1960-Onwards Sears Outboard Engine 3.5HP 75HP Service & Repair Manual

GLENN'S MARINE SERIES FULLY ILLUSTRATED HAROLD T. GLENN A COWLES BOOK

Other Books by Harold T. Glenn Youth at the Wheel Safe Living Automechanics Glenn's Auto Troubleshooting Guide Glenn's Triumph Repair and Tune-Up Guide Exploring Power Mechanics Glenn's Alfa Romeo Repair and Tune-Up Guide Glenn's Austin, Austin-Healey Repair and Tune-Up Guide Automobile Engine Rebuilding and Maintenance Glenn's Sunbeam-Hillman Repair and Tune-Up Guide Glenn's MG, Morris, and Magnette Repair and Tune-Up Guide Glenn's Volkswagen Repair and Tune-Up Guide Glenn's Volkswagen Repair and Tune-Up Guide (Spanish Edition) Glenn's Mercedes-Benz Repair and Tune-Up Guide Glenn's Foreign Carburetors and Electrical Systems Guide Glenn's Renault Repair and Tune-Up Guide Glenn's Jaguar Repair and Tune-Up Guide Automobile Power Accessories Glenn's Volvo Repair and Tune-Up Guide Glenn's Peugeot Repair and Tune-Up Guide Glenn's Auto Repair Manual Glenn's Foreign Car Repair Manual Glenn's Fiat Repair and Tune-Up Guide Automotive Smog Control Manual Honda Repair and Tune-Up Guide Copyright 0 1968 by HAROLD T. GLENN All rights reserved. This volume may not be reproduced in whole or in part in any Form without written permission from the publisher. I Printed in the United States of America 68A Library of Congress Catalog Number 68-9719

This is a comprehensive repair and tune-up manual for outboard motors. It is designed to be used' as a classroom text or mechanic's reference book, or it can be used by a boating enthusiast who is interested in keeping his engine in tip-top shape. A quick-starting and dependable engine can contribute to an enjoyable vacation; a balky engine can spoil the fun. This manual is organized about the conventional units of the outboard motor: the engine and the lower unit. Chapters are devoted to servicing the fuel and electrical systems. A separate chapter on engine tuning will enable the enthusiast to get all of the power from the engine that it was designed to deliver. A chapter on maintenance provides vital nontechnical information for fuel mixing and lubricating the units properly, to keep the engine operating dependably. The first chapter deals with troubleshooting. I t enables a mechanic to isolate trouble before beginning to disassemble the mechanism. It helps to pinpoint the trouble so that a mechanic will know what to look for as the unit is being disassembled. This feature can save valuable time when making repairs. This book contains comprehensive and accurate specification tables, wiring diagrams, and exploded views of all mechanical and electrical units. A special feature of this book is the use of many step-by-step illustrated instructions for representative types of carburetors, engines, and lower units. The illustrations and text are so closely correlated that no legends are needed. The illustrations have been especially treated to drop out the backgrounds. The author wishes to thank Messrs. Will Rush, Jack Carroll, Don Lideen, Bob Allman, and Paul Taylor for their kind assistance in helping to take the pictures and for furnishing technical information that has been used in this Guide. Especial thanks are due my wife, ANNA GLENN, for her devoted assistance in proof- reading the text. Harold T. Glenn

1 TROUBLESHOOTING Fuel system troubleshooting 1 Troubleshooting chart 2 Fuel system troubleshooting chart 3 Ignition troubleshooting 4 Ignition system troubleshooting chart 4 Compression 5 Compression troubleshooting chart 6 Rough operation 6 Rough operation troubleshooting chart 7 High fuel consumption 8 High fuel consumption troubleshooting chart 8 Noises Noise troubleshooting chart Mechanical problems Mechanical troubleshooting chart Cooling system troubleshooting chart Electrical system troubles Battery troubleshooting chart Ignition system troubleshooting chart Starting motor troubleshooting chart Troubleshooting the cranking motor Starter-generator troubleshooting chart Cranking motor troubleshooting chart 2 MAINTENANCE Boat performance and propeller selection Boat speed Center of gravity Tilt angle Transom height Condition of boat bottom Propeller selection Fuel consumption Installing the propeller Ti1 t pin adjustment Cavitation Caution for shallow water operation Performance factors Fuel mixing procedure Fuel mixing chart Water pump operation Stopping Removing the engine from the boat Maintenance Lubrication Fuel filter Lubrication chart Operating in salt water or silt After submersion Storage Using a cleaner Water wisdom Coast Guard regulations Rules of the waterways Signposts Seamanship for safety Stepping into the boat Casting off Weather signals 8 Rough water 8 Danger zone 9 Overtaking 9 Turns 9 Reverse gear 10 Skiing 10 Stopping 10 Docking 10 3 TUNING FOR PERFORMANCE 11 General ignition service procedures 29 11 Spark plug 29 11 Spark plug troubles 31 Spark plug protