Lockwasher
f-Fiber Washer
g-Inner Transom Plate Mounts
h-Locknut (Hidden In This View)
CAUTION
When lowering engine into position DO NOT set engine on shift cable. Shift cable
outer casing can be crushed causing difficult or improper shifting.
11. Set engine down on stringers and relieve hoist tension. Disconnect sling from engine
lifting eyes and switch sling to center lifting eye.
75815
a
b
b
a-Center Lifting (Aligning) Eye
b-Lifting Eyes (rear lifting eye hidden in this view)
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-11
Engine Alignment
IMPORTANT: The modified 91-57797A3 tool or the new tool 91-805475A1 will align all
current Alpha One as well as all older engines that used the older 91-57797A3.
CAUTION
To avoid damage to gimbal bearing, engine coupler, or alignment tool:
w DO NOT attempt to force alignment tool!
w DO NOT raise or lower engine with alignment tool inserted (or partially inserted)
in gimbal bearing or engine coupler.
1. Attempt to insert solid end of Quicksilver Alignment Tool through gimbal bearing and into
engine coupler splines.
2. If Quicksilver Alignment Tool will not insert easily, while observing the above precau-
tions, CAREFULLY raise and lower front of engine with hoist. Continue as needed until
tool will SLIDE FREELY all the way in and out of engine coupler splines.
70013
a
b
a-Alignment Tool (91-805475A1)
b-Aligning End
72585
a
b
c
a-Alignment Tool
b-Gimbal Bearing
c-Engine Coupler
IMPORTANT: Turn both front engine mount adjustment nuts an equal amount in
direction required to align engine.
3. Adjust front engine mounts until they rest on boat stringers.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-12 90-861329--1 MARCH 1999
4. Relieve hoist tension entirely and fasten both front mounts to boat stringer using appro-
priate hardware (lag bolts or through-bolts, etc).
5. Recheck alignment with alignment tool. Tool must enter coupler splines freely. If not,
readjust front mounts.
6. When alignment is correct, tighten locknut or nut with lockwasher on each mount
securely.
22054
a
b
c
d
e
b
a-Front Mount
b-Attaching Bolts And Flat Washers
c-Adjustment Nut
d-Locknut
e-Jam Nut
7. Remove alignment tool if not already removed.
8. Tighten all exhaust system clamps securely as shown (use two clamps on each
connection).
50633
a
a-Hose Clamps
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-13
Engine Connections
IMPORTANT: When routing all wire harnesses and hoses, be sure they are routed and
secured to avoid coming in contact with hot spots on engine and avoid contact with
moving parts.
1. Connect seawater inlet hose to water tube at gimbal housing with hose clamp. Tighten
clamp securely.
72614
b
a
c
a-Water Inlet Tube
b-Hose Clamp
c-Seawater Inlet Hose
2. Connect instrument harness to engine harness with clamp. Tighten clamp securely.
50626
a
b
c
a-Engine Wiring Harness
b-Instrument Harness
c-Clamp
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-14 90-861329--1 MARCH 1999
3. Connect trim position sender leads from gimbal housing to leads from engine harness.
72992
a
b
c
d
a-BROWN/WHITE - From Engine Harness
b-BLACK - From Engine Harness
c-BLACK - From Transom Assembly
d-BLACK - From Transom Assembly
WARNING
Be careful when working on fuel system. Gasoline is extremely flammable and
highly explosive under certain conditions. Do not smoke or allow spark or open
flame in area. Wipe up any spilled fuel immediately.
4. Connect fuel line from fuel tank(s) to engine. Make certain connections are secure.
Check for leaks.
50738
b
a
a-Fuel Pump
b-Connect Flexible Fuel Inlet Line Here
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-15
5. Connect throttle cable using hardware retained and adjust as follows:
a. Place remote control handle(s) in NEUTRAL, idle position.
IMPORTANT: Be sure that cable is routed in such a way as to avoid sharp bends and/
or contact with moving parts. DO NOT fasten any items to throttle cable. Outer cable
must be free to move when cable is actuated.
75817
b
a
a-Anchor Bolt
b. Install cable end guide on throttle lever, then push cable barrel lightly toward throttle
lever end. (This will place a slight preload on cable to avoid slack in cable when
moving remote control lever.) Adjust barrel on throttle cable to align with anchor stud.
c. Secure throttle cable with hardware (retained) as shown. Tighten cable end guide
locknut until it contacts and then loosen one full turn. Tighten throttle cable anchor
screw securely. DO NOT OVERTIGHTEN, as cable must pivot freely.
75810
a
b
c
d
e
a-Cable End Guide
b-Throttle Cable Anchor Screw
c-Cable Barrel
d-Cable End Guide Locknut
e-Throttle Lever
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-16 90-861329--1 MARCH 1999
d. Place remote control throttle lever in the wide-open-throttle (W.O.T.) position.
Ensure that throttle shutters (valves) are completely open and throttle shaft lever
contacts carburetor body casting.
e. Return remote control throttle lever to idle position and ensure that throttle lever con-
tacts idle speed adjustment screw.
72283
b
c
a
e
d
a-Throttle Lever Tang
b-Carburetor Body
c-Idle Speed Adjustment Screw
d-Wide Open Throttle
e-Idle
50633
b
a
a-Throttle Lever
b-Idle Speed Adjustment Screw
IMPORTANT: Do not attach any accessory ground (–) wires to transom plate ground
point. Accessory ground wires should only be attached to ground stud on engine.
6. Connect any grounding wires or accessories that have been disconnected.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-17
7. Connect MerCathode wires to MerCathode controller assembly as shown, if equipped.
Apply a thin coat of Quicksilver Liquid Neoprene to all connections.
22232
a
b
c
d
a-ORANGE Wire - From Electrode on Transom Assembly
b-RED/PURPLE Wire - Connect Other End to Positive(+) Battery Terminal
c-BLACK Wire - From Engine Harness
d-BROWN Wire - From Electrode on Transom Assembly
IMPORTANT: Adjust shift cables as outlined in appropriate Sterndrive Service
Manual.
8. Refer to appropriate Sterndrive Service Manual. Install and adjust drive unit and remote
control shift cables, using hardware retained.
IMPORTANT: After fluid hose installation in the following, bleed power steering
system as outlined in SECTION 1B - Maintenance or refer to appropriate Sterndrive
Service Manual.
9. Connect power steering fluid hoses to control valve (large fitting first) as shown.
CAUTION
Route hoses exactly as shown below. This will help avoid stress on the hose fittings
and will help avoid kinks in the hose.
IMPORTANT: Make hydraulic connections as quickly as possible to prevent fluid
leakage.
IMPORTANT: Be careful not to cross-thread or overtighten fittings.
10. Torque fittings to 23 lb-ft (31 Nm).
73786
a
a-Power Steering Fluid Hose Fittings
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-18 90-861329--1 MARCH 1999
11. Connect battery cables to battery by FIRST connecting POSITIVE (+) battery cable
(usually RED) to POSITIVE (+) battery terminal.
12. Tighten clamps securely.
13. Connect NEGATIVE (–) battery cable (usually BLACK) to NEGATIVE (–) battery
terminal.
14. Tighten clamp securely.
NOTE: Spray terminals with a battery connection sealant to help retard corrosion.
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 2A-19
THIS PAGE IS INTENTIONALLY BLANK
INDEX
MCM 3.0L (181 CID) - ALPHA DRIVE SERVICE MANUAL NUMBER 26
Page 2A-20 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
INDEX
3
A
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-1
ENGINE
Section 3A - 181 cid (3.0L) 4 Cylinder GM Engine
Table of Contents
Torque Specifications 3A-3. . . . . . . . . . . . . . . . . .
Tools 3A-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools 3A-4. . . . . . . . . . . . . . . . . . . . . . .
Lubricants/Sealants/Adhesives 3A-5. . . . . . . . . .
Engine Specifications 3A-5. . . . . . . . . . . . . . . . . .
Cylinder Bore 3A-5. . . . . . . . . . . . . . . . . . . . . .
Piston Clearance 3A-5. . . . . . . . . . . . . . . . . . .
Piston Ring: Compression 3A-5. . . . . . . . . . .
Piston Ring: Oil 3A-6. . . . . . . . . . . . . . . . . . . . .
Piston Pin 3A-6. . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft 3A-6. . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft 3A-6. . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head 3A-7. . . . . . . . . . . . . . . . . . . . . .
Valve System 3A-7. . . . . . . . . . . . . . . . . . . . . .
General 3A-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Identification 3A-8. . . . . . . . . . . . . . . .
Engine Rotation 3A-8. . . . . . . . . . . . . . . . . . . .
Firing Order 3A-9. . . . . . . . . . . . . . . . . . . . . . . .
Priming Engine With Oil 3A-9. . . . . . . . . . . . . . . .
Tool Required 3A-9. . . . . . . . . . . . . . . . . . . . . .
Bearing Failures 3A-10. . . . . . . . . . . . . . . . . . . . .
Piston Failures 3A-12. . . . . . . . . . . . . . . . . . . . . . .
Pre-Ignition 3A-12. . . . . . . . . . . . . . . . . . . . . . .
Detonation 3A-13. . . . . . . . . . . . . . . . . . . . . . . .
Engine Mounts 3A-14. . . . . . . . . . . . . . . . . . . . . . .
Rocker Arm Cover 3A-15. . . . . . . . . . . . . . . . . . . .
Removal 3A-15. . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-15. . . . . . . . . . . . . . . . . . . . . . . .
Push Rod Cover 3A-16. . . . . . . . . . . . . . . . . . . . .
Removal 3A-16. . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-16. . . . . . . . . . . . . . . . . . . . . . . .
Rocker Arm/Push Rod 3A-17. . . . . . . . . . . . . . . .
Removal 3A-17. . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-17. . . . . . . . . . . .
Installation 3A-18. . . . . . . . . . . . . . . . . . . . . . . .
Valve Adjustment 3A-18. . . . . . . . . . . . . . . . . . . . .
Engine Not Running 3A-18. . . . . . . . . . . . . . .
Engine Running 3A-19. . . . . . . . . . . . . . . . . . .
Hydraulic Valve Lifters 3A-20. . . . . . . . . . . . . . . .
Locating Noisy Lifters 3A-20. . . . . . . . . . . . . .
Removal 3A-21. . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-21. . . . . . . . . . . .
Installation 3A-21. . . . . . . . . . . . . . . . . . . . . . . .
Valve Stem Oil Seal/Valve Spring 3A-22. . . . . . .
Replacing Oil Seal (Head Installed) 3A-23. .
Cylinder Head 3A-24. . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-25. . . . . . . . . . . .
Installation 3A-25. . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Valve Conditioning 3A-26. .
Disassembly 3A-26. . . . . . . . . . . . . . . . . . . . . .
Cleaning 3A-26. . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 3A-27. . . . . . . . . . . . . . . . . . . . . . . .
Rocker Arm Studs 3A-28. . . . . . . . . . . . . . . . .
Valve Guide Bore Repair 3A-29. . . . . . . . . . .
Valve Springs - Checking Tension 3A-30. . . .
Valve Seats 3A-30. . . . . . . . . . . . . . . . . . . . . . .
Reassembly 3A-31. . . . . . . . . . . . . . . . . . . . . .
Dipstick Specifications 3A-33. . . . . . . . . . . . . . . .
All Engines 3A-33. . . . . . . . . . . . . . . . . . . . . . .
Oil Pan 3A-34. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-34. . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-34. . . . . . . . . . . . . . . . . . . . . . . .
Oil Pump 3A-35. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-35. . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 3A-35. . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-36. . . . . . . . . . . .
Reassembly 3A-36. . . . . . . . . . . . . . . . . . . . . .
Installation 3A-36. . . . . . . . . . . . . . . . . . . . . . . .
Torsional Damper 3A-37. . . . . . . . . . . . . . . . . . . .
Removal 3A-37. . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-37. . . . . . . . . . . . . . . . . . . . . . . .
Crankcase Oil Seal 3A-39. . . . . . . . . . . . . . . . . . .
Replacing Oil Seal Without Removing
Front Cover 3A-39. . . . . . . . . . . . . . . . . . . . . .
Crankcase Front Cover 3A-40. . . . . . . . . . . . . . .
Removal 3A-40. . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-40. . . . . . . . . . . .
Installation 3A-40. . . . . . . . . . . . . . . . . . . . . . . .
Flywheel and Engine Coupler 3A-41. . . . . . . . . .
Removal 3A-41. . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 3A-41. . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-42. . . . . . . . . . . . . . . . . . . . . . . .
Rear Main Oil Seal 3A-43. . . . . . . . . . . . . . . . . . .
Removal 3A-43. . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-43. . . . . . . . . . . .
Installation 3A-43. . . . . . . . . . . . . . . . . . . . . . . .
Main Bearings 3A-44. . . . . . . . . . . . . . . . . . . . . . .
Inspection 3A-44. . . . . . . . . . . . . . . . . . . . . . . .
Checking Clearances 3A-45. . . . . . . . . . . . . .
Main Bearing Replacement 3A-46. . . . . . . . .
Connecting Rod Bearings 3A-47. . . . . . . . . . .
Inspection and Replacement 3A-47. . . . . . . .
Connecting Rod/Piston Assembly 3A-49. . . . . .
Removal 3A-49. . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 3A-49. . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-50. . . . . . . . . . . .
Reassembly 3A-51. . . . . . . . . . . . . . . . . . . . . .
Installation 3A-53. . . . . . . . . . . . . . . . . . . . . . . .
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-2 90-861329--1 MARCH 1999
Table of Contents (continued)
Crankshaft 3A-55. . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-55. . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-56. . . . . . . . . . . .
