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Mercury MerCruiser GM V8 Marine Engines (5.0L/5.7L) OEM Service & Repair Manual
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Number 17
Printed in U.S.A. 90-823225--1 1096 1996, Mercury Marine
GM V-8
305 CID (5.0L) / 350 CID (5.7L)
MARINE ENGINES
SERVICE
MANUAL
Book 1 of 2
Sections 1 thru 4

90-823225--1 1096 i
Notice
Throughout this publication, “Dangers,” “Warnings”
and “Cautions” are used to alert the mechanic to spe-
cial instructions concerning a particular service or
operation that may be hazardous if performed incor-
rectly or carelessly. Observe them carefully!
These “Safety Alerts” alone cannot eliminate the haz-
ards that they signal. Strict compliance to these spe-
cial instructions when performing the service, plus
“common sense” operation, are major accident pre-
vention 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 injury or death.
!
CAUTION
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 per-
sonnel when servicing the products described here-
in.
It is assumed that these personnel are familiar with
the servicing procedures of these products, of like or
similar products manufactured and marketed by
Mercury Marine, and that they have been trained in
the recommended servicing procedures for these
products which include the use of mechanic’s
common hand tools and the special Mercury
Marine or recommended tools from other suppliers.
We could not possibly know of and advise the service
trade of all conceivable procedures by which a ser-
vice might be performed and of the possible hazards
and/or results of each method. We have not under-
taken 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 product’s safety will be endangered by the ser-
vice procedure selected.
All information, illustrations and specifications con-
tained in this manual are based on the latest product
information available at time of publication.
It should be kept in mind, while working on the prod-
uct, that the electrical system and ignition system are
capable of violent and damaging short circuits or se-
vere 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 inter-
nal damage when the engine is started.
It is important to note that, during any mainte-
nance procedure, replacement fasteners must have
the same measurements and strength as those re-
moved, whether metric or customary. Numbers on
the heads of the metric bolts and on surfaces of met-
ric nuts indicate their strength. Customary bolts use
radial lines for this purpose, while most custom-
ary nuts do not have strength markings. Mismatched
or incorrect fasteners can result in damage or mal-
function, or possible personal injury. Therefore, fas-
teners removed should be saved for re-use in the
same locations whenever possible. Where the fas-
teners are not satisfactory for re-use, care should be
taken to select a replacement that meets the
same specifications as the original.

90-823225--1 1096 ii
Engine Mechanical
Components
Many of the engine mechanical components are de-
signed for marine applications. Unlike automotive
engines, marine engines are subjected to extended
periods of heavy load and wide-open-throttle opera-
tion and, therefore, require heavy-duty components.
Special marine engine parts have design and man-
ufacturing specifications which are required to pro-
vide 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 cor-
rode standard automotive parts within a short period
of time.
Failure to use recommended Quicksilver service re-
placement parts can result in poor engine perform-
ance and/or durability, rapid corrosion of parts sub-
jected to salt water and possibly complete failure of
the engine.
Use of parts other than recommended service re-
placement parts, will void the warranty on those parts
which are damaged as a result of the use of other
than recommended replacement parts.
Replacement Parts
!
WARNING
Electrical, ignition and fuel system components
on MerCruiser Engines and Stern Drives are de-
signed 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 com-
ponents are properly installed and tightened. If
not, any electrical or ignition component open-
ing would permit sparks to ignite fuel va-
pors from fuel system leaks, if they existed.

90-823225--1 1096 iii
Models Covered in This Manual
MCM Alpha
MODEL SERIAL NUMBER MODEL YEAR
5.0L OD832472 - OF601000
1993 199 5.0LX OD831003 - OF601000 1993 - 1995
5.7L (4 Barrel) OD830700 - OF601000
5.7L (2 Barrel) OF601000 and Above
1996 Th 199
5.7LX OF601957 and Above
1996 Th 199
5.7L EFI OF286830 and Above
1996 Thru 1997
5.7LX EFI OF752400 and Above
1996 Thru 1997
350 Magnum OD830982 and Above
350 Magnum EFI Gen+ OF800500 and Above
MCM Bravo
MODEL SERIAL NUMBER MODEL YEAR
5.0L OD833077 - OF601464
1993 - 1995
5.7L (4 Barrel) OD831826 - OF605335
1993 - 1995
5.7L (2 Barrel) OF605336 and Above
1996 Th 199
5.7LX OF601645 and Above
1996 Th 199
5.7L EFI OF225560 and Above
1996 Thru 1997
5.7LX EFI OF752408 and Above
1996 Thru 1997
350 Magnum OD800300 and Above
350 Magnum EFI Gen+ OF800500 and Above
350 Magnum EFI/MP OF289431 - OF601999 1995
350 Magnum MPI Gen+ OF602000 and Above 1996 Thru 1997

