Mercury Mercruiser Engines 305 CID 1998-2001 Full Service
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Number 24
Printed in U.S.A. 90-861327--1 1099 1999, Mercury Marine
GM V-8
305 CID (5.0L) / 350 CID (5.7L)
MARINE ENGINES
SERVICE
MANUAL
90-861327--1 OCTOBER 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.
Page ii 90-861327--1 OCTOBER 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.
Cleanliness and Care of Outboard Motor
A marine power product is a combination of many machined, honed, polished and lapped
surfaces with tolerances that are measured in the ten thousands of an inch/mm. When any
product component is serviced, care and cleanliness are important. Throughout this manu-
al, it should be understood that proper cleaning, and protection of machined surfaces and
friction areas is a part of the repair procedure. This is considered standard shop practice
even if not specifically stated.
Whenever components are removed for service, they should be retained in order. At the
time of installation, they should be installed in the same locations and with the same mating
surfaces as when removed.
Personnel should not work on or under an outboard which is suspended. Outboards should
be attached to work stands, or lowered to ground as soon as possible.
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.
1
2
3
4
5
6
7
8
9
Important Information
Removal and Installation
Engine
Electrical Systems
Fuel Systems
Cooling System
Exhaust System
Drives
Power Steering System
90-861327--1 OCTOBER 1999 Page iii
Service Manual Outline
Section 1 - Important Information
A - General Information
B - Maintenance
C - Troubleshooting
Section 2 - Removal and Installation
A - MCM Models
B - MIE Models
Section 3 - Engine
A - 350 cid / 5.0L/ 305 cid / 5.7L Engines
Section 4 - Electrical Systems
A - Starting System
B - Ignition System
C - Charging System
D - Instrumentation
E - Wiring Diagrams
Section 5 - Fuel Systems
A - Fuel Delivery System For Carbureted Engines
B - Mercarb 2 Barrel Carburetor
C - Fuel Delivery System For Electronic Fuel Injection
D - Fuel Injection Descriptions And System Operation
E - Fuel Injection Disassembly And Reassembly
F - Fuel Injection System Troubleshooting
G - Diagnostics
Section 6 - Cooling System
A - Seawater Cooled Models
B - Closed Cooled Models
Section 7 - Exhaust System
A - General
B - Manifolds, Elbows and Risers
C - Collectors
Section 8 - Drives
A - Velvet Drive In–Line and V-Drive Transmission
B - Velvet Drive 5000 Series Transmission
C - Hurth Models
D - Drive Shaft / Propeller Shaft Models
Section 9 - Power Steering System
A - Pump and Related Components
Page iv 90-861327--1 OCTOBER 1999
Table of Contents
IMPORTANT INFORMATION
Section 1A - General Information
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 . . . . . . . . . . . . . . .
Section 1B - Maintenance
Table of Contents 1B-1 . . . . . . . . . . . . . . . . . . .
Tools 1B-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 1B-2 . . . . .
Maintenance Schedules 1B-3 . . . . . . . . . . . . . .
Maintenance Intervals 1B-3 . . . . . . . . . . . . .
Engine and Tune-Up Specifications 1B-7 . . . .
Fluid Capacities 1B-11 . . . . . . . . . . . . . . . . . . . . .
Sterndrive Engines 1B-11 . . . . . . . . . . . . . . .
Inboard and Ski Engines 1B-11 . . . . . . . . . . .
Sterndrives 1B-11 . . . . . . . . . . . . . . . . . . . . . .
Transmission 1B-12 . . . . . . . . . . . . . . . . . . . . .
20-Hour Break-In Period 1B-13 . . . . . . . . . . . . .
After Break-in Period 1B-13 . . . . . . . . . . . . . . . .
End of First Season Checkup 1B-13 . . . . . . . . .
Specifications 1B-14 . . . . . . . . . . . . . . . . . . . . . . .
Fuel Recommendations 1B-14 . . . . . . . . . . .
Vapor locking 1B-14 . . . . . . . . . . . . . . . . . . . .
Test For Alcohol Content In Gasoline 1B-16
Procedure 1B-16 . . . . . . . . . . . . . . . . . . . . . . .
Transmission Fluid 1B-16 . . . . . . . . . . . . . . . . . .
Power Steering Fluid 1B-16 . . . . . . . . . . . . . . . .
Coolant for Closed Cooling System 1B-16 . . . .
Crankcase Oil 1B-17 . . . . . . . . . . . . . . . . . . . . . .
Overfilled Crankcase Oil 1B-17 . . . . . . . . . . .
Checking Engine Oil Level / Filling 1B-18 . .
Changing Oil and Filter 1B-18 . . . . . . . . . . . . . . .
Changing Water Separating Fuel Filter 1B-19 .
MCM (Sterndrive) Models 1B-19 . . . . . . . . . .
MIE (Inboard and Ski) Models 1B-20 . . . . . .
Power Steering System 1B-21 . . . . . . . . . . . . . .
Checking Fluid Level 1B-21 . . . . . . . . . . . . . .
Engine Warm 1B-21 . . . . . . . . . . . . . . . . . . . .
Engine Cold 1B-21 . . . . . . . . . . . . . . . . . . . . .
Filling and Bleeding 1B-22 . . . . . . . . . . . . . . .
Closed Cooling System 1B-23 . . . . . . . . . . . . . .
Checking Coolant Level 1B-23 . . . . . . . . . . .
Flushing System MCM (Sterndrive) 1B-24 .
Boat Out of Water 1B-24 . . . . . . . . . . . . . . . .
Boat In Water 1B-25 . . . . . . . . . . . . . . . . . . . .
Flushing System MIE
(Inboard and Ski) 1B-26 . . . . . . . . . . . . . . . .
Transmission Fluid 1B-27 . . . . . . . . . . . . . . . . . .
Lubrication 1B-28 . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Cable 1B-28 . . . . . . . . . . . . . . . . . . . .
Shift Cable and Transmission Linkage 1B-28
MCM (Sterndrive) Models 1B-28 . . . . . . . . . .
MIE (Inboard and Ski) Models 1B-29 . . . . . .
Engine Coupler/U-Joint Shaft Splines 1B-30
Sterndrive Drive Shaft
Extension Models 1B-31 . . . . . . . . . . . . . . . .
Starter Motor 1B-31 . . . . . . . . . . . . . . . . . . . . .
mie (Inboard and Ski) models 1B-31 . . . . . .
Cleaning Flame Arrestor 1B-32 . . . . . . . . . . . . .
Top Mounted Flame Arrestor 1B-32 . . . . . . .
Black Scorpion Flame Arrestor 1B-33 . . . . .
Serpentine Drive Belt 1B-34 . . . . . . . . . . . . . . . .
Component Location 1B-34 . . . . . . . . . . . . . .
Inspection 1B-36 . . . . . . . . . . . . . . . . . . . . . . .
Replacing and/or Adjusting Tension 1B-36 .
Removal 1B-36 . . . . . . . . . . . . . . . . . . . . . . . .
Installation and Adjustment 1B-36 . . . . . . . .
Ignition Timing 1B-37 . . . . . . . . . . . . . . . . . . . . . .
Thunderbolt V Models 1B-37 . . . . . . . . . . . . .
EFI/MPI Models 1B-38 . . . . . . . . . . . . . . . . . .
Cold Weather or Extended Storage 1B-39 . . . .
Precautions 1B-39 . . . . . . . . . . . . . . . . . . . . . .
Power Package Layup 1B-40 . . . . . . . . . . . .
Draining Instructions 1B-42 . . . . . . . . . . . . . .
Draining Seawater (Raw-Water)
Cooled Models 1B-42 . . . . . . . . . . . . . . . . . .
Draining Seawater Section of Closed
Cooled (Coolant) Models 1B-48 . . . . . . . . . .
Draining Seawater Section of Closed
Cooled (Coolant) Models 1B-50 . . . . . . . . . .
Draining Sterndrive 1B-52 . . . . . . . . . . . . . . .
Recommissioning 1B-53 . . . . . . . . . . . . . . . . .
90-861327--1 OCTOBER 1999 Page v
Section 1C - Troubleshooting
Used Spark Plug Analysis 1C-2 . . . . . . . . . . . .
Normal Condition 1C-2 . . . . . . . . . . . . . . . . .
Chipped Insulator 1C-2 . . . . . . . . . . . . . . . . .
Wet Fouling (Oil Deposits) 1C-3 . . . . . . . . .
Cold Fouling 1C-3 . . . . . . . . . . . . . . . . . . . . .
Overheating 1C-3 . . . . . . . . . . . . . . . . . . . . .
High Speed Glazing 1C-4 . . . . . . . . . . . . . . .
Scavenger Deposits 1C-4 . . . . . . . . . . . . . .
Pre-Ignition Damage 1C-4 . . . . . . . . . . . . . .
Reversed Coil Polarity 1C-5 . . . . . . . . . . . . .
Splashed Deposits 1C-5 . . . . . . . . . . . . . . . .
Mechanical Damage 1C-5 . . . . . . . . . . . . . .
Poor Boat Performance and/or
Poor Maneuverability 1C-6 . . . . . . . . . . . . . . . .
Improper Full Throttle Engine RPM 1C-7 . . . .
RPM Too High 1C-7 . . . . . . . . . . . . . . . . . . .
RPM Too Low 1C-7 . . . . . . . . . . . . . . . . . . . .
Engine Cranks Over but Will Not
Start or Starts Hard 1C-8 . . . . . . . . . . . . . . . . .
Important Information 1C-8 . . . . . . . . . . . . .
Testing Thunderbolt V
Ignition System 1C-9 . . . . . . . . . . . . . . . . . .
Fuel System Rich 1C-10 . . . . . . . . . . . . . . . . .
Fuel System Lean 1C-10 . . . . . . . . . . . . . . . .
Miscellaneous 1C-10 . . . . . . . . . . . . . . . . . . . .
Engine Will Not Crank Over 1C-11 . . . . . . . . . . .
Charging System Inoperative 1C-11 . . . . . . . . .
Noisy Alternator 1C-12 . . . . . . . . . . . . . . . . . . . . .
Instrumentation Malfunction 1C-12 . . . . . . . . . .
Radio Noise 1C-12 . . . . . . . . . . . . . . . . . . . . . . . .
Poor Fuel Economy 1C-13 . . . . . . . . . . . . . . . . .
Carburetor Malfunctions 1C-14 . . . . . . . . . . . . . .
Engine Runs Poorly at Idle 1C-15 . . . . . . . . . . .
Engine Runs Poorly At High RPM 1C-16 . . . . .
Engine Acceleration Is Poor 1C-17 . . . . . . . . . .
Troubleshooting with Vacuum Gauge 1C-17 . .
Engine Noise 1C-18 . . . . . . . . . . . . . . . . . . . . . . .
Important Information 1C-18 . . . . . . . . . . . . .
Valve Cover Area 1C-18 . . . . . . . . . . . . . . . . .
Cylinder Area 1C-19 . . . . . . . . . . . . . . . . . . . .
Camshaft Area 1C-19 . . . . . . . . . . . . . . . . . . .
Crankshaft Area 1C-20 . . . . . . . . . . . . . . . . . .
Miscellaneous 1C-21 . . . . . . . . . . . . . . . . . . . .
Oil Pressure 1C-22 . . . . . . . . . . . . . . . . . . . . . . . .
Low Oil Pressure 1C-23 . . . . . . . . . . . . . . . . .
High Oil Pressure 1C-23 . . . . . . . . . . . . . . . . .
Excessive Oil Consumption 1C-24 . . . . . . . . . . .
Water In Engine 1C-25 . . . . . . . . . . . . . . . . . . . . .
Important Information 1C-25 . . . . . . . . . . . . .
Water on Top of Pistons 1C-26 . . . . . . . . . . .
Water in Crankcase Oil 1C-26 . . . . . . . . . . . .
Engine Overheats (Mechanical) 1C-27 . . . . . . .
Engine Overheats (Cooling System) 1C-28 . . .
Insufficient Water Flow from Belt
Driven Seawater Pickup Pump 1C-29 . . . . .
Power Steering 1C-30 . . . . . . . . . . . . . . . . . . . . .
Poor, Erratic, or No Assist 1C-30 . . . . . . . . .
Noisy Pump 1C-31 . . . . . . . . . . . . . . . . . . . . . .
Fluid Leaks 1C-31 . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Silent Choice
Exhaust Silencer System 1C-32 . . . . . . . . . . . .
Compressor Will Not Run - Testing
Mode Switch 1C-33 . . . . . . . . . . . . . . . . . . . .
Compressor Will Not Run - Testing
Air Pump 1C-33 . . . . . . . . . . . . . . . . . . . . . . . .
Air Pump Runs - System Inoperative 1C-33
REMOVAL AND INSTALLATION
Section 2A - MCM Models
Torque Specifications 2A-2 . . . . . . . . . . . . . . . .
Tools 2A-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 2A-2 . . . . .
Preparation 2A-3 . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 2A-3 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 2A-5 . . . . . . . . . . . . . . . . . . . . . . . . .
Drive Shaft Extension Models 2A-7 . . . . . .
Engine Mount Adjustment Was
Not Disturbed During Service 2A-7 . . . . . .