Installation 3A-56. . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft Sprocket 3A-57. . . . . . . . . . . . . . . . . .
Removal 3A-57. . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-57. . . . . . . . . . . . . . . . . . . . . . . .
Camshaft 3A-58. . . . . . . . . . . . . . . . . . . . . . . . . . .
Measuring Lobe Lift 3A-58. . . . . . . . . . . . . . . .
Removal 3A-58. . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 3A-59. . . . . . . . . . . . . . . . . . . . . . . .
Camshaft Gear Replacement 3A-60. . . . . . .
Installation 3A-60. . . . . . . . . . . . . . . . . . . . . . . .
Camshaft Bearings 3A-62. . . . . . . . . . . . . . . . . . .
Removal 3A-62. . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 3A-62. . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-62. . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Block 3A-64. . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-64. . . . . . . . . . . .
Oil Filter By-Pass Valve 3A-68. . . . . . . . . . . . . . .
Inspection and/or Replacement 3A-68. . . . . .
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-3
Torque Specifications
Fastener Location lb-in. lb-ft Nm
Camshaft Sprocket Bolts 80 9
Connecting Rod Cap Nuts 45 61
Cylinder Head Bolts 90
1
122
Distributor Clamp 20 27
Engine Coupler to Flywheel 35 47
Flywheel Housing to Block 21 28
Flywheel to Crankshaft Bolts 65 88
Front Cover Bolts 27-35 3.4
Front Mount to Block 21 28
Main Bearing Cap Bolts 65 88
Center 20-25
2
27-34
Manifold to Head
Outer 15-20 20-27
Oil Pan Bolts-Crankcase 80 9
Oil Pan Bolts-to Front Cover 45 5
Oil Pan Studs to Oil Seal Retainer or Crankcase 15 1.7
Oil Pump Cover 72 8
Oil Pump to Block 120 14
Oil Pump Pickup 60 7
Rocker Arm Cover and Bolts 40 4.5
Rocker Arm Nuts
3/4 Turn Down From Zero
Lash
Push Rod Cover Bolts 40 4.5
Crankshaft Rear Oil Seal Retainer Nuts 150-180 17-20
Spark Plugs 22 30
Starter Motor to Block 37 50
Timing Gear Cover 72 8
Torsional Damper Bolt 50 68
Water Pump to Block 15 20
1
Retorque after first 20 hours of operation.
2
Retorque after first start-up.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-4 90-861329--1 MARCH 1999
Tools
Description Parts Number
Piston Ring Expander 91-24697
Torch Lamp 91-63209
Special Tools
KENT MOORE SPECIAL TOOLS
Kent-Moore Special Tools
29784 Little Mack
Roseville, MI 48066
Phone: (313) 574-2332
Description Parts Number
Valve Spring Compressor (Head on) J5892
Valve Spring Compressor (Head off) J8062
Valve Stem Seal Tester J23738-A
Valve Guide Reamer (Standard) J8814
Valve Guide Reamer (.015 in. oversize) J5830-02
Rocker Arm Stud Remover J5802-01
Rocker Arm Stud Installer J6880
Stud Bore Reamer (.003 in. oversize) J5715
Stud Bore Reamer (.013 in. oversize) J6036
Carbon Remover Brush J8089
Piston Support Tool J5910-04
Piston Pin Tool J24086-B
Piston Ring Groove Cleaner J3936-03
Piston Ring Compressor J8037
Connecting Rod Guide Tool (3/8-24) J5239
Cylinder Bore Checker J8087
Oil Pump Suction Pipe Installer J8369
Timing Cover Seal Aligner J23042-B
Cam Lobe Lift Indicator J8520
Camshaft Bearing Installer/Remover Tool J6098-01
Distributor Shaft Lower Bearing Installer/
Remover
J9534-01
Pulley Hub Puller J6978-E
Pulley Hub Installer J5590
Universal Torsional Damper Remover J24420-B
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-5
Lubricants/Sealants/Adhesives
Description Parts Number
Quicksilver Perfect Seal 92-34227--1
Quicksilver 2-4-C Marine Lubricant with
Teflon
92-825407A3
Quicksilver RTV Sealer 92-809826
Engine Specifications
NOTICE
Unit Of Measurement: U.S. Inches (Millimeters)
Model 3.0L
Displacement 181 cid (3.0L)
Cylinder Bore
Diameter 3.9995-4.0025 (101.588-101.790)
Production .0005 (0.012) Max
Out of Round
Service .002 (0.05) Max
Production
Thrust
Side
.0005 (0.012) Max
Taper
Production
Relief Side .0005 (0.012) Max
Service .001 (0.02) Max
Piston Clearance
Production .0025-.0035 (0.064-0.088) Max
Service .0035 (0.08) Max
Piston Ring: Compression
Top
Groove Clearance
Production
2nd
.0012-.0029 (0.030-0.073)
Service .003 (0.09) Max
Top
Gap
Production
2nd
.010-.020 (0.254-0.762)
Service .035 (0.88) Max
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-6 90-861329--1 MARCH 1999
Piston Ring: Oil
Production .001-.006 (0.026-0.152)
Groove
Clearance
Service
Limit
.007 (0.17) Max
Production .010-.030 (0.254-0.762) Max
Gap
Service
Limit
.040 (1.01) Max
Piston Pin
Diameter .9270-.9271 (23.546-23.550)
Production .0003-.0006 (0.008-0.016)
Clearance
Service
Limit
.001 (0.02) Max
Fit in Rod .0008-.0019 (0.020-0.050) Interference
Crankshaft
Diameter 2.2979-2.294 (58.367-58.404)
Main
Production .0002 (0.005) Max
Journal
Taper
Service .001 (0.02) Max
Out of
Production .0002 (0.005) Max
Out of
Round
Service .001 (0.02) Max
Production No.1-No.4 .001-.0024 (0.025-0.060)
Main
Service No.5 .0016-.0035 (0.041-0.088)
Bearing
Clearance
Production No.1-No.4 .001-.0025 (0.03-0.06)
Clearance
Service No.5 .002-.0035 (0.05-0.08)
Crankshaft End Play .002-.006 (0.05-0.15)
Diameter 2.09980-20995 (53.289-53.327)
Production .0003 (0.007) Max
Crankpin
Taper
Service .001 (0.02) Max
Out of
Production .0002 (0.51) Max
Out of
Round
Service .001 (0.02) Max
Rod
Production .0017-.0027 (0.044-0.0686)
Bearing
Clearance
Service
Rod Size Clearance .006-.017 (0.153-0.4318) Max
Camshaft
Intake .2529 (6.425)
Lobe Lift (Max.)
Exhaust .2529 (6.425)
Journal Diameter 1.8677-18697 (47.440-47.490)
Camshaft End Play .003-.008 (0.08-0.2032) Max
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-7
Cylinder Head
Gasket Surface Flatness
.003-.008 in any 6 in. (152) or .007
(0.15) Overall Max
Valve System
Lifter Hydraulic
Rocker Arm Ratio 1.75 to 1
Collapsed Tappet Gap 3/4 Turn Down from Zero Lash
Intake 45°
Face Angle
Exhaust 45°
Seat Angle (Intake & Exhaust) 46°
Seat Runout (Intake & Exhaust) .002 (0.05) Max
Intake 1/16 (.0625 in.) (1.16 mm)
Seat Width
Exhaust 1/16-5/64 [.0625-.07812 in.] (1.6-2.0 mm)
Intake .0010-.0027 (0.025-0.069)
Stem
Production
Exhaust .0007-.0027 (0.018-0.069)
Stem
Clearance
Intake .003 (0.09) Max
Service
Exhaust .004 (0.11) Max
Free Length 2-1/16 in. (52 mm)
Valve
Closed
100-110 lb. (136-149 N) at 1-19/32 in. (41 mm)
Spring
Pressure
Valve
Open
208-220 lb. (282-300 N) at 1-7/32 in. (31 mm)
Installed
±
Intake
Height ±
.031(8)
Exhaust
(1/32) 1.6562 (42)
Internal Damper None
General
Some of the repairs in this section must be completed with engine removed from boat.
Engine removal depends upon type of repair and boat design. Place engine on repair stand
for major repairs.
When engine removal is not required, make certain that battery cables are disconnected
at the battery prior to performing any on-board engine repair procedure.
Lubricate all moving parts (during reassembly) with engine oil. Apply Quicksilver Perfect
Seal on threads of and under heads of cylinder head bolts, and on threads of all cylinder
block external bolts, screws and studs.
Model No. of Cylinders cu-in./liters Displacement
MCM 3.0L 4 181 (3L)
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-8 90-861329--1 MARCH 1999
Engine Identification
The MerCruiser Model can be determined by looking at the LAST TWO LETTERS of the
engine code stamped into the cylinder block. This code number is stamped on all
MerCruiser power packages and replacement partial engines, but not replacement cylinder
block assemblies.
If the engine serial number and/or model decals are missing, the engine code letters may
help in determining the engine models.
a
74520
G.M. Engine Code Location 3.0L -
RX (12-3/4 in. or 324 mm flywheel) - S/N 0L096999 and below
RP (14 in. or 356 mm flywheel) - S/N 0L097000 and above
a-4 Cylinder-In-Line Engine Code (Next To Distributor)
Engine Rotation
Engine rotation terminology at times has caused confusion. To clarify, engine rotation is
determined by observing flywheel rotation from the rear (transmission or sterndrive end) of
the engine looking forward (water pump end).
PROPELLER ROTATION IS NOT NECESSARILY THE SAME as engine rotation. Do not
rely on propeller rotation in determining engine rotation.
72001
a
a-Left-Hand Rotation (CCW)
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-9
Firing Order
50683
Firing Order 1-3-4-2
Priming Engine With Oil
IMPORTANT: This applies to all power packages that have not been run within 6
months, replacement of partial engines or after rebuilding an engine.
Tool Required
71089
Remote Starter Kit (91-52024A1)
1. Fill crankcase to proper level with the recommended engine oil.
2. Remove spark plugs.
3. Leave ignition key in “OFF” position.
4. Connect remote starter switch to large 12 V terminal (RED battery cable) and small ter-
minal (RED/YELLOW) wire on starter motor.
a. If remote starter switch is not available, disconnect PURPLE wire from ignition coil
before using key switch to crank the engine over. Tape terminal on PURPLE wire to
prevent it from touching ground.
5. Crank engine for 15 seconds, then allow starter motor to cool down for 1 minute. This
should prevent starter motor from overheating.
6. Repeat this process until a total of 45 seconds of cranking time is achieved.
7. Remove remote starter switch.
a. If key switch was used, reconnect PURPLE wire to ignition coil.
8. Install spark plugs and wires
9. Supply cooling water to seawater pump and start motor.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-10 90-861329--1 MARCH 1999
Bearing Failures
70436
a
b
Scratched By Dirt
a-Scratches
b-Dirt Imbedded In Bearing Material
70436
a
Tapered Journal
a-Overlay Gone From Entire Surface
70436
a
Lack Of Oil
a-Overlay Worn Off
70436
a
Radius Ride
a-Worn Area
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-11
70436
a
Improper Seating
a-Bright Or Polished Sections
70436
a
Fatigue Failure
a-Craters or Pockets
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-12 90-861329--1 MARCH 1999
Piston Failures
Pre-Ignition
Pre-ignition is abnormal fuel ignition, caused by combustion chamber hot spots. Control of
the start of ignition is lost, as combustion pressure rises too early, causing power loss and
rough running. The upward motion on the piston is opposed by the pressure rise. This can
result in extensive damage to the internal parts from the high increase in combustion cham-
ber temperature.
72424
Pre-Ignition Damage
CAUSES
1. Hot spots in the combustion chamber from glowing deposits (due in turn to the use of
improper oils and/or fuels).
2. Overheated spark plug electrodes (improper heat range or defective plug).
3. Any other protuberance in the combustion chamber, such as an overhanging piece of
gasket, an improperly seated valve or any other inadequately cooled section of material
which can serve as a source.
Engine failures that result from the foregoing conditions are beyond the control of Mercury
Marine. No warranty will apply to failures which occur under these conditions.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-13
Detonation
Detonation, commonly called fuel knock,spark knock or carbon knock, is abnormal
combustion of the fuel which causes the fuel to explode violently. The explosion causes
overheating or damage to the spark plugs, pistons, valves and, in severe cases, results in
pre-ignition.
CAUSES
IMPORTANT: Use of improper fuels will cause engine damage and poor performance.
1. Use of low octane gasoline is one of the most common causes of detonation. Even with
high octane gasoline, detonation could occur if engine maintenance is neglected.
2. Over-advanced ignition timing.
3. Lean fuel mixture at or near full throttle (could be caused by carburetor or leaking intake
manifold).
4. Cross-firing spark plugs.
5. Excess accumulation of deposits on piston and/or combustion chamber (results in
higher compression ratio).
6. Inadequate cooling of engine by deterioration of cooling system.
Engine failures that result from the foregoing conditions are beyond the control of
MerCruiser. No warranty will apply to failures which occur under these conditions.
72425
Detonation Damage
72315
a
b
c
d
a-Spark Occurs
b-Combustion Begins
c-Combustion Continues
d-Detonation Occurs
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-14 90-861329--1 MARCH 1999
Engine Mounts
74275
Front Mount
72318
a
Rear Mount/Flywheel Housing
a-Press Mount Out With Press
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-15
Rocker Arm Cover
Removal
It may be necessary to remove exhaust manifold before removing rocker arm cover. Refer
to SECTION 7B for removal.