90-823225--1 1096 iv
MIE Ski
MODEL SERIAL NUMBER MODEL YEAR
5.7L Competition (4 Barrel) OD840220 - OF775199 1993 - 1995
5.7L Competition (2 Barrel) OF775200 and Above 1996 Thru 1997
350 Magnum Tournanment Ski OD840100 and Above 1993 Thru 1997
350 Magnum EFI Tournament Ski OF225157 - OK000000 1994 - 1996
350 Magnum EFI Gen+
Tournament Ski
OK040006 and Above 1997
350 Magnum EFI/MP
Tournament Ski
OF350583 - OF745536 1995
350 Magnum MPI Tournament Ski OF745537 - OK000000 1996
350 Magnum MPI Gen+
Tournament Ski (Black Scorpion)
OF800000 and Above 1996
MIE Inboard
MODEL SERIAL NUMBER MODEL YEAR
5.7L OD84000 and Above 1993 Thru 1997
5.7L EFI Gen+ OK040300 and Above 1997

Important
Information
8
1
2
3
4
5
6
7
9
Removal and
Installation
Engine
Electrical Systems
Fuel System
Cooling System
Exhaust System
Drives
Power Steering
90-823225--1 1096 v
Service Manual Outline
Section 1 - Important Information
A - Specifications
B - Maintenance
C - General Information
Section 2 - Removal and Installation
A - MCM Models - Alpha One Drives
B - MCM Models - Alpha One Drives with Driveshaft Extension
C - MCM Models - Bravo Drives
D - MCM Models - Bravo Drives with Driveshaft Extension
E - MIE Models - Velvet Drive Transmissions
F - MIE Models - Hurth Transmissions
Section 3 - Engine
A - 5.0L / 305 CID / 5.7L /350 CID
Section 4 - Electrical Systems
A - Starting System
B - Ignition System
C - Charging System
D - Instrumentation
E - Electrical Kits
F - Wiring Diagrams
Section 5 - Fuel System
A - Fuel Delivery Systems and Fuel Pumps
B - MerCarb 2 Barrel Carburetor
C - Rochester 4 Barrel Carburetor
D - Weber 4 Barrel Carburetor
E - Electronic Fuel Injection (Throttle Body and Multi-Port)
F - BOS / SAV Emission
Section 6 - Cooling System
A - Seawater Cooled Models
B - Closed Cooled Models
Section 7 - Exhaust System
A - General
B - Manifold and Elbows
C - Risers
D - Collectors
Section 8 - Drives
A - Borg-Warner In-Line Transmission
B - Borg-Warner V-Drive Transmission
C - Hurth Down Angle Transmission
D - Drive Shaft Models/Propeller Shaft
Section 9 - Power Steering
A - Pump

A
1
72000
IMPORTANT INFORMATION
GENERAL INFORMATION

1A-0 –GENERAL INFORMATION 90-823225--1 1096
Table of Contents
Page
Introduction 1A-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
How to Use This Manual 1A-1 . . . . . . . . . . . . . . . . . .
Page Numbering 1A-1 . . . . . . . . . . . . . . . . . . . . . .
How to Read Parts Manual 1A-2 . . . . . . . . . . . . . . . .
Directional References 1A-3 . . . . . . . . . . . . . . . . . . . .
Engine Rotation 1A-3 . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Serial Number Locations 1A-3 . . . . . . . . . . .
Propeller Information 1A-4 . . . . . . . . . . . . . . . . . . . . .
Water Testing New Engines 1A-4 . . . . . . . . . . . . . . .
Boat and Engine Performance 1A-4 . . . . . . . . . . . . .
Boat Bottom 1A-4 . . . . . . . . . . . . . . . . . . . . . . . . . .
Marine Fouling 1A-5 . . . . . . . . . . . . . . . . . . . . . . . .
Weight Distribution 1A-6 . . . . . . . . . . . . . . . . . . . . .
Water in Boat 1A-6 . . . . . . . . . . . . . . . . . . . . . . . . .
Elevation and Climate 1A-7 . . . . . . . . . . . . . . . . . .
NOTICE
For information and procedures on
troubleshooting, refer to Section 1C.