Engine Mount Adjustment Was
Disturbed During Service 2A-10 . . . . . . . . . .
Alignment 2A-15 . . . . . . . . . . . . . . . . . . . . . . . . . .
Water Hose Connections 2A-17 . . . . . . . . . .
Electrical Connections 2A-18 . . . . . . . . . . . . .
Fuel Supply Connections 2A-20 . . . . . . . . . .
Throttle Cable Installation and
Adjustment 2A-21 . . . . . . . . . . . . . . . . . . . . . .
Power Steering Connections 2A-23 . . . . . . .
Exhaust Hose Connections 2A-24 . . . . . . . .
SECTION 2B - MIE Models
Identification 2B-2 . . . . . . . . . . . . . . . . . . . . . . . .
Velvet Drive In-Line and
V-Drive Transmissions 2B-2 . . . . . . . . . . . .
Velvet Drive
Down-Angle Transmission 2B-2 . . . . . . . . .
Hurth Transmissions 2B-3 . . . . . . . . . . . . . .
Torque Specifications 2B-3 . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 2B-4 . . . . .
Preparation 2B-4 . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 2B-4 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation and Alignment 2B-6 . . . . . . . . . . . .
Engine Final Alignment 2B-7 . . . . . . . . . . . .
Engine Connections 2B-10 . . . . . . . . . . . . . .
Attaching / Adjusting Reversed
Attachment Morse Shift Cables 2B-22 . . . . . . .
Page vi 90-861327--1 OCTOBER 1999
ENGINE
Section 3A - 350 cid / 5.0L/ 305 cid / 5.7L Engines
Torque Specifications 3A-3 . . . . . . . . . . . . . . . .
Tools 3A-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 3A-6 . . . . .
Specifications 3A-7 . . . . . . . . . . . . . . . . . . . . . . .
General Specifications 3A-7 . . . . . . . . . . . .
Engine Specifications 3A-8 . . . . . . . . . . . . .
General Information 3A-12 . . . . . . . . . . . . . . . . .
Repair Procedures 3A-12 . . . . . . . . . . . . . . . .
Engine Identification 3A-12 . . . . . . . . . . . . . .
Engine Rotation 3A-13 . . . . . . . . . . . . . . . . . .
Description 3A-13 . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft 3A-13 . . . . . . . . . . . . . . . . . . . . . . .
Piston and Connecting Rods 3A-13 . . . . . . .
Camshaft and Drive 3A-13 . . . . . . . . . . . . . . .
Cylinder Head 3A-14 . . . . . . . . . . . . . . . . . . . .
Valve Train 3A-14 . . . . . . . . . . . . . . . . . . . . . .
Intake Manifold 3A-14 . . . . . . . . . . . . . . . . . . .
Lubrication System 3A-14 . . . . . . . . . . . . . . .
Bearing Failures 3A-15 . . . . . . . . . . . . . . . . . . . .
Piston Failures 3A-17 . . . . . . . . . . . . . . . . . . . . . .
Pre-Ignition 3A-17 . . . . . . . . . . . . . . . . . . . . . .
Detonation 3A-18 . . . . . . . . . . . . . . . . . . . . . . .
Engine Mounts 3A-19 . . . . . . . . . . . . . . . . . . . . . .
Rocker Arm Cover 3A-21 . . . . . . . . . . . . . . . . . . .
Removal 3A-21 . . . . . . . . . . . . . . . . . . . . . . . .
Installation 3A-21 . . . . . . . . . . . . . . . . . . . . . . .
Intake Manifold 3A-22 . . . . . . . . . . . . . . . . . . . . .
Removal 3A-22 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-22 . . . . . . . . . . .
Installation 3A-23 . . . . . . . . . . . . . . . . . . . . . . .
Rocker Arm / Push Rod 3A-24 . . . . . . . . . . . . . .
Removal 3A-24 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-24 . . . . . . . . . . .
Installation 3A-24 . . . . . . . . . . . . . . . . . . . . . . .
Valve Adjustment 3A-25 . . . . . . . . . . . . . . . . . . . .
Engine Stopped 3A-25 . . . . . . . . . . . . . . . . . .
Engine Operating 3A-26 . . . . . . . . . . . . . . . . .
Hydraulic Valve Lifters 3A-27 . . . . . . . . . . . . . . .
Locating Noisy Lifters 3A-27 . . . . . . . . . . . . .
Removal 3A-28 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-29 . . . . . . . . . . .
Installation 3A-29 . . . . . . . . . . . . . . . . . . . . . . .