1. Disconnect crankcase ventilation hose.
2. Remove any items that interfere with the removal of rocker arm covers.
IMPORTANT: DO NOT pry rocker arm cover loose. Gaskets, which may adhere to cyl-
inder head and rocker arm cover, may be loosened by bumping end of rocker cover
from the rear with palm of hand or a rubber mallet.
3. Remove rocker arm cover.
Installation
1. Clean sealing surfaces on cylinder head and rocker arm cover with degreaser.
2. Place new rocker arm cover gasket in position in rocker arm cover.
3. Install rocker arm cover. Torque bolts to 40 lb-in. (4.5 Nm).
4. Install exhaust manifolds.
5. Install any items which were removed to allow removal of rocker arm covers.
6. Connect crankcase ventilation hose to rocker arm cover.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-16 90-861329--1 MARCH 1999
Push Rod Cover
Removal
1. Remove the pushrod cover bolts.
2. Remove the pushrod cover.
3. Remove the gasket.
76247
Installation
1. Clean sealing surfaces on pushrod cover with degreaser.
2. Install new pushrod cover gasket in position.
3. Install pushrod cover. Torque bolts to 40 lb-in. (4.5 Nm).
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-17
Rocker Arm/Push Rod
74287
e
a
b
c
d
Valve Mechanism
a-Nut
b-Ball Unit
c-Rocker Arm
d-Push Rod
e-Rocker Arm Stud
Removal
NOTE: When servicing only one cylinder’s rocker arms, bring that cylinder’s piston up to
TDC before removing rocker arms. When servicing all rocker arms, bring No. 1 piston up
to TDC before removing rocker arms.
1. Remove rocker arm covers as outlined.
2. Remove rocker arm assemblies and push rods.
76232
IMPORTANT: Place rocker arm assemblies and push rods in a rack for reassembly
in their original locations.
Cleaning and Inspection
1. Clean parts with solvent and dry with compressed air.
2. Inspect all contact surfaces for wear. Replace all damaged parts.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-18 90-861329--1 MARCH 1999
Installation
IMPORTANT: When installing rocker arms and rocker arm balls, coat bearing sur-
faces of rocker arms and rocker arm balls with engine oil.
1. Install push rods in their original locations. Be sure push rods seat in lifter socket.
2. Install rocker arms, rocker arm balls and rocker arm nuts in their original locations.
76232
3. Turn nut down 1/4 additional turn and pause 10 seconds until engine runs smoothly.
Repeat additional 1/4 turns, pausing 10 seconds each time, until nut has been turned
down 3/4 turn from zero lash position.
4. Adjust carburetor idle speed and mixture.
Valve Adjustment
Engine Not Running
With valve cover removed, adjust valves when lifter is on low part of camshaft lobe, as
follows:
1. Crank engine with starter or turn over in normal direction of rotation until mark on
torsional damper lines up with center 0” mark on timing tab, and engine is in No. 1 firing
position. This may be determined by placing fingers on No. 1 valve as mark. If valves
move as mark comes up to timing tab, engine is in No.4 firing position and should be
turned over one more time to reach No. 1 position.
50770
Typical
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-19
2. With engine in No. 1 firing position as determined above, the following valves may be
adjusted:
No. 1 Cylinder - Exhaust and Intake
No. 2 Cylinder - Intake
No. 3 Cylinder - Exhaust
No. 4 Cylinder - Intake
3. Loosen adjusting nut until lash is felt at push rod, then tighten adjusting nut until all lash
is removed. This can be determined by moving push rod up and down while turning
adjusting nut until all play is removed.
72300
4. Hydraulic lifters can be adjusted by tightening adjustment nut an additional 3/4-turn.
Valve lash should be checked after engine has run and reached operating temperature.
5. Crank engine one revolution until pointer “0” mark and torsional damper mark are again
in alignment. This is No. 4 firing position. With engine in this position, the following valves
may be adjusted:
No. 2 Cylinder - Exhaust
No. 3 Cylinder - Intake
No. 4 Cylinder - Exhaust
6. Repeat steps 3-4 to adjust other valves.
7. Install Distributor cap, spark plug wires and coil lead.
8. Install rocker arm cover; torque to 40 lb-in. (4.5 Nm).
Engine Running
Following procedure should be completed only if readjustment is required.
1. Run engine until it reaches normal operating temperature, then remove valve cover.
2. With engine running at idle, loosen valve rocker arm nut until valve rocker arm starts to
clatter.
3. Turn rocker arm nut down slowly until clatter just stops. This is zero lash position.
4. Tighten nut 1/4 additional turn and pause 10 seconds until engine runs smoothly. Repeat
additional 1/4 turns, pausing 10 seconds each time, until nut has been tightened 3/4 turn
from zero lash position.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-20 90-861329--1 MARCH 1999
IMPORTANT: The following preload adjustment must be done slowly to allow lifter to
adjust itself, thus preventing possibility of the valve head contacting the top of
piston, which may result in internal damage and/or bent push rods.
5. Repeat Steps 2-4 to adjust other valves.
6. Install rocker arm cover, torque to 40 lb-in. (4.5 Nm).
7. Adjust carburetor idle mixture and idle speed. Check for leaks.
Hydraulic Valve Lifters
Hydraulic valve lifters require little attention. Lifters are extremely simple in design.
Normally, readjustments are not necessary and servicing requires only that care and
cleanliness be exercised in the handling of parts.
Locating Noisy Lifters
Locate a noisy valve lifter by using a piece of garden hose approximately 4 ft (1.2 m) in
length. Place one end of hose near end of each intake and exhaust valve, with other end
of hose to the ear. In this manner, sound is localized, making it easy to determine which lifter
is at fault.
Another method is to place a finger on face of valve spring retainer. If lifter is not functioning
properly, a distinct shock will be felt when valve returns to its seat.
General types of valve lifter noise are as follows:
1. Hard rapping noise - usually caused by plunger becoming tight in bore of lifter body so
that return spring cannot push plunger back up to working position. Probable causes
are:
Excessive varnish or carbon deposit, causing abnormal stickiness.
Galling or pickup between plunger and bore of lifter body, usually caused by an abra-
sive piece of dirt or metal wedged between plunger and lifter body.
2. Moderate rapping noise - probable causes are:
Excessively high leakdown rate.
Leaky check valve seat.
Improper adjustment.
3. General noise throughout valve train - this will, in most cases, be a definite indication
of insufficient oil supply or improper adjustment.
4. Intermittent clicking - probable causes are:
A microscopic piece of dirt momentarily caught between ball seat and check valve ball.
In rare cases, ball itself may be out of round or have a flat spot.
Improper adjustment.
In most cases, where noise exists in one or more lifters, all lifter units should be removed,
disassembled, cleaned in solvent, reassembled and reinstalled in engine. If dirt, corrosion,
carbon, etc., exists in one unit, it probably exists in all units. It would only be a matter of time
before all lifters caused trouble.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-21
Removal
1. Remove as previously outlined:
a. Rocker arm covers.
b. Push rod cover.
IMPORTANT: Keep valve push rod and hydraulic lifter from each valve together as a
matched set and mark or store them so they can be reinstalled in the same location
later.
c. Rocker arm assemblies and push rods.
2. Make matching marks on all lifters as to location and orientation in bores, to allow reas-
sembly in exact position on camshaft lobes (so that the rollers bearing and roller will roll
in the same direction on the same lobe, if reused). Remove valve lifters.
Cleaning and Inspection
1. Thoroughly clean all parts in cleaning solvent and inspect them carefully.
2. If any parts are damaged or worn, entire lifter assembly should be replaced.
3. If outer lifter body wall is scuffed or worn, inspect cylinder block lifter bore.
4. If push rod seat is scuffed or worn, inspect push rod.
Installation
IMPORTANT: It is recommended that the engine oil be changed and a new oil filter be
installed whenever servicing valve lifters or camshaft
IMPORTANT: Before installing lifters, coat the lifter with engine oil. If new lifters or
a new camshaft have been installed, an additive containing EP lube (such as General
Motors Cam and Lifter Prelube or equivalent) should be poured over camshaft lobes
before installing lifters.
IMPORTANT: DO NOT install used valve lifters if a new camshaft has been installed.
1. Install valve lifters into bores.
2. Install push rod cover, using new gaskets and torque to specification.
3. Install distributor, positioning rotor to number 1 cylinder position, then connect primary
lead at coil.
4. Install distributor cap and spark plug wires.
5. Adjust valves to specifications.
6. Install rocker arm cover, torque tp 40 lb-in. (4.5 Nm).
7. Adjust ignition timing, carburetor idle speed and mixture.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-22 90-861329--1 MARCH 1999
Valve Stem Oil Seal/Valve Spring
76248
a
b
c
d
e
f
a-Keys (2 per Valve)
b-Cap
c-Seal
d-Valve Spring Shield
e-Valve Spring
f-Valve
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-23
Replacing Oil Seal (Head Installed)
1. Remove rocker arm cover.
2. Remove spark plug, rocker arm and push rod on cylinder to be serviced.
3. Place piston for that cylinder at TDC to prevent valves from dropping into the cylinder.
4. Compress valve spring with tool (J-5892) and remove valve keys, valve spring cap,
spring shield and valve spring.
72881
a
b
a-Valve Spring Compressor (J-5892)
b-Rocker Arm Nut
5. Remove valve stem oil seal.
6. To install, set valve spring, (close, coiled end of spring is installed against cylinder head)
valve shield and valve cap in place. Compress spring with tool (J-5892) and install oil
seal in lower groove of stem, making sure that seal is flat and not twisted.
NOTE: A light coat of oil on seal will help prevent twisting when compressor tool is released.
IMPORTANT: Do not turn crankshaft while valve springs, retainers, and locks are
removed or valves will fall into cylinder.
7. Install valve keys and release compressor tool. Be sure that keys seat properly in upper
groove of valve stem.
8. Install and adjust valve mechanism.
9. Install push rods and rocker arm assemblies.
10. Torque rocker arm nuts as described in “Specifications.”
11. Install rocker arm cover and torque to 40 lb-in. (4.5 Nm).
12. Install spark plug and torque to 22 lb-ft (30 Nm).
13. Repeat steps 2 through 8 for other cylinders.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-24 90-861329--1 MARCH 1999
Cylinder Head
1
2
6
5
3
4
9
10
7
8
Cylinder Head Torque Sequence
1. Drain engine cooling system.
2. Remove as outlined:
a. Exhaust manifolds.
b. Intake manifold.
c. Rocker arm cover.
d. Pushrod cover.
e. Rocker arm assemblies and push rods (keep in order for reassembly in their original
locations).
76232
f. Any components attached to front or rear of cylinder head.
g. Spark plugs.
h. Head bolts.
CAUTION
The head gasket may be holding cylinder head to block. Use care when prying off
cylinder heads. DO NOT damage gasket surfaces. DO NOT drop cylinder heads.
3. Place cylinder head on wooden blocks to prevent damage to gasket surfaces.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-25
Cleaning and Inspection
1. Clean gasket material and sealer from engine block and cylinder heads.
2. Inspect sealing surfaces for deep nicks and scratches.
3. Inspect for corrosion around cooling passages.
4. Clean head bolt threads and engine block bolt hole threads, making sure no dirt, old oil
or coolant remains.
Installation
CAUTION
When using ribbed stainless steel head gaskets, apply a thin coating of Quicksilver
Perfect Seal to both sides of gasket. Too much sealer may hold gasket away from
head or block causing leakage. DO NOT use sealer on graphite composition head
gaskets.
1. Place head gasket in position over dowel pins.
2. Carefully set cylinder head in place over dowel pins.
3. Coat threads of head bolts with Quicksilver Perfect Seal and install finger-tight.
4. Torque head bolts to 90 lb-ft (122 Nm).
5. Install push rods, rocker arm assemblies and lifter restrictors in their original positions.
6. Torque rocker arm nuts to 20 lb-ft (27 Nm).
7. Install as outlined:
a. Intake/exhaust manifold.
b. Rocker arm cover.
c. Spark plugs.
d. Any components removed from front or rear of cylinder heads.
8. Follow procedures in SECTION 6A or 6B of this manual:
Seawater Cooled Models: Provide for adequate water supply to seawater pickup (see
SECTION 6A).
Closed Cooled Models: Refill closed cooling section (see SECTION 6B) and provide ade-
quate water supply to seawater pickup.
CAUTION
Ensure that cooling water supply is available before starting the engine.
9. Start engine, set timing, set idle speed and check for leaks.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-26 90-861329--1 MARCH 1999
Cylinder Head and Valve Conditioning
Disassembly
1. Using valve spring compressor, compress valve spring (J-8062) and remove valve
locks. Slowly release tool.
2. Remove all valve components.
3. Remove valves from cylinder head and place in a rack, in order, for reassembly in their
original locations.
72333
a
a-Valve Spring Compressor (J-8062)
Cleaning
1. Clean push rods and rocker arm assemblies.
2. Clean carbon from valves using tool (J-80890).
3. Clean gasket material from cylinder head mating surfaces.
4. Clean all carbon from combustion chambers and valve ports using carbon remover
brush.
74274
a
a-Carbon Remover Brush (J-8089)
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-27
5. Thoroughly clean valve guides with valve guide cleaner (J-8101).
74286
a
a-Valve Guide Cleaner (J-8101)
Inspection
1. Inspect cylinder head for cracks in exhaust ports, water jackets and combustion cham-
bers (especially around spark plug holes and valve seats). Replace heads if any cracks
are found.
2. Inspect cylinder head gasket surface for burrs, nicks, erosion or other damage. Check
flatness of cylinder head gasket surface, using a machinists straight edge and feeler
gauges as shown. Take measurements diagonally across head (both ways) and straight
down center head. Refer to “Specifications.”