GENERAL INFORMATION - 1A-1 90-823225--1 1096
NOTICE
Refer to appropriate Stern Drive Service
Manual for transom assembly and stern
drive unit repair.
Introduction
This comprehensive overhaul and repair manual is
designed as a service guide for the models previous-
ly listed. It provides specific information, including
procedures for disassembly, inspection, assembly
and adjustment to enable dealers and service me-
chanics to repair and tune these engines.
Before attempting repairs or tune-up, it is suggested
that the procedure first be read through to gain knowl-
edge 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.
Page Numbering
Two number groups appear at the bottom of each
page. Following is an example and description.
72426

1A-2 –GENERAL INFORMATION 90-823225--1 1096
How to Read Parts Manual
841-81631 1 CYLINDER BLOCK ASSEMBLY 1
N.S.S. 2 PLUG, expansion (1-1/4”) (GM #3738306) 2
22-87238 3 DRAIN COCK, cylinder block 2
19-34270 4 PLUG, expansion - cylinder block (1-5/8” Diameter) 8
17-35465 5 PIN, dowel - block to head (5/16” Diameter) 4
22-72640 6 PLUG, expansion - camshaft bearing hole 1
23-85674 7 BEARING UNIT, camshaft (set) 1
72638 8 LIFTER, hydraulic valve 16
431-5943 9 CAMSHAFT 1
35378 10 CHAIN, camshaft timing 1
43-35338 11 SPROCKET, camshaft timing 1
43-48338 12 SPROCKET, crankshaft timing 1
10-34505 13 BOLT, camshaft timing sprockets (3/4”) 3
12-39167 14 WASHER, camshaft timing sprocket bolt 3
841-8163 Cylinder Block Assembly includes only standard pistons,
piston rings, crankshaft bearings and camshaft bearings.
PART NO.
REF.
NO. DESCRIPTION QUAN.
a
A. Part Number: For part ordering - Note N.S.S. for Reference Number 2, Plug, expansion - that means Not Sold Separately by Mercury Marine
however, in this case, the G.M. Part Number (for the plug) is given in the Description Column.
B. Reference Number: For part Shown on exploded parts view.
C. Description: This is the most important column because it gives:
1) Description of Part: Ref. No. 1 is a Cylinder Block Assembly, No. 9 is a Camshaft, etc.
2) What parts are included with a certain part: Notice how the Description of Part, for Ref. Nos. 1 and 8 thru 14, are at the left side of the column.
Description of Part for Ref. Nos. 2 thru 7 are indented under “Cylinder Block Assembly”. If Ref. No. 1 (Cylinder Block Assembly) was ordered,
all indented parts (Ref. Nos 2thru 7) would come with the part. Ref. Nos. 8 thru 14 would not come with Ref. No. 1 and would have to be ordered
separately. If 2 Cylinder Blocks were listed, both cylinder blocks would come with the indented parts. In some cases, an indented part will have
another part indented under it. The second indented part will come with the first indented part.
3) Serial number break: If serial number information is listed, check product serial number to ensure that correct part is ordered.
4) Special information: Many times special information will be shown after description such as; L.H. Rotation, R. H. Rotation, Filter up, Filter Down,
etc. This will help in selecting the correct part.
D. Quantity: Quantity that has to be ordered.
E. Special Information Block: Additional information, part numbers for gasket sets, etc.
M0033-D8
b
c
d
e
CYLINDER BLOCK AND CAMSHAFT
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$31.99
Instantly access the Mercury MerCruiser GM V8 Marine Engines (5.0L/5.7L) OEM Service & Repair Manual, designed for professional mechanics, technicians, and DIY enthusiasts alike. This professional manual provides comprehensive repair, maintenance, and troubleshooting procedures specifically for Mercury MerCruiser GM V8 engines.
Key features include:
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