Valve Stem Oil Seal / Valve Spring 3A-30 . . . .
Removal - Head Installed 3A-30 . . . . . . . . . .
Valve Assembly (Exploded View) 3A-31 . . .
Installation - Head Installed 3A-31 . . . . . . . .
Cylinder Head 3A-32 . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-32 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-32 . . . . . . . . . . .
Installation 3A-33 . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Valve Conditioning 3A-34 .
Disassembly 3A-34 . . . . . . . . . . . . . . . . . . . . .
Valve Guide Bore Repair 3A-37 . . . . . . . . . .
Valve Springs - Checking Tension 3A-37 . . .
Rocker Arm Stud Replacement 3A-38 . . . . .
Valve Seat Repair 3A-39 . . . . . . . . . . . . . . . .
Valve Grinding 3A-40 . . . . . . . . . . . . . . . . . . .
Reassembly 3A-40 . . . . . . . . . . . . . . . . . . . . .
Crankcase Oil Dipstick Specifications 3A-43 . .
All Engines 3A-43 . . . . . . . . . . . . . . . . . . . . . .
Oil Pan 3A-45 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-45 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-45 . . . . . . . . . . .
Installation 3A-45 . . . . . . . . . . . . . . . . . . . . . . .
Oil Pump 3A-48 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exploded View 3A-48 . . . . . . . . . . . . . . . . . . .
Removal 3A-49 . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 3A-49 . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-49 . . . . . . . . . . .
Reassembly 3A-50 . . . . . . . . . . . . . . . . . . . . .
Installation 3A-50 . . . . . . . . . . . . . . . . . . . . . . .
Torsional Damper 3A-51 . . . . . . . . . . . . . . . . . . .
Installation 3A-51 . . . . . . . . . . . . . . . . . . . . . . .
Crankcase Front Cover/Oil Seal 3A-53 . . . . . . .
Oil Seal Replacement
(Without Removing Front Cover) 3A-53 . . .
Crankcase Front Cover 3A-54 . . . . . . . . . . . . . .
Removal 3A-54 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-54 . . . . . . . . . . .
Installation 3A-54 . . . . . . . . . . . . . . . . . . . . . . .
Flywheel 3A-56 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-56 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-57 . . . . . . . . . . .
Installation 3A-57 . . . . . . . . . . . . . . . . . . . . . . .
Rear Main Oil Seal 3A-58 . . . . . . . . . . . . . . . . . .
Removal 3A-58 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-59 . . . . . . . . . . .
Installation 3A-59 . . . . . . . . . . . . . . . . . . . . . . .
Rear Main Oil Seal Retainer 3A-60 . . . . . . . . . .
Removal 3A-60 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-60 . . . . . . . . . . .
Installation 3A-60 . . . . . . . . . . . . . . . . . . . . . . .
Main Bearings 3A-61 . . . . . . . . . . . . . . . . . . . . . .
Inspection 3A-61 . . . . . . . . . . . . . . . . . . . . . . .
Checking Clearances 3A-61 . . . . . . . . . . . . .
Replacement 3A-62 . . . . . . . . . . . . . . . . . . . . .
Connecting Rod Bearings 3A-65 . . . . . . . . . . . .
Inspection and Replacement 3A-65 . . . . . . .
Connecting Rod / Piston Assembly 3A-67 . . . .
Removal 3A-67 . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 3A-68 . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-68 . . . . . . . . . . .
Reassembly 3A-70 . . . . . . . . . . . . . . . . . . . . .
Installation 3A-72 . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft 3A-74 . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 3A-74 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 3A-76 . . . . . . . . . . .
Installation 3A-77 . . . . . . . . . . . . . . . . . . . . . . .
90-861327--1 OCTOBER 1999 Page vii
ELECTRICAL SYSTEMS
Section 4A - Starting System
Identification 4A-2 . . . . . . . . . . . . . . . . . . . . . . . .
Replacement Parts Warning 4A-2 . . . . . . . . . .
General Precautions 4A-2 . . . . . . . . . . . . . . . . .
Typical Starting System Components 4A-3 . .
Positive Current Flow 4A-4 . . . . . . . . . . . . . . . .
Battery 4A-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery Cable Recommendations 4A-4 . . .
Maintenance 4A-6 . . . . . . . . . . . . . . . . . . . . .
Testing 4A-7 . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage 4A-8 . . . . . . . . . . . . . . . . . . . . . . . . .
Charging Guide 4A-8 . . . . . . . . . . . . . . . . . .