72885
b
a
a-Straight Edge
b-Feeler Gauge
IMPORTANT: Cylinder head-to-block gasket surface should be resurfaced if warped
more than specified. When head resurfacing is required, cylinder head-to-intake
manifold gasket surface on head must be milled to provide proper alignment
between intake manifold and head.
3. Inspect valves for burned heads, cracked faces or damaged stems.
IMPORTANT: Excessive valve stem to bore clearance will cause excessive oil
consumption and possible valve breakage. Insufficient clearance will result in noisy
and sticky valves.
4. Measure valve stem clearance as follows:
a. Attach a dial indicator to cylinder head, positioning it against the valve stem and
close to the valve guide.
b. Holding valve head off seat about 1/16 in. (2 mm), move valve stem back and forth
in direction shown. Compare stem clearance with specifications.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-28 90-861329--1 MARCH 1999
c. If clearance exceeds specifications, it will be necessary to ream valve guides for
oversized valves, as outlined under Valve Guide Bore Repair.
72336
c
b
a
a-Valve Stem
b-Dial Indicator
c-Valve Guide
Rocker Arm Studs
Rocker arm studs with damaged threads or with loose fit in cylinder heads should be
replaced with new, oversize studs. Studs may be installed after reaming holes as follows:
1. Drain water from cylinder block.
2. Remove old stud by placing Tool J-5802-1 over stud, installing nut and flat washer and
turning the nut to remove stud.
74288
a
a-Tool J-5802-01
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-29
3. Ream hole for oversize stud with Tool J-5715 for .003 in. oversize or Tool J-6036 for .013
in. oversize.
74289
a
a-Reamer Tool J-5715
IMPORTANT: Do not attempt to install an oversize stud without reaming stud hole.
4. Coat press-fit area of stud with Perfect Seal. Install new stud, using Tool J-6880 as a
guide. Gauge should contact head.
Valve Guide Bore Repair
IMPORTANT: Be sure to measure valve stem diameter of both the intake and exhaust
valve, as valve stem diameter may or may not be the same for both valves.
If .015 in. oversize valve stems are required, ream valve guide bores for oversize valves,
as follows:
1. Measure valve stem diameter of old valve being replaced and select proper size valve
guide reamer from chart below.
2. Ream valve guide bores, as shown.
72886
3. Remove the sharp corner created by reamer at top of valve guide.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-30 90-861329--1 MARCH 1999
Valve Springs - Checking Tension
Using valve spring tester, as shown, check valve spring tension with dampers removed.
Refer to “Specifications.”
IMPORTANT: Springs should be replaced if not within 10 lbs. (44 N) of specified
tension.
a
b
72308
a-Valve Spring Tester (J-8056)
b-Torque Wrench
Valve Seats
Valve seat reconditioning is very important, since seating of valves must be perfect for
engine to deliver maximum power and performance.
Another important factor is valve head cooling. Good contact between each valve and its
seat in head is important to ensure that heat in valve head will be properly dispersed.
Several different types of equipment are available for reseating valve seats. Equipment
manufacturers recommendations should be followed carefully to attain proper results.
Regardless of type of equipment, however, it is essential that valve guide bores be free from
carbon or dirt to achieve proper centering of pilot in valve guide and ensure concentricity.
72338
a
a-Check Valve Seat Concentricity
Valves that are pitted must be refaced to the proper angle. Valve stems which show exces-
sive wear or valves that are warped excessively must be replaced. When a valve head that
is warped excessively is refaced, a knife edge will be ground on part or all of the valve head
due to the amount of metal that must be removed to completely reface. Knife edges lead
to breakage, burning or pre-ignition due to heat localizing on this knife edge. If the edge of
the valve head (margin) is less than 1/32 in. (0.8 mm) after grinding, replace the valve.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-31
Several different types of equipment are available for refacing valves. The recommendation
of the manufacturer of the equipment being used should be carefully followed to attain
proper results.
50695
Exhaust Intake
a-.372 In. (9.45 mm)
b-1/32 [.031] In. (0.79 mm) Min.
c-.341 In. (8.16 mm)
d-1/32 [.031] In. (0.79 mm) Min.
Reassembly
1. Lubricate valve guides and valve stems with engine oil.
2. Install each valve in the port from which it was removed or to which it was fitted.
3. Install valve guide seal (intake valve only) over valve stem and push down until seated
against head.
4. Set valve spring (with damper installed) and cap in place.
5. Place retainer on intake valve and/or rotator on exhaust valve.
6. While compressing valve spring with valve spring compressor, install oil seal in lower
groove of valve stem, making sure seal is not twisted. A light coating of oil will help
prevent twisting.
72884
a
V6 Shown
a-Valve Spring Compressor (J-8062)
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-32 90-861329--1 MARCH 1999
7. Install valve locks (grease may be used to hold them in place) and slowly release tool,
making sure locks seat properly in upper grooves of valve stem.
76249
1
2
3
4
5
6
7
9
8
1
1-Valve Locks
2-Retainer
3-Rotator
4-Cap
5-Valve Guide Oil Seal
6-Valve Stem Oil Seal
7-Outer Spring
8-Intake Valve
9-Exhaust Valve
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-33
8. Check installed height of valve springs using a narrow, thin scale. Measure from spring
seat to top of valve spring, as shown. If measurement exceeds specified height, install
a valve spring shim and recheck. DO NOT shim valve springs to give an installed height
less than the minimum specified.
05037
72339
a
b
Checking Valve Spring Installed Height
a-Cut Out This Portion
b-Valve Spring Installed Height
Dipstick Specifications
All Engines
NOTICE
Unit Of Measurement: U.S. inches (millimeters)
1/2
(13)
25-7/16
(646)
3/4
(19)
26-7/8
(682)
a
b
72887
41092-1 MCM
a-Full
b-Add
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-34 90-861329--1 MARCH 1999
Oil Pan
a
a-Oil Pan Gasket
Removal
1. Disconnect battery.
NOTE: Removal of engine from boat may be required.
2. Drain crankcase oil.
3. Remove starter motor.
4. Remove oil pan screws, oil pan and gasket(s).
Installation
1. Clean sealing surfaces of engine block and oil pan.
2. Apply a small amount of Quicksilver RTV Sealer to joints of rear seal retainer and joints
of front cover.
IMPORTANT: Quicksilver RTV Sealer sets up in about 15 minutes. Be sure to com-
plete assembly promptly.
3. Install oil pan gasket in position as shown.
NOTE: A one-piece oil pan gasket may be reused if it is still pliable and is not cracked, torn
or otherwise damaged.
4. Install oil pan. Starting from the center and working outward in each direction, tighten
1/4-20 threaded fasteners to 80 lb-in. (9 Nm) and 5/16-18 threaded fasteners to 165 lb-
in. (19 Nm).
5. Install dipstick tube and dipstick.
6. Fill crankcase with required quantity of oil of specified viscosity. See SECTION 1B
“Maintenance.”
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-35
Oil Pump
The oil pump consists of two gears and a pressure regulator valve enclosed in a two-piece
housing. Oil pump is driven by distributor shaft which is driven by a helical gear on camshaft.
Removal
1. Remove oil pan as previously outlined.
2. Remove gasket carefully as the one-piece gasket for the oil pan may be reused if still
pliable and not cracked, torn, etc.
3. Remove oil pump.
76234
a
a-Oil Pump
Disassembly
1. Remove pump cover.
IMPORTANT: Mark gear teeth for reassembly with same teeth indexing.
2. Remove idler gear and drive gear from pump body.
3. Remove retaining pin, spring, and pressure regulator valve from pump cover.
IMPORTANT: Do not remove pickup screen and pipe assembly, unless replacement
is necessary. Loss of press fit condition could result in an air leak and loss of oil pres-
sure.
IMPORTANT: Do not disturb pickup screen on pipe. This is serviced as an assembly.
4. If pickup screen and pipe assembly requires replacement, mount pump in a soft-jawed
vise and extract pipe from pump.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-36 90-861329--1 MARCH 1999
Cleaning and Inspection
1. Wash all parts in cleaning solvent and dry with compressed air.
2. Inspect pump body and cover for cracks or excessive wear.
3. Inspect pump gears for damage and excessive wear.
4. Check for loose drive gear shaft in pump body.
5. Inspect inside of pump cover for wear that would permit oil to leak past ends of gears.
IMPORTANT: Pump gears and body are not serviced separately. If pump gears or
body are damaged or worn, replacement of entire oil pump assembly is necessary.
6. Inspect pickup screen and pipe assembly for damage to screen and pipe.
7. Check pressure regulator valve for fit.
Reassembly
CAUTION
Be careful of twisting, shearing or collapsing pipe while installing in pump. Pickup
screen must be parallel to oil pan bottom when oil pump is installed.
If pickup screen and pipe assembly was removed, mount pump in a soft-jawed vise, apply
Quicksilver Perfect Seal to end of new pipe and, using oil pump suction pipe installer
(J-21882), tap the pipe in place with a hammer.
IMPORTANT: Oil internal parts liberally before installation.
1. Install pressure regulator valve and related parts.
2. Install drive gear in pump body.
3. Install idler gear in pump body with smooth side of gear toward pump cover opening.
Align marks made in disassembly.
4. Fill gear cavity with engine oil.
5. Install pump cover and torque attaching bolts to 80 lb-in. (9 Nm).
Installation
1. Install pump to rear main bearing.
2. Torque oil pump bolt to 65 lb-ft (88 Nm).
3. Install oil pan as outlined. The one-piece gasket for the oil pan may be reused if still
pliable and not cracked, torn, etc.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-37
Torsional Damper
Removal
1. Support front of engine (if in boat) with overhead hoist.
2. Remove front mounting bracket and drive belt. Remove retaining bolt, if equipped.
3. Install tool J-6978-E to balancer and turn puller. Remove drive pulley, then remove
torsional damper retaining bolt.
IMPORTANT: DO NOT use a universal claw type puller to remove torsional damper
(in next step) as outside ring of torsional damper is bonded in rubber to the hub and
use of claw type puller may break the bond.
4. Remove torsional damper with torsional damper remover and installer.
72890
a
a-Torsional Damper Remover and Installer (J-6978-E)
Installation
IMPORTANT: The inertia weight section of torsional damper is assembled to the hub
with a rubber type material. The installation procedure (with proper tool) must be
followed or movement of the inertia weight on the hub will destroy the tuning of the
torsional damper.
1. Replace key in crankshaft if it is damaged.
2. Coat seal surface of torsional damper with engine oil.
NOTE: If a suitable torsional damper installer installation tool is not available, use a block
of wood as a driver. Be very careful not to cause pulley or weight to shift on their rubber
mounts.
3. Install torsional damper on crankshaft, using torsional damper remover and installer as
follows:
a. Install appropriate end of threaded rod into crankshaft.
IMPORTANT: Be sure to install threaded rod in crankshaft at least 1/2 in. (13 mm) to
prevent damage to threads.
b. Install plate, thrust bearing, washer and nut on rod.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-38 90-861329--1 MARCH 1999
c. Install torsional damper on crankshaft by turning nut until it contacts.
74529
a
a-Torsional Damper Remover and Installer (J-23523-E)
d. Remove tool from crankshaft.
e. To prevent oil leakage, apply Quicksilver RTV sealant to torsional damper keyway.
f. Install torsional damper bolt. Torque to 70 lb-ft (95 Nm).
4. Install drive pulley(s). Torque bolts to 35 lb-ft (48 Nm).
5. Install and adjust drive belts.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-39
Crankcase Oil Seal
Replacing Oil Seal Without Removing Front Cover
REMOVAL
1. Remove torsional damper.
2. Pry seal out of cover from the front with a large screwdriver. Be careful not to distort front
cover or damage crankshaft.
INSTALLATION
IMPORTANT: Correct rotation oil seal must be used to prevent oil leak.
1. Apply Quicksilver Perfect Seal to seal retainer mating surface and apply grease to seal
lips.
2. Install new seal with open end of seal inward, using crankcase front cover seal installer.
Drive seal in until it contacts. Do not use excessive force.
74531
a
b
a-Key In Crankshaft
b-Lobe of Bore Clears Key
3. Reinstall torsional damper as outlined.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-40 90-861329--1 MARCH 1999
Crankcase Front Cover
Removal
1. Remove engine from boat if necessary to gain access to cover.
2. Remove torsional damper and oil pan.
3. Remove water circulating pump.
4. Remove crankcase front cover.
5. If damaged, drive oil seal out of front cover (from the rear) using a punch.
Cleaning and Inspection
Clean front cover in solvent and dry with compressed air. Clean old gasket material and
sealer from mating surfaces on cover and cylinder block. Check gasket surface on front
cover for distortion, and fix if necessary. Surfaces must be clean and flat or oil leakage may
result.
Installation
1. Install oil seal in cover with lip of seal toward inside of engine, using crankcase front
cover seal installer. Support cover around seal area with appropriate tool as shown.
74530
a
a-Crankcase Front Cover Seal Installer (J-35468)
2. Coat both sides of front cover gasket with Quicksilver Perfect Seal and place in position
on engine.
3. Install front cover. Ensure holes in cover align with dowel pins in block. Torque front
cover attaching screws to 100 lb-in. (11 Nm).
4. Install oil pan and torsional damper as outlined.
5. Install water circulating pump.
6. Reinstall engine in boat.
7. Fill crankcase with engine oil.
CAUTION
Ensure that cooling water supply is available before starting the engine.
8. Start engine and check for water and oil leaks.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-41
Flywheel and Engine Coupler
Removal
1. Remove engine from boat. Refer to SECTION 2 Removal and Installation.
2. Refer to Flywheel Housing description in this section and remove flywheel housing and
related parts.
72318
b
c
a
a-Flywheel Housing
b-Cover
c-Press Mount Out with Press
3. Remove MCM coupler.
4. Remove flywheel.
72349
Alpha One Coupler
Inspection
1. Inspect splines in coupler for wear.
2. Check flywheel ring gear for worn and missing teeth.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-42 90-861329--1 MARCH 1999
Installation
1. Clean mating surfaces of flywheel and crankshaft. Remove any burrs. Mating surfaces
must be clean bare metal.
2. Align dowel hole in flywheel with dowel in crankshaft.
3. Install flywheel.
4. Torque bolts to 75lb-ft (100Nm).
5. Check flywheel runout as follows:
a. Attach a dial indicator to engine block.
b. Take readings around outer edge of flywheel. Push in on flywheel to remove crank-
shaft end play. Maximum runout - .008 in. (0.203 mm).
72353
a
b
a-.008 in. (0.203 mm) Maximum Runout
b-Push Flywheel And Crankshaft Forward As Far As It Will Go When Taking
Reading
6. Insert three rubber bumpers in Alpha coupler before installation on flywheel.
72354
a
a-Rubber Bumper
7. Install drive coupler. If reusing screws, use Loctite 27131.
8. Torque bolts to 35 lb-ft (48 Nm).
9. Install flywheel housing and related parts. Torque bolts to 30 lb-ft (41 Nm).
10. Install flywheel housing cover. Torque bolts to 80 lb-in. (9 Nm).
11. Refer to SECTION 2 Removal and Installation and install engine.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-43
Rear Main Oil Seal
The rear crankshaft oil seal can be replaced without removing the oil pan or rear main
bearing cap from engine.
Removal
1. Remove seal by using a screwdriver to pry it out of retainer as shown.
72355
c
a
b
a-Rear Seal
b-Seal Retainer
c-Slots (Three)
Cleaning and Inspection
1. Clean crankshaft/seal running surface and seal retainer.
2. Clean gasket material from mating surfaces.
3. Inspect oil seal retainer for cracks or scored surface.
4. Inspect oil seal for worn, dry or torn rubber. Replace if necessary (refer to Rear Main
Oil Seal as outlined).
5. Inspect alignment pin for damage; replace if necessary.
IMPORTANT: Correct rotation oil seal must be used to prevent oil leak.
Installation
1. Apply Quicksilver Perfect Seal to seal retainer mating surface. Apply grease to seal lips.
2. Install seal using rear main seal installer.
72356
a
a-Rear Main Seal Installer (J-26817-A)
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-44 90-861329--1 MARCH 1999
3. Coat seal lips with clean motor oil.
4. Install gasket and oil seal retainer with rear main seal.
5. Coat threads of oil seal retainer fasteners with Loctite Pipe Sealant with Teflon.
6. Install oil seal retainer fasteners and torque to 133 lb-in. (15 Nm).
7. Install oil pan fasteners. Torque 1/4-20 threaded fasteners to 80 lb-in. (9 Nm) and
5/16-18 threaded fasteners to 165 lb-in. (19 Nm).
NOTE: The oil pan gasket may be re-used if it is still pliable and is not cracked, torn or other-
wise damaged.
Main Bearings
IMPORTANT: Before removing main bearing caps or connecting rod caps, mark them
for reassembly in their original locations.
Main bearings are the precision insert type and do not use shims for adjustment. If
clearances are found to be excessive, a new bearing, both upper and lower halves, will be
required. Service bearings are available in standard size and .001 in., .010 in. and .020 in.
undersize.
Selective fitting of both rod and main bearing inserts is necessary in production in order to
obtain close tolerances. For this reason you may find one-half of a standard insert with one-
half of a .001 in. undersize insert which will decrease the clearance .0005 in. from using a
full standard bearing.
When a production crankshaft cannot be precision fitted by this method, it then is ground
.009 in. undersize on main journals only. A .009 in undersize bearing and .010 in. undersize
bearing may be used for precision fitting in same manner as previously described. Any
engine fitted with a .009 in. undersize crankshaft will be identified by the following markings:
“.009” will be stamped on crankshaft counterweight forward of center main journal.
No. “9” will be stamped on block at left front oil pan rail.
IMPORTANT: If crankshaft has an undersize journal and a new bearing is required,
journal must be reconditioned to accept a .010 or .020 in. undersize bearing as .009
in. undersize bearings are not available for service.
Inspection
In general, the lower half of the bearing (except No. 1 bearing) shows greater wear and more
distress from fatigue. If, upon inspection, the lower half is suitable for use, it can be assumed
that the upper half is also satisfactory. If the lower half shows evidence of wear or damage,
both upper and lower halves should be replaced. Never replace one half without replacing
the other half.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-45
Checking Clearances
To obtain accurate measurements while using Plastigage, or its equivalent, engine must be
out of the boat and upside down so crankshaft will rest on the upper bearings and total clear-
ance can be measured between lower bearing and journal.
To ensure the proper seating of the crankshaft, all bearing cap bolts should be at their speci-
fied torque. In addition, prior to checking fit of bearings, the surface of the crankshaft journal
and bearing should be wiped clean of oil.
1. With the oil pan and oil pump removed, remove bearing cap and wipe oil from journal
and bearing cap to be inspected.
2. Place a piece of gauging plastic the full width of the bearing (parallel to the crankshaft)
on the journal as shown.
72558
a
b
a-Gauging Plastic
b-Journal
3. Install the bearing cap and evenly torque the retaining bolts to specifications. Bearing
cap MUST be torqued to specification in order to ensure proper reading. Variations in
torque affect the compression of the plastic gauge.
IMPORTANT: Do not rotate the crankshaft while the gauging plastic is between the
bearing and journal.
4. Remove bearing cap. The flattened gauging plastic will be found adhering to either the
bearing cap or journal.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-46 90-861329--1 MARCH 1999
5. On the edge of the gauging plastic envelope there is a graduated scale which is corre-
lated in thousandths of an inch. Without removing the gauging plastic, measure its com-
pressed width (at the widest point) with the graduations on the gauging plastic envelope
as shown.
72358
a
b
a-Compressed Gauging Plastic
b-Graduated Scale
NOTE: Normally main bearing journals wear evenly and are not out of round. However, if
a bearing is being fitted to an out-of-round journal (.001 in. max.), be sure to fit to the
maximum diameter of the journal. If the bearing is fitted to the minimum diameter and the
journal is out of round .001 in., interference between the bearing and journal will result in
rapid bearing failure. If the flattened gauging plastic tapers toward the middle or ends, there
is a difference in clearance indicating taper, low spot or other irregularity of the bearing or
journal. Be sure to measure the journal with a micrometer if the flattened gauging plastic
indicates more than .001 in. difference.
6. If the bearing clearance is within specifications, the bearing insert is satisfactory. If the
clearance is not within specifications, replace the insert. Always replace both upper and
lower inserts as a unit.
7. A standard, or .001 in., undersize bearing may produce the proper clearance. If not, it
will be necessary to regrind the crankshaft journal for use with the next undersize
bearing.
8. After selecting new bearing, recheck clearance.
9. Proceed to the next bearing. After all bearings have been checked, rotate the crankshaft
to see that there is no excessive drag. When checking No. 1 main bearing, loosen acces-
sory drive belts so as to prevent tapered reading with plastic gauge.
Main Bearing Replacement
1. Remove and inspect crankshaft.
2. Remove main bearings from cylinder block and main bearing caps.
3. Coat bearing surfaces of new, correct-size, main bearing with oil and install in cylinder
block and main bearing caps. Check clearance.
4. Install crankshaft.
5. Torque all main bearing caps, EXCEPT THE REAR MAIN CAP, to 75 lb-ft (102 Nm).
6. Torque rear main bearing cap to 10-12 lb-ft (14-16 Nm); then tap end of crankshaft, first
rearward then forward with a lead hammer. This will line up rear main bearing and crank-
shaft thrust surfaces. Torque rear main bearing cap to 75 lb-ft (102 Nm).
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-47
Connecting Rod Bearings
Connecting rod bearings are of the precision insert type and do not use shims for adjust-
ment. DO NOT FILE RODS OR ROD CAPS. If clearances are found to be excessive, a new
bearing will be required. Service bearings are available in standard size and .001 in. and
.002 in. undersize for use with new and used standard size crankshafts, and in .010 in. and
.020 in. undersize for use with reconditioned crankshafts.
On removing a connecting rod cap, it is possible to find a .010 in. undersize bearing. These
are used in manufacturing for selective fitting.
Inspection and Replacement
IMPORTANT: Before you remove the connecting rod cap, mark the side of the rod and
cap with the cylinder number to assure matched reassembly of rod and cap.
1. Remove connecting rod cap and bearing.
2. Inspect bearing for evidence of wear or damage. Defective bearings should not be
installed. Typical bearing failures are shown under “General.”
3. Wipe bearings and crankshaft clean of oil.
4. Measure crankpin for out-of-round of taper with a micrometer. If not within specifica-
tions, replace or recondition crankshaft. If within specifications and new bearing is to be
installed, measure maximum diameter of crankpin to determine new bearing size
required.
5. If within specifications, measure new or used bearing clearances with gauging plastic.
IMPORTANT: If bearing is fitted to out-of-round crankpin, br sure to fit maximum
diameter of crankpin. If bearing is fitted to minimum diameter, and crankpin is
out-of-round .001 (0.02 mm), interference between bearing and crankpin will result
in rapid bearing failure.
a. Place a piece of gauging plastic the full width of crankpin (parallel to crankshaft).
b. Install bearing connecting rod and cap.
c. Place a piece of gauging plastic the length of the bearing (parallel to the crankshaft)
on the crankpin or bearing surface as shown. Position the gauging plastic in the
middle of the bearing shell. Bearings are eccentric and false readings could occur
if placed elsewhere.
72361
a
a-Gauging Plastic
d. Install the bearing in the connecting rod and cap.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-48 90-861329--1 MARCH 1999
e. Install the bearing cap and torque nuts to 45 lb-ft (61 Nm).
IMPORTANT: Do not turn the crankshaft with the gauging plastic installed.
f. Remove the bearing cap and using the scale on the gauging plastic envelope, mea-
sure the gauging plastic width at the widest point as shown.
72362
6. If the clearance exceeds specifications, select a new, correct size bearing and measure
the clearance.
Be sure to check what size bearing is being removed in order to determine proper replace-
ment size bearing. If clearance cannot be brought to within specifications, the crankpin will
have to be ground undersize. If the crankpin is already at maximum undersize, replace
crankshaft.
7. Coat the bearing surface with oil, install the rod cap and torque nuts to 45 lb-ft (61 Nm).
8. When all connecting rod bearings have been installed, tap each rod lightly (parallel to
the crankpin) to make sure they have clearance.
9. Measure all connecting rod side clearances between connecting rod caps as shown -
.006-.014 in. (0.16-0.35 mm).
72891
a
a-Take Measurement Here
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-49
Connecting Rod/Piston Assembly
Removal
1. With oil pan, oil pump and cylinder head removed, use a ridge reamer to remove any
ridge and/or deposits from upper end of cylinder bore.
IMPORTANT: Before ridge and/or deposits are removed, turn crankshaft until piston
is at bottom of stroke and place a cloth on top of piston to collect cuttings. After ridge
and/or deposits are removed, turn crankshaft until piston is at top of stroke, then
remove cloth and cuttings.
2. Inspect and mark connecting rods and bearing caps.
3. Remove connecting rod cap and install connecting rod bolt guide (3/8-24) on bolts. Push
connecting rod and piston assembly out of top of cylinder block.
NOTE: It will be necessary to turn crankshaft slightly to disconnect and remove some con-
necting rod and piston assemblies.
72892
a
a-Connecting Rod Bolt Guide (3/8-24) (J-5239)
Disassembly
1. Disassemble piston from connecting rod using piston pin remover as shown.
72365
a
b
d
c
e
a-Piston Pin Remover (J-24086-B)
b-Arched Base
c-Piston
d-Connecting Rod
e-Rod Support
2. Position connecting rod on tool rod support with rod support inserted between
connecting rod end and piston. Align piston pin with hole located in top of arched base.
3. Insert pin remover through hole (located in top of arched base) and into piston pin hole.
Press on pin remover to remove piston pin.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-50 90-861329--1 MARCH 1999
Cleaning and Inspection
CONNECTING RODS
1. Wash connecting rods in cleaning solvent and dry with compressed air.
2. Check for twisted and bent rods and inspect for nicks and cracks. Replace damaged
connecting rods.
PISTONS
NOTE: Cylinder bore and taper must be within specifications before pistons can be consid-
ered for reuse.
1. Clean varnish from piston skirts with a cleaning solvent. DO NOT WIRE BRUSH ANY
PART OF PISTON. Clean ring grooves with a groove cleaner and make sure oil ring
holes are clean.
2. Inspect piston for cracked ring lands, skirts and pin bosses, wavy worn ring lands,
scuffed or damaged skirts and eroded areas at top of piston. Replace pistons that are
damaged or show signs of excessive wear.
3. Inspect grooves for nicks and burrs that might cause rings to hang up.
4. Measure piston skirt (across centerline of piston pin) and check clearance as outlined
under “Cylinder Block.
5. Slip outer surface of a new top and second compression ring into respective piston ring
groove and roll ring entirely around the groove to ensure that ring is free as shown. If
binding occurs at any point, determine cause. If caused by ring groove, remove by dres-
sing with a fine cut file. If binding is caused by a distorted ring, recheck with another ring.