How Temperature Affects
Battery Power 4A-9 . . . . . . . . . . . . . . . . . . .
Standard Starter Slave Solenoid 4A-9 . . . . . .
Identification 4A-9 . . . . . . . . . . . . . . . . . . . . .
Testing / Replacement 4A-10 . . . . . . . . . . . . .
Testing 4A-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starter Motor Voltage 4A-10 . . . . . . . . . . . . .
Voltage Drop In Starting System 4A-11 . . . .
Delco 14MT Direct Drive Starter 4A-12 . . . . . . .
Specifications 4A-12 . . . . . . . . . . . . . . . . . . . . . . .
Starter Specifications 4A-12 . . . . . . . . . . . . .
Torque Specifications 4A-12 . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 4A-12 . . . . .
Exploded View 4A-13 . . . . . . . . . . . . . . . . . . . . . .
Solenoid Switch 4A-14 . . . . . . . . . . . . . . . . . . . . .
Removal 4A-14 . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4A-14 . . . . . . . . . . . . . . . . . . . . . . .
Motor 4A-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 4A-14 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4A-14 . . . . . . . . . . .
Checking Pinion Clearance 4A-15 . . . . . . . .
Checking Commutator
End Frame Gap 4A-16 . . . . . . . . . . . . . . . . . .
Installation 4A-17 . . . . . . . . . . . . . . . . . . . . . . .
Delco PG260F1 Starter 4A-18 . . . . . . . . . . . . . .
Specifications 4A-18 . . . . . . . . . . . . . . . . . . . . . . .
Starter Specifications 4A-18 . . . . . . . . . . . . .
Torque Specifications 4A-18 . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 4A-18 . . . . .
Description 4A-18 . . . . . . . . . . . . . . . . . . . . . . . . .
Exploded View 4A-19 . . . . . . . . . . . . . . . . . . . . . .
Motor 4A-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 4A-20 . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4A-20 . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4A-24 . . . . . . . . . . .
Reassembly 4A-24 . . . . . . . . . . . . . . . . . . . . .
Checking Pinion Clearance 4A-28 . . . . . . . .
Installation 4A-29 . . . . . . . . . . . . . . . . . . . . . . .
Page viii 90-861327--1 OCTOBER 1999
Section 4B - Ignition System
Ignition Control System Components 4B-2 . .
Replacement Parts Warning 4B-2 . . . . . . . . . .
General Precautions 4B-2 . . . . . . . . . . . . . . . . .
EFI System Maintenance Precautions 4B-3 .
Torque Specifications 4B-3 . . . . . . . . . . . . . . . .
Tools 4B-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 4B-3 . . . . .
Ignition System Specifications 4B-4 . . . . . . . .
Distributor 4B-4 . . . . . . . . . . . . . . . . . . . . . . .
Coil 4B-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spark Plugs 4B-4 . . . . . . . . . . . . . . . . . . . . . .
Firing Order 4B-4 . . . . . . . . . . . . . . . . . . . . . .
Timing 4B-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thunderbolt V Models 4B-5 . . . . . . . . . . . . .
EFI / MPI Models 4B-6 . . . . . . . . . . . . . . . . .
Spark Plugs 4B-6 . . . . . . . . . . . . . . . . . . . . . . . .
Removal 4B-6 . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 4B-6 . . . . . . . . . . . . . . . . . . . . . . .
Replacing 4B-7 . . . . . . . . . . . . . . . . . . . . . . .
Spark Plug Wires 4B-8 . . . . . . . . . . . . . . . . . . . .
Inspection 4B-8 . . . . . . . . . . . . . . . . . . . . . . .
Replacing 4B-8 . . . . . . . . . . . . . . . . . . . . . . .
Ignition Coil 4B-9 . . . . . . . . . . . . . . . . . . . . . . . . .
Carbureted Engines -
Thunderbolt V Ignition 4B-11 . . . . . . . . . . . . . . .
Spark Control Features 4B-11 . . . . . . . . . . . .
Circuit Description 4B-12 . . . . . . . . . . . . . . . .
Thunderbolt V Spark Control Graph 4B-13 .
Ignition System Wiring Diagram 4B-14 . . . .
Thunderbolt V Ignition Module 4B-15 . . . . . .
Knock Control Module 4B-15 . . . . . . . . . . . . .
Mercury Marine Distributor 4B-17 . . . . . . . . . . .
Description 4B-17 . . . . . . . . . . . . . . . . . . . . . .
Exploded View 4B-17 . . . . . . . . . . . . . . . . . . .