72894
6. Proper clearance of piston ring in its piston ring groove is very important to provide
proper ring action and reduce wear. When fitting new rings, clearances between ring
and groove surfaces should be measured. See “Specifications.”
72895
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-51
PISTON PINS
1. Piston pin clearance is designed to maintain adequate clearance under all engine
operating conditions. Because of this, piston and piston pin are a matched set and not
serviced separately.
2. Inspect piston pin bores and piston pins for wear. Piston pin bores and piston pins must
be free of varnish and scuffing when measured. Measure piston pin with a micrometer
and piston pin bore with a dial bore gauge or inside micrometer. If clearance is in excess
of the .001 in. (0.02 mm) wear limit, replace piston and piston pin assembly.
Reassembly
PISTONS AND PISTON PINS
IMPORTANT: When reassembling pistons and connecting rods, the following must
be kept in mind.
Piston and pin are machine fitted to each other and must remain together as a
matched set. Do not intermix pistons and pins.
If original pistons and/or connecting rods are being used, be sure to assemble
pistons and connecting rods so they can be reinstalled in same cylinder from
which they were removed.
Connecting rod bearing tangs are always toward outside of cylinder block.
72368
a
a-Rod Bearing Tangs
Notch on piston must be positioned toward the front of the engine.
72896
a
a-Notch
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-52 90-861329--1 MARCH 1999
1. Assemble piston to connecting rod using piston pin remover as shown. Follow instruc-
tions supplied with tool.
72371
a
a-Piston Pin Remover (J-24086-B)
2. Once assembled, check piston for freedom of movement (back and forth and up and
down) on connecting rod. Piston should move freely in all directions. If it does not, piston
pin bore is tight and piston/pin assembly must be replaced.
3. If a new connecting rod has been installed, mark connecting rod and cap (on side of rod
and cap with slots for connecting rod bearing tangs) with cylinder number in which it will
be installed.
PISTON RINGS
All compression rings are marked on upper side of ring. When installing compression rings,
make sure that marked side is toward top of piston. The top ring is treated with molybdenum
for maximum life. Oil control rings are a three piece type, consisting of 2 segments (rails)
and a spacer.
Oil control rings are a three-piece type, consisting of two rings and a spacer.
1. Select rings comparable in size to cylinder bore and piston size.
2. Slip compression ring in cylinder bore, then press ring down into cylinder bore about 1/4
in. (6 mm) (below ring travel). Be sure that ring is square with cylinder wall.
3. Measure gap between ends of ring with a feeler gauge as shown.
72372
4. If gap between ends of ring is below specifications, remove ring and try another for fit.
5. Fit each compression ring to cylinder in which it is going to be used.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-53
6. Clean and inspect pistons, if not previously done.
7. Install piston rings as follows:
a. Install oil ring spacer in groove and insert anti- rotation tang in oil hole.
b. Hold spacer ends butted and install lower steel oil ring rail with gap properly located.
c. Install upper steel oil ring rail with gap properly located.
d. Flex the oil ring assembly to make sure ring is free. If binding occurs at any point,
the cause should be determined and, if caused by ring groove, removed by dressing
groove with a fine cut file. If binding is caused by a distorted ring, use a new ring.
IMPORTANT: Use piston ring expander (91-24697) for compression ring installation.
e. Install lower compression ring with marked side up, using ring expander.
f. Install top compression ring with marked side up, using ring expander.
Installation
IMPORTANT: Cylinder bores must be clean before piston installation. Clean with a
light honing, as necessary. Then clean with hot water and detergent wash. After
cleaning, swab bores several times with light engine oil and clean cloth, then wipe
with a clean dry cloth.
1. Lubricate connecting rod bearings and install in rods and rod caps.
2. Lightly coat pistons, rings and cylinder walls with light engine oil.
3. With bearing caps removed, install connecting rod bolt guide (3/8-24) (J-5239) on
connecting rod bolts.
IMPORTANT: Be sure ring gaps are properly positioned as shown.
72373
a
b
b
c
d
e
f
g
Ring Gap Location
a-Oil Ring Spacer Gap (Tang In Hole Or Slot Within Arc)
b-Oil Ring Gaps
c-2nd Compression Ring Gap
d-Top Compression Ring Gap
e-Port Side
f-Engine Front
g-Starboard Side
4. Install each connecting rod and piston assembly in its respective bore.
a. Install with connecting rod bearing tangs toward outside of cylinder block.
b. Use piston ring compressor to compress rings.
c. Guide connecting rod into place on crankshaft journal with connecting rod bolt guide.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-54 90-861329--1 MARCH 1999
d. Use a hammer handle with light blows to install piston into bore.
e. Hold ring compressor firmly against cylinder block until all piston rings have entered
cylinder bore.
IMPORTANT: Be sure to install new pistons in same cylinders for which they were
fitted, and used pistons in same cylinder from which they were removed. Each
connecting rod and bearing cap should be marked, beginning at front of engine.
Numbers on connecting rod and bearing cap must be on same side when installed
in cylinder bore. If a connecting rod is ever transposed from one block or cylinder to
another, new bearings should be fitted and connecting rod should be numbered to
correspond with new cylinder number.
72898
a
a-Piston Ring Compressor (J-8037)
5. Remove connecting rod bolt guide.
6. Install bearing caps and torque nuts to 45 lb-ft (27 Nm).
7. Check connecting rod side clearance as previously described.
NOTE: If bearing replacement is required, refer to Connecting Rod Bearings.
8. Install as previously outlined:
a. Oil pump.
b. Dipstick and oil pan.
c. Cylinder heads.
d. Intake manifold.
e. Distributor.
9. Torque rocker arm nuts to 20 lb-ft (27 Nm).
10. Install rocker arm cover and torque to 40 lb-in (4.5 Nm)
11. Fill crankcase with oil. Refer to SECTION 1B “Maintenance.”
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-55
Crankshaft
Removal
1. Remove engine from boat.
2. Drain crankcase oil.
3. Remove as outlined:
a. Starter.
b. Flywheel housing.
c. Drive coupler and flywheel.
d. Belts.
e. Water pump.
f. Crankshaft pulley and torsional damper.
g. Spark plugs.
h. Oil pan and dipstick tube.
i. Oil pump.
j. Timing chain cover.
4. Turn crankshaft to align timing mark with camshaft mark.
5. Remove camshaft sprocket.
6. Remove rear main seal and retainer.
7. Ensure all bearing caps (main and connecting rods) are marked so they can be rein-
stalled in their original locations.
8. Remove connecting rod bearing caps, then push piston and rod assemblies toward
heads.
9. Remove main bearing caps and carefully lift crankshaft out of cylinder block.
10. Remove crankshaft gear as shown.
74476
11. If new main and/or connecting rod bearings are to be installed, remove main bearing
inserts from cylinder block and bearing caps, and/or connecting rod bearing inserts from
connecting rod and caps. Install new bearings following procedures outlined.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-56 90-861329--1 MARCH 1999
Cleaning and Inspection
1. Wash crankshaft in solvent and dry with compressed air.
2. Measure main bearing journals and crankpin dimensions with a micrometer for
out-of-round, taper or undersize (see “Specifications”).
3. Check crankshaft for runout (by supporting at front and rear main bearings journals in
V-blocks) and check at front and rear intermediate journals with a dial indicator (see
“Specifications”).
4. Replace or recondition crankshaft if not within specifications.
Installation
1. If a new crankshaft is being installed, remove timing sprocket from old crankshaft and
reinstall on new crankshaft as outlined.
IMPORTANT: Be sure that all bearings and crankshaft journals are clean.
2. Install main bearings in engine block as shown.
72359
a
b
c
Main Bearing Inserts
a-Lower Bearing Insert
b-Upper Bearing Insert
c-Oil Groove
3. Carefully lower crankshaft into place. Be careful not to damage bearing surface.
4. Check clearance of each main bearing, following procedure outlined under Main Bear-
ings.” If bearing clearances are satisfactory, apply engine oil to journals and bearings.
5. Install main bearing caps. Torque bolts to 75 lb-ft (102 Nm). When tightening rear main
bearing cap, follow procedure outlined under Main Bearings.
6. Check crankshaft end play as previously outlined.
7. Install rear main seal retainer and seal. Torque fasteners to 133 lb-in. (15 Nm).
8. Check clearance for each connecting rod bearing, following procedure under Connect-
ing Rod Bearings. If bearing clearances are satisfactory, apply engine oil to journals and
bearings.
9. Install rod caps and torque nuts to 45 lb-ft (61 Nm).
10. Turn crankshaft so mark on timing sprocket is facing camshaft.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-57
11. Install as outlined:
a. Timing chain and sprocket on camshaft - align marks with crankshaft.
b. Timing chain cover.
c. Oil pump.
d. Dipstick tube and oil pan.
e. Spark plugs.
f. Torsional damper and crankshaft pulley.
g. Water pump.
h. Belts.
i. Flywheel and drive coupler.
j. Flywheel housing.
k. Starter.
12. Install new oil filter. Fill crankcase with oil.
Crankshaft Sprocket
Removal
1. Remove torsional damper and crankcase front cover as previously outlined.
2. Remove camshaft timing chain as outlined, and using crankshaft gear and sprocket
puller (J-5825-A), remove crankshaft sprocket.
Installation
1. Using crankshaft gear and sprocket installer, as shown, install sprocket on crankshaft.
72377
a
a-Crankshaft Gear and Sprocket Installer (J-5590)
2. Install timing chain as outlined.
3. Install crankcase cover and torsional damper as outlined.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-58 90-861329--1 MARCH 1999
Camshaft
Measuring Lobe Lift
NOTE: Procedure is similar to checking valve timing. If improper valve operation is indi-
cated, measure lift of each push rod in consecutive order and record readings.
1. Remove valve mechanism as previously outlined.
2. Position indicator with ball socket adaptor tool on push rod. Be sure that push rod is in
lifter socket.
72907
a
a-Ball Socket Adaptor Tool (J-8520-1)
3. Rotate crankshaft torsional damper slowly in direction of rotation until lifter is on heel of
cam lobe. At this point, push rod will be in its lowest position.
4. Set dial indicator on zero, then rotate balancer slowly (or attach an auxiliary starter
switch and “bump” engine over) until push rod is in fully raised position.
5. Compare total lift, recorded from dial indicator, with “Specifications.”
6. Continue to rotate engine until indicator reads zero. This will be a check on accuracy of
original indicator reading.
7. If camshaft readings for all lobes are within specifications, remove dial indicator assem-
bly.
8. Install rocker arm and push rod. Torque nuts to 20 lb-ft (27 Nm).
Removal
1. Remove valve lifters as previously outlined.
2. Remove crankcase front cover as previously outlined.
3. Remove fuel pump.
4. Align timing gear marks, then remove the two camshaft thrust plate screws by working
through holes in camshaft gear.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-59
5. Pull camshaft and gear assembly out through front of block.
IMPORTANT: Support camshaft carefully when removing to protect camshaft bear-
ings.
74438
a
b
a-Timing Marks
b-Screw Access Holes
Inspection
1. Measure camshaft bearing journals with a micrometer for out-of-round condition. If
journals exceed .001 in. (0.02 mm) out-of-round, camshaft should be replaced.
2. Also check camshaft for alignment with V-blocks and dial indicator which indicates exact
amount camshaft is out of true. If dial indicator reads more than .002 in. (0.05 mm)
camshaft should be replaced.
72909
Checking Camshaft Alignment
3. Inspect camshaft gear and thrust plate for wear or damage. Measure camshaft end play
.001 - .005 in. (0.03-0.1 mm).
74439
d
a
b
c
a-Feeler Gauge
b-Camshaft Gear
c-Camshaft Thrust Plate
d-Take Measurement Here
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-60 90-861329--1 MARCH 1999
Camshaft Gear Replacement
1. If inspection indicates that camshaft, gear or thrust plate should be replaced, remove
gear from camshaft.
2. Place camshaft through gear remover, place end of remover on table of a press shaft
out of gear.
CAUTION
Position thrust plate so that woodruff key in shaft does not damage plate when shaft
is pressed out of gear. Also support hub of gear, or gear will be seriously damaged.
74477
b
a
c
a-Camshaft Gear
b-Support Sleeve
c-Camshaft
Installation
1. Install camshaft and gear assembly in engine block. Be careful not to damage camshaft
bearings or camshaft.
74438
a
b
a-Timing Marks
b-Screw Access Holes
2. Turn crankshaft and camshaft so the timing marks on gear teeth will line up. Push
camshaft thrust plate to block screws and torque to specifications.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-61
3. Check camshaft and crankshaft gear run-out with a dial indicator. Camshaft gear run-out
should not exceed .004 in. (0.1 mm) and crankshaft gear run-out should not exceed .003
in. (0.07 mm).
74440
Checking Timing Gear Run-Out
4. If gear run-out is excessive, remove gear and clean burrs from shaft or replace gear.
5. Check backlash between timing gear teeth with a dial indicator. Backlash should not be
less than .004 in. (0.010 mm) or more than .006 in. (0.15 mm).
74441
Checking Timing Gear Backlash
6. Install fuel pump.
7. Install front crankcase cover.
8. Pour GM engine oil supplement or light engine oil over camshaft lobes and install valve
lifters.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-62 90-861329--1 MARCH 1999
Camshaft Bearings
Removal
Camshaft bearings can be replaced while engine is disassembled for overhaul or without
complete disassembly. To replace bearings without complete disassembly, remove cam-
shaft and crankshaft, leaving cylinder heads attached and pistons in place. Before removing
crankshaft, fasten connecting rods against sides of engine so that they will not interfere
while replacing camshaft bearings.
1. With camshaft and crankshaft removed, drive camshaft rear plug from cylinder block.
NOTE: This procedure is based on removal of bearings from center of engine first, thus
requiring a minimum amount of turns to remove all bearings.
2. Using camshaft bearing remover and installer set (J-6098-01) (with nut and thrust
washer installed to end of threads), position pilot in front camshaft bearing and install
puller screw through pilot.
3. Install tool with shoulder toward bearing. Be sure a sufficient amount of threads are
engaged.
4. Using two wrenches, hold puller screw while turning nut. When bearing has been pulled
from bore, remove tool and bearing from puller screw.
74478
5. Remove remaining bearings (except front and rear) in same manner. It will be necessary
to position pilot in rear camshaft bearing to remove rear intermediate bearing.
74479
6. Assemble driver on driver handle and remove front and rear camshaft bearings by
driving toward center of cylinder block.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-63
Inspection
Clean camshaft bearing bores in cylinder block with solvent and blow out with compressed
air. Be sure grooves and drilled oil passages are clean.
Installation
CAUTION
Oil holes in bearings must line up with oil holes in cylinder block. Oil hole is on top
side of bearing shell and cannot be seen during installation, so first align bearing
shell oil hole with oil hole in bore and mark opposite side of bearing and block at
bore to easily position oil hole during installation.
IMPORTANT: Front bearing must be driven approximately .125 in. (3 mm) behind the
block face to uncover oil hole to timing gear oil nozzle.
IMPORTANT: All camshaft bearings are not the same. Be sure to install bearings in
proper locations (Indicated by bearing manufacturer) and to position bearings as
follows (directional references are in reference to engine in its normal operating
position):
Lubricate outer surface of new camshaft bearings with engine oil to ease installation.
1. Installing intermediate and center bearings:
a. Install nut and thrust washer all the way onto puller screw, then position pilot in front
camshaft bearing bore and insert screw through pilot.
b. Index center camshaft bearing, then position appropriate size remover and installer
tool in bearing and thread puller screw into tool. Be sure at least 1/2 in. (13 mm) of
threads are engaged.
74478
Pulling Cam Bearing From Bore
c. Using two wrenches, hold puller screw and turn nut until bearing has been pulled into
position. Remove the remover and installer tool and ensure that oil hole(s) in bearing
is positioned correctly.
d. Install intermediate bearings in same manner. Be sure to index bearings correctly.
It will be necessary to position pilot in rear camshaft bearing bore to install rear inter-
mediate bearing.
2. Installing front and rear bearings:
a. Install appropriate size remover and installer tool on drive handle.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-64 90-861329--1 MARCH 1999
b. Index front bearing (as explained in Important above), and drive it into position with
tool. Check position of oil hole(s) in bearing to ensure bearing is positioned correctly.
74479
Removal And Installation Camshaft Bearings
a-Installation Tool
b-Camshaft Bearing
c. Install rear bearing in same manner. Be sure to index bearing correctly.
3. Install a new camshaft rear plug.
IMPORTANT: Plug must be installed flush to 1/32 in. (0.8 mm) deep and must be paral-
lel with rear surface of cylinder block.
4. Install crankshaft and camshaft as previously outlined.
Cylinder Block
Cleaning and Inspection
1. Remove all engine components as previously outlined.
2. Wash cylinder block thoroughly in cleaning solvent and clean all gasket surfaces.
3. Remove oil gallery plugs and clean all oil passages.
4. Remove expansion plugs.
NOTE: These plugs may be removed with a sharp punch or they may be drilled and pried
out.
5. Clean and inspect water passages in cylinder block.
6. Inspect cylinder block for cracks in cylinder walls, water jacket valve lifter bores and main
bearing webs.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-65
7. Measure cylinder bores to ensure they meet specifications.
CAUTION
Measure cylinder walls for taper, out-of-round or excessive ridge at top of ring
travel. This should be done with a dial indicator or inside micrometer. Carefully
work gauge up and down cylinder to determine taper and turn it to different points
around cylinder wall to determine out-of-round condition. If cylinders exceed
specifications, boring and/or honing will be necessary.
72385
a
b
a
b
Cylinder Measurement
a-At right angle to centerline of engine
b-Parallel to centerline of engine
“Out-of-Round” = Difference between “A” and “B”
“Taper” =Difference between measurement “A” at top of cylinder bore and “A” measurement
at bottom of cylinder bore
72386
Measuring Cylinder Bore With Snap Gauge
72387
Measuring Cylinder Bore With Dial Indicator
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-66 90-861329--1 MARCH 1999
8. Check cylinder head gasket surfaces for warp with a machinists straight-edge and a
feeler gauge, as shown. Take measurements diagonally across surfaces (both ways)
and straight down center. If surfaces are warped more than .003 in. (0.07 mm) in a 6 in.
area or .007 in. (0.2 mm) overall, block must be resurfaced by an automotive machine
shop.
72910
a
b
a-Machinist’s Straight-Edge
b-Feeler Gauge
CYLINDER CONDITIONING
1. Performance of the following operation depends upon engine condition at time of repair.
2. If cylinder block inspection indicates that block is suitable for continued use (except for
out-of-round or tapered cylinders), they can be conditioned by honing or boring.
3. If cylinders have less than .005 in. (0.127 mm) taper or wear, they can be conditioned
with a hone and fitted with high limit standard size piston. A cylinder bore of more than
.005 in. wear or taper may not clean up entirely when fitted to a high limit piston. To
entirely clean up the bore, it will be necessary to bore for an oversize piston. If more than
.005 in. taper or wear, bore and hone to smallest oversize that will permit complete
resurfacing of all cylinders.
4. When pistons are being fitted and honing is not necessary, cylinder bores may be
cleaned with a hot water and detergent wash. After cleaning, swab cylinder bores
several times with light engine oil and a clean cloth, then wipe with a clean dry cloth.
CYLINDER BORING
1. Before using any type boring bar, file off top of cylinder block to remove dirt or burrs. This
is very important to prevent boring bar tilt, resulting in the bored cylinder wall not being
at right angles to crankshaft.
2. Measure piston to be fitted with a micrometer, measuring at center of piston skirt and
at right angles to piston pin. Bore cylinder to same diameter as piston and hone to give
specified clearance.
NOTE: Hone cylinders as outlined under Cylinder Honing and Piston Selection,
following.
3. Carefully observe instructions furnished by manufacturer of equipment being used.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-67
CYLINDER HONING
1. Follow hone manufacturers recommendations for use of hone and cleaning and lubrica-
tion during honing.
2. Occasionally, during the honing operation, thoroughly clean cylinder bore and check
piston for correct fit in cylinder.
3. When finish-honing a cylinder bore to fit a piston, move hone up and down at a sufficient
speed to obtain very fine uniform surface finish marks in a crosshatch pattern of approxi-
mately 30 degrees to cylinder bore. Finish marks should be clean but not sharp, free
from imbedded particles and torn or folded metal.
4. Permanently mark piston (for cylinder to which it has been fitted) and proceed to hone
cylinders and fit remaining pistons.
IMPORTANT: Handle pistons with care and do not attempt to force them through cyl-
inder until cylinder is honed to correct size, as this type piston can be distorted by
careless handling.
5. Thoroughly clean cylinder bores with hot water and detergent. Scrub well with a stiff
bristle brush and rinse thoroughly with hot water. It is extremely essential that a good
cleaning operation be performed. If any abrasive material remains in cylinder bores, it
will rapidly wear new rings and cylinder bores in addition to bearings lubricated by the
contaminated oil. Swab bores several times with light engine oil on a clean cloth, then
wipe with a clean dry cloth. Cylinder should not be cleaned with kerosene or gasoline.
Clean remainder of cylinder block to remove excess material spread during honing
operation.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-68 90-861329--1 MARCH 1999
PISTON SELECTION
1. Check used piston to cylinder bore clearance as follows:
a. Measure cylinder bore diameter with a snap gauge 2-1/2 in. (64 mm) from top of cyl-
inder bore as follows.
72386
b. Measure piston diameter at skirt across center line of piston pin as shown.
72911
c. Subtract piston diameter from cylinder bore diameter to determine piston-to-bore
clearance.
d. Determine if piston-to-bore clearance is in acceptable range shown in “Specifica-
tions.”
2. If used piston is not satisfactory, determine if a new piston can be selected to fit cylinder
bore within acceptable range.
3. If cylinder bore must be reconditioned, measure new piston diameter (across centerline
of piston pin), then hone cylinder bore to correct clearance (preferable range).
4. Mark piston to identify cylinder for which it was fitted.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-69
Oil Filter By-Pass Valve
Inspection and/or Replacement
With oil filter removed, check spring and fiber valve for operation. Inspect for a cracked or
broken valve. If replacement is necessary, pry valve out with screwdriver. Install and seat
a new valve by tapping in place with a 9/16 in. thin wall deep socket.
Refer to Engine Parts List when ordering parts for oil filter by-pass valve.
1. Remove oil filter from cylinder block and remove by-pass valve.
2. Clean by-pass valve in solvent and blow dry with compressed air.
3. Inspect fiber valve for cracks or other damage. Check that valve fits tightly against its
seat. Push valve down and release it. Valve should return freely to its seat. If valve
operation is questionable, by-pass valve should be replaced.
72912
a
Typical By-Pass Valve
a-Fiber Valve (Ensure Valve Fits Tightly Against the Seal)
4. Wipe out valve chamber in cylinder block to remove any foreign material.
5. Install by-pass valve or cylinder block adaptor to engine block.
6. Lubricate oil filter rubber seal and install hand-tight only.
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-70 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-71
THIS PAGE IS INTENTIONALLY BLANK
Index
181 CID (3.0L) 4 CYLINDER GM ENGINE SERVICE MANUAL NUMBER 26
Page 3A-72 90-861329--1 MARCH 1999
THIS PAGE IS INTENTIONALLY BLANK
Index
4
A
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-1
ELECTRICAL SYSTEM
Section 4A - Starting System
Table of Contents
Identification 4A-2. . . . . . . . . . . . . . . . . . . . . . . . . .
Replacement Parts Warning 4A-2. . . . . . . . . . . .
Battery 4A-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery Cable Recommendations 4A-3. . . . .
Starting System Components 4A-4. . . . . . . . . . .
Replacement Parts Warning 4A-5. . . . . . . . . . . .
Maintenance 4A-5. . . . . . . . . . . . . . . . . . . . . . .
Storage 4A-6. . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing 4A-7. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Positive Current Flow 4A-8. . . . . . . . . . . . . . . . . .
Charging Guide 4A-9. . . . . . . . . . . . . . . . . . . . . . .
12 Volt Battery Recommended Rate*
and Time for Fully Discharged
Condition 4A-9. . . . . . . . . . . . . . . . . . . . . . . . .
Slave Solenoid Identification 4A-10. . . . . . . . . . .
Types 4A-10. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard Type Slave Solenoid 4A-10. . . . . .
Switch Type Slave Solenoid 4A-10. . . . . . . . .
Testing/Replacement 4A-11. . . . . . . . . . . . . . .
Solenoid Switch 4A-11. . . . . . . . . . . . . . . . . . . . . .
Periodic Inspection 4A-11. . . . . . . . . . . . . . . . . . .
PG260 Starter Motor 4A-12. . . . . . . . . . . . . . . . . .
PG260 Specifications 4A-12. . . . . . . . . . . . . .
Torque Specification 4A-12. . . . . . . . . . . . . . .
Description 4A-12. . . . . . . . . . . . . . . . . . . . . . .
PG260 Exploded View 4A-13. . . . . . . . . . . . .
Starter Motor Repair 4A-14. . . . . . . . . . . . . . . . . .
Removal 4A-14. . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4A-14. . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4A-18. . . . . . . . . . . .
Armature Tests 4A-19. . . . . . . . . . . . . . . . . . . .
Armature Bearing (Commutator End) 4A-20.
Gear Bearing 4A-20. . . . . . . . . . . . . . . . . . . . .
Shaft Assembly Bearing 4A-21. . . . . . . . . . . .
Drive End Housing Bearing 4A-21. . . . . . . . .
Brushes and Brush Holder 4A-22. . . . . . . . . .
Reassembly 4A-24. . . . . . . . . . . . . . . . . . . . . .
Starter Solenoid 4A-28. . . . . . . . . . . . . . . . . . . . . .
Testing/Replacement 4A-28. . . . . . . . . . . . . . .
Installation 4A-30. . . . . . . . . . . . . . . . . . . . . . . .
PG260F1 Starter Motor 4A-31. . . . . . . . . . . . . . .
PG260F1 Specifications 4A-31. . . . . . . . . . . .
Torque Specifications 4A-31. . . . . . . . . . . . . .
Lubricants/Sealants 4A-31. . . . . . . . . . . . . . . .
Description 4A-31. . . . . . . . . . . . . . . . . . . . . . .
Exploded View 4A-32. . . . . . . . . . . . . . . . . . . .
Starter Motor Repair 4A-33. . . . . . . . . . . . . . . . . .
Removal 4A-33. . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4A-33. . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4A-37. . . . . . . . . . . .
Armature Tests 4A-37. . . . . . . . . . . . . . . . . . . .
Reassembly 4A-38. . . . . . . . . . . . . . . . . . . . . .
Starter Solenoid 4A-42. . . . . . . . . . . . . . . . . . .
Installation 4A-44. . . . . . . . . . . . . . . . . . . . . . . .
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-2 90-861329--1 MARCH 1999
Identification
The starter identification number is located as shown.