Distributor Cap 4B-18 . . . . . . . . . . . . . . . . . . . . . .
Removal 4B-18 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4B-18 . . . . . . . . . . .
Installation 4B-18 . . . . . . . . . . . . . . . . . . . . . . .
Rotor / Sensor Wheel 4B-19 . . . . . . . . . . . . . . . .
Removal 4B-19 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4B-19 . . . . . . . . . . .
Installation 4B-20 . . . . . . . . . . . . . . . . . . . . . . .
Sensor 4B-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing 4B-21 . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 4B-21 . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4B-21 . . . . . . . . . . .
Installation 4B-22 . . . . . . . . . . . . . . . . . . . . . . .
Distributor Repair 4B-22 . . . . . . . . . . . . . . . . . . .
Removal 4B-22 . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4B-22 . . . . . . . . . . . . . . . . . . . . .
Reassembly 4B-22 . . . . . . . . . . . . . . . . . . . . .
Distributor Installation 4B-23 . . . . . . . . . . . . .
Replacing Distributor Gear 4B-25 . . . . . . . . . . .
Removal 4B-25 . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4B-25 . . . . . . . . . . . . . . . . . . . . . . .
GM EST Distributor 4B-26 . . . . . . . . . . . . . . . . . .
Removal 4B-26 . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4B-26 . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4B-27 . . . . . . . . . . .
Testing Pickup Coil 4B-28 . . . . . . . . . . . . . . .
Reassembly 4B-28 . . . . . . . . . . . . . . . . . . . . .
Installation 4B-29 . . . . . . . . . . . . . . . . . . . . . . .
Section 4C - Charging System
General Precautions 4C-2 . . . . . . . . . . . . . . . . .
EFI Electrical System Precautions 4C-2 . . . . .
Replacement Parts Warning 4C-2 . . . . . . . . . .
Multiple EFI Engine Battery Precautions 4C-3
Situation 4C-3 . . . . . . . . . . . . . . . . . . . . . . . . .
Recommendations 4C-3 . . . . . . . . . . . . . . . .
Identification 4C-4 . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 4C-4 . . . . . . . . . . . . . . . . . . . . . . .
Mando 4C-4 . . . . . . . . . . . . . . . . . . . . . . . . . .
DelcoRemy 4C-5 . . . . . . . . . . . . . . . . . . . . . .
Tools 4C-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 4C-5 . . . . .
Torque Specifications 4C-5 . . . . . . . . . . . . . . . .
Description 4C-6 . . . . . . . . . . . . . . . . . . . . . . . . .
Testing 4C-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charging System 4C-7 . . . . . . . . . . . . . . . . .
Charging System Resistance 4C-8 . . . . . . .
Circuitry 4C-10 . . . . . . . . . . . . . . . . . . . . . . . . .
Component 4C-11 . . . . . . . . . . . . . . . . . . . . . .
Exploded View 4C-16 . . . . . . . . . . . . . . . . . . . . . .
Alternator Repair 4C-17 . . . . . . . . . . . . . . . . . . . .
Removal 4C-17 . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4C-17 . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4C-22 . . . . . . . . . . .
Reassembly 4C-22 . . . . . . . . . . . . . . . . . . . . .
Installation 4C-26 . . . . . . . . . . . . . . . . . . . . . . . . .
Pulley Removal 4C-27 . . . . . . . . . . . . . . . . . .
Battery Isolator Diagram 4C-28 . . . . . . . . . . .
90-861327--1 OCTOBER 1999 Page ix
Section 4D - Instrumentation
Tools 4D-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 4D-2 . . . . .
Identification 4D-2 . . . . . . . . . . . . . . . . . . . . . . . .
Description 4D-3 . . . . . . . . . . . . . . . . . . . . . . . . .
Lighting Options 4D-3 . . . . . . . . . . . . . . . . . .
Gauges 4D-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuits 4D-4 . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil, Fuel and Temperature 4D-4 . . . . . . . . .
Battery Gauge 4D-6 . . . . . . . . . . . . . . . . . . .
Cruiselog Meter 4D-7 . . . . . . . . . . . . . . . . . .
Vacuum Gauge 4D-7 . . . . . . . . . . . . . . . . . . .
Speedometer 4D-8 . . . . . . . . . . . . . . . . . . . .
Tachometer 4D-8 . . . . . . . . . . . . . . . . . . . . . .
Gauge Replacement 4D-8 . . . . . . . . . . . . . . . . .
Senders 4D-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pressure 4D-9 . . . . . . . . . . . . . . . . . . . . .