72059
a
Delco PG 260 Starter Motor
a-Starter Identification Number
75820
Delco PG260F1 Starter Motor
NOTE: The RP long block, S/N 0L097000 and above, has 3 starter motor mounting holes
in the cylinder block. The RK long block, S/N 0L096999 and below, has 2 starter motor
mounting holes in the cylinder block.
Replacement Parts Warning
WARNING
Electrical, ignition and fuel system components on your MerCruiser are designed
and manufactured to comply with U.S. Coast Guard Rules and Regulations to
minimize risks of fire and explosion.
WARNING
Use of replacement electrical, ignition or fuel system components, which do not
comply with these rules and regulations, could result in a fire or explosion hazard
and should be avoided.
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-3
Battery
Battery Cold Cranking Amperage
3.0L 375 cca, 475 mca, 90Ah
Battery Cable Recommendations
IMPORTANT: Terminals must be soldered to cable ends to ensure good electrical
contact. Use electrical grade (resin flux) solder only. Do not use acid flux solder, as
it may cause corrosion and failure.
Cable Length
Cable Gauge
Up to 3-1/2 ft (1.1 m) 4 (25 mm
2
)
3-1/2 - 6 ft (1.1-1.8 m) 2 (35 mm
2
)
6 - 7-1/2 ft (1.8-2.3 m) 1 (50 mm
2
)
7-1/2 - 9-1/2 ft (2.3-2.9 m) 0 (50 mm
2
)
9-1/2 - 12 ft (2.9-3.7 m) 00 (70 mm
2
)
12 - 15 ft (3.7-4.6 m) 000 (95 mm
2
)
15 - 19 ft (4.6-5.8 m) 0000 (120 mm
2
)
Both positive (+) and negative (–) cables
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-4 90-861329--1 MARCH 1999
Starting System Components
72929
I
B
CA
a
h
b
e
c
d
f
g
a-Ignition Switch
b-Neutral Safety Switch
c-Starter Slave Solenoid
d-Circuit Breaker (not on all models)
e-Engine Ground Stud
f-Starter Solenoid
g-Wire Junction
h-20 Amp Fuse
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-5
Replacement Parts Warning
WARNING
Electrical, ignition and fuel system components on your MerCruiser are designed
and manufactured to comply with U.S. Coast Guard Rules and Regulations to mini-
mize risks of fire and explosion.
Use of replacement electrical, ignition or fuel system components that do not comply with
these rules and regulations could result in a fire or explosion hazard and should be avoided.
Maintenance
WARNING
Do not use jumper cables and a booster battery to start engine. Do not recharge a
weak battery in the boat. Remove battery and recharge in a ventilated area away
from fuel vapors, sparks or flames.
WARNING
Batteries contain acid which can cause severe burns. Avoid contact with skin, eyes
and clothing. Batteries also produce hydrogen and oxygen gases when being
charged. This explosive gas escapes fill/vent cell caps and may form an explosive
atmosphere around the battery for several hours after it has been charged; sparks
or flames can ignite the gas and cause an explosion that may shatter the battery and
could cause blindness or other serious injury.
Safety glasses and rubber gloves are recommended when handling batteries or
filling with electrolyte. Hydrogen gases that escape from the battery during
charging are explosive. When charging batteries, be sure battery compartment, or
area where battery is located, is well vented. Battery electrolyte is a corrosive acid
and should be handled with care. If electrolyte is spilled or splashed on any part of
the body, immediately flush the exposed area with liberal amounts of water and
obtain medical aid as soon as possible.
CAUTION
To prevent damage to the electrical system be sure to adhere to the following:
When installing battery, be sure to connect the POSITIVE (+) battery cable to
POSITIVE (+) battery terminal first and then the NEGATIVE (–) battery cable to
NEGATIVE (–) battery terminal.
Never disconnect the battery cables while the engine is running.
If a charger or booster is to be used, be sure to connect it in parallel with existing
battery (positive to positive and negative to negative).
When applying a booster charge to battery, disconnect both cables from battery
(to prevent damage to voltage regulator).
Check battery condition periodically.
Make sure that battery leads are kept clean and tight.
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-6 90-861329--1 MARCH 1999
1. Ensure that the battery meets the following certain conditions before testing:
CAUTION
Test battery in well ventilated area as gases given off by battery are hazardous.
Battery must be 60 to 100°F (16 to 38°C).
Electrolyte level must be correct in all cells.
Battery must be at least half charged.
No obvious defects.
2. Place battery under heavy load (as during engine cranking or with a variable resistor
tester) and test cell voltage while under load:
a. Check voltage per manufacturers specifications.
b. If readings are low, recharge and retest.
c. If readings remain low, battery should be replaced.
Storage
1. Remove battery and clean exterior.
2. Check fluid level and fill if low.
3. Cover terminals and bolts with light coat of grease.
4. Set battery on wood or in carton; store in cool, dry place.
5. Check every 20 days for fluid level and slow charge.
IMPORTANT: A discharged battery can be damaged by freezing.
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-7
Testing
A strong battery must be maintained. If battery shows less than 9-1/2 volts when under start-
ing load, (at 80° F or 27° C) it should be recharged. Check with DC voltmeter.
74307
10
0
5
15
10
5
15
b
a
a-Voltmeter
b-Battery
Place battery under heavy load (as during engine cranking or with a variable resistor tester)
and test cell voltage while under load.
Certain conditions must be met before testing.
Battery must be 60 to 100°F (16 to 38°C).
Electrolyte level must be correct in all cells.
Battery must be at least half charged.
No obvious defects.
1. Check voltage per manufacturers specifications.
2. If readings are low, recharge and retest.
3. If readings remain low, battery should be replaced.
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-8 90-861329--1 MARCH 1999
Positive Current Flow
This is a general description of the positive current flow, from the battery and through the
system until the starter motor cranks.
Battery to the solenoid switch (on starter) (RED battery cable).
Solenoid switch to circuit breaker (RED).
Circuit breaker to wire junction (RED-PUR).
Wire junction to wiring harness plug (RED-PUR) terminal 6.
Wiring harness plug to 20 amp fuse (RED-PUR).
20 amp fuse to ignition switch terminal I (RED-PUR). At this point ignition switch is turned
to START.
Ignition switch terminal I to terminal C.
Ignition switch terminal C to neutral start switch (YEL-RED). NEUTRAL START
SWITCH MUST BE AT NEUTRAL POSITION.
Neutral start switch to wiring harness plug terminal 7 (YEL-RED).
Wiring harness plug to starter solenoid (small terminal) (YEL-RED). Also ensure that
black (small terminal) wire is grounded.
Starter solenoid is now closed, completing circuit between large terminal (RED-PUR)
and other large terminal (YEL-RED), causing starter motor to crank.
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-9
Charging Guide
12 Volt Battery Recommended Rate* and Time for Fully Discharged Condition
Twenty Hour
Rating
5
Amperes
10
Amperes
20
Amperes
30
Amperes
40
Amperes
50
Amperes
50
Ampere-Hours or
less
10 Hours 5 Hours
2-1/2
Hours
2 Hours
Above 50 to 75
Ampere-Hours
15 Hours
7-1/2
Hours
3-1/2
Hours
2-1/2
Hours
2 Hours
1-1/2
Hours
Above 75 to 100
Ampere-Hours
20 Hours 10 Hours 5 Hours 3 Hours
2-1/2
Hours
2 Hours
Above 100 to
150
Ampere-Hours
30 Hours 15 Hours
7-1/2
Hours
5 Hours
3-1/2
Hours
3 Hours
Above 150
Ampere-Hours
20 Hours 10 Hours
6-1/2
Hours
5 Hours 4 Hours
* Initial rate for constant voltage taper rate charger
To avoid damage, charging rate must be reduced or temporarily halted, if:
1. Electrolyte temperature exceeds 125° F (52° C).
2. Violent gassing or spewing of electrolyte occurs.
Battery is fully charged when, over a two hour period at a low charging rate in amperes, all
cells are gassing freely and no change in specific gravity occurs. For the most satisfactory
charging, the lower charging rates in amperes are recommended.
Full charge specific gravity is 1.260-1.280, corrected for temperature with electrolyte level
at split ring.
Battery Power as Affected by Temperature
74310
100%
83%
61%
45%
80°F
(27°C)
32°F (0°C)
0°F
(-18°C)
-20°F
(-29°C)
100%
165%
250%
350%
Power (Watts) Available Power (Watts) Required
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-10 90-861329--1 MARCH 1999
Slave Solenoid Identification
Types
There are two types of slave solenoids (standard or switch) used on MerCruiser engines.
These engines use a standard type solenoid; do not substitute a switch type solenoid.
The other engines use a slave solenoid to energize the starter motor solenoid. Some model
engines use the small terminal on the switch type solenoid for ignition by-pass during the
starting of the engine. Because of this, be sure to use correct type of slave solenoid for re-
placement.
Standard Type Slave Solenoid
a
b
c
d
e
a
c
b
74581
Starting Position Off Or Run Position
a-From Key Switch (12 Volts In Start Position)
b-To Ground
c-12 Volts From Battery
d-0 Volts From Starter
e-12 Volts To Starter
Switch Type Slave Solenoid
74582
b
a
c
d
e
f
g
b
a
c
Starting Position Off Or Run Position
a-From Key Switch (12 Volts in Start Position)
b-Mounting Bracket and Ground
c-12 Volts from Battery
d-0 Volts To Starter
e-0 Volts To Ignition Coil
f-12 Volts To Starter
g-12 Volts To Ignition Coil
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-11
Testing/Replacement
1. Using continuity meter, connect test leads as shown and connect 12-volt battery with
jumper leads as shown.
72630
2. If no meter movement is present, replace solenoid.
Solenoid Switch
The solenoid switch, along with plunger, return spring, and shift lever, are completely sealed
and permanently mount-ed in the drive housing. If solenoid is defective, entire drive housing
must be replaced.
Periodic Inspection
Cranking motor and solenoid are completely enclosed in the drive housing to prevent
entrance of moisture and dirt. However, periodic inspection is required as follows:
1. Inspect terminals for corrosion and loose connections.
2. Inspect wiring for frayed and worn insulation.
3. Check starter mounting bolts for tightness.
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-12 90-861329--1 MARCH 1999
PG260 Starter Motor
PG260 Specifications
Delco I.D. Number MerCruiser Part Number
9000820 50-806963
No Load Test
Brush Spring
Engine
Rotation
Volts
Min.
Amps
Max. Amp Min. rpm Max. rpm
Brush Spring
Tension Oz.
(Grams)
LH 10.6 60 95 2750 3250
83-104 oz. (2352-
2948)
Pinion Clearance .101-.160 (.025-4.06mm)
Bearing Depth (Gear) .011-.014 (0.28-.038mm) Maximum
Bearing Depth (Housing) .009-.017 (0.4mm) Maximum
Torque Specification
Fastener Location lb-ft Nm
Starter Mounting Bolts 30 41
Fastener Not Listed Tighten Securely
NOTE: The PG260 starter cannot be rebuilt. The only replacement components available
are the solenoid and drive housing.
Description
The Delco PG260 starter motor features small permanent magnets mounted inside the field
frame. These magnets take the place of current-carrying field coils mounted on iron pole
pieces. Internal gear reduction, approximately 4 to 1, through planetary gears results in
armature speeds in the 7000 rpm range. The armature and drive shaft are mounted on roller
or ball bearings in place of bushings. The solenoid switch, plunger, return spring, and shift
lever are permanently mounted in the drive housing.
CAUTION
The starter motor is designed to operate under great overload and produce a high
horsepower for its size. It can do this only for a short time, since considerable heat
accumulates and can cause serious damage. For this reason, the cranking motor
must never be used for more than 30 seconds at any one time. Cranking should not
be repeated without a pause of at least 2 minutes to permit the heat to escape.
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-13
PG260 Exploded View
74270
20
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
21
1-Screw (2)
2-End Cap
3-Brush With Holder
4-Armature
5-Field Frame (With Permanent Magnets)
6-Washer
7-Shield
8-Planetary Gears
9-Shaft
10 - Gear
11 - Drive
12 - Collar
13 - Retaining Ring
14 - Trust Collar
15 - Drive Housing
16 - Nut
17 - Solenoid
18 - Solenoid Drive Arm
19 - Screw (3)
20 - Screw (2)
21 - Rubber Grommet
INDEX
STARTING SYSTEM SERVICE MANUAL NUMBER 26
Page 4A-14 90-861329--1 MARCH 1999
Starter Motor Repair
Removal
WARNING
Disconnect battery cables at battery before removing starter.
1. Disconnect battery cables from battery.
2. Disconnect wires from solenoid terminals.
IMPORTANT: Some starter motors may use a special mounting shim for gaining fly-
wheel clearance. Do not lose this shim; it will be needed when remounting starter on
engine block.
3. Remove starter mounting bolts.
4. Pull starter assembly away from flywheel and remove from engine.
74523
a
a-Starter Bracket (If So Equipped)
Disassembly
1. Remove brush lead from solenoid and screws from end frame.
74041
a
b
a-Brush Lead
b-Screws
INDEX
STARTING SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4A-15
2. Remove through bolts and separate end frame from field frame and end cap.
74040
a
b
c
a-End Cap
b-Through Bolt
c-Drive Housing
3. Remove brush holder from end cap.
74037
a
b
c
a-Brush Holder
b-End Cap
c-Screws (2)
4. Remove armature and field frame from drive housing.
5. Pull armature out of field frame.
NOTE: Permanent magnets inside field frame will be holding armature in place.
74086
b
a
a-Armature
b-Field Frame
INDEX