Water Temperature 4D-10 . . . . . . . . . . . . . . .
Switches 4D-12 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Key Switch 4D-12 . . . . . . . . . . . . . . .
Lanyard Stop Switches 4D-13 . . . . . . . . . . . .
Start/Stop Switch 4D-14 . . . . . . . . . . . . . . . . .
Audio Warning System 4D-14 . . . . . . . . . . . . . . .
Buzzer 4D-14 . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pressure Switch 4D-15 . . . . . . . . . . . . . . .
Transmission Fluid
Temperature Switch 4D-15 . . . . . . . . . . . . . .
Sterndrive Gear Lube
Monitor Switch 4D-18 . . . . . . . . . . . . . . . . . . .
Section 4E - Wiring Diagrams
Starting and Charging Harness 4E-2 . . . . . . .
MCM 5.0L Engines 4E-2 . . . . . . . . . . . . . . .
MCM 5.7L Engines 4E-4 . . . . . . . . . . . . . . .
MEFI 1 and MEFI 2 MCM 5.0L EFI,
5.7L EFI and
350 Mag MPI Engines 4E-6 . . . . . . . . . . . .
MEFI 3 MCM 5.0L EFI, 5.7L EFI and
350 Mag MPI Engines 4E-8 . . . . . . . . . . . .
MIE 5.7L Inboard 4E-10 . . . . . . . . . . . . . . . . .
MIE 350 Mag MPI and Black Scorpion
Engines - Starting and Charging System
Harness 4E-12 . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel and Ignition System Harness 4E-14 . . . . .
MEFI 1 MCM 5.0L EFI,
5.7L EFI Alpha Engines 4E-14 . . . . . . . . . . .
MEFI 3 5.0L EFI and
5.7L EFI Engines 4E-15 . . . . . . . . . . . . . . . .
MEFI 1 and MEFI 2 MCM
350 Mag MPI Bravo Engines 4E-16 . . . . . .
MEFI 3 350 Magnum MPI and
All Black Scorpion Engines 4E-17 . . . . . . . .
FUEL SYSTEM
Section 5A - Fuel Delivery System For Carbureted Engines
Identification 5A-2 . . . . . . . . . . . . . . . . . . . . . . . .
Replacement Parts Warning 5A-2 . . . . . . . . . .
Specifications 5A-3 . . . . . . . . . . . . . . . . . . . . . . .
Torque Specifications 5A-2 . . . . . . . . . . . . . . . .
Tools 5A-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubricants / Sealants / Adhesives 5A-3 . . . . .
Precautions 5A-4 . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Supply Connections 5A-3 . . . . . . . . . .
Fuel Delivery System 5A-4 . . . . . . . . . . . . . . . .
Recommendations 5A-4 . . . . . . . . . . . . . . . .
Fuel System Components 5A-5 . . . . . . . . . . . .
Carburetor System 5A-5 . . . . . . . . . . . . . . . .
Water Separating Fuel Filter 5A-5 . . . . . . . . . .
Replacement 5A-6 . . . . . . . . . . . . . . . . . . . . .
Vent Hose Routing 5A-6 . . . . . . . . . . . . . . . . . .
Carbureted Models 5A-6 . . . . . . . . . . . . . . .
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Mercury Mercruiser Engines 305 CID 1998 1999 2000 2001 Full Service Repair Manual is a comprehensive guide containing all the necessary information for repairing, maintaining, rebuilding, refurbishing, or restoring Mercury Mercruiser Engines 305 CID 1998 1999 2000 2001. It covers diagnostic and repair procedures in great detail, making it useful for both professional technicians and do-it-yourself mechanics.
This manual is a series of practical repair and service manuals used by mechanics worldwide. It includes detailed sub-steps, notes, cautions, and warnings throughout each chapter, as well as numbered instructions and illustrations to guide users through every repair procedure. Troubleshooting and electrical service procedures are combined with detailed wiring diagrams for ease of use.
The manual is available in .PDF format and is compatible with all versions of Windows and Mac. It can be instantly accessed, saved to a hard drive, and printed if needed. It covers a wide range of topics including general information, specifications, engine removal, wiring diagrams, periodic maintenance, engine servicing, fuel and lubrication systems, electrical system, chassis, suspension, and much more.
Whether you are a professional technician or a DIY enthusiast, the Mercury Mercruiser Engines 305 CID 1998 1999 2000 2001 Full Service Repair Manual provides all the necessary information to effectively diagnose and repair problems with your engines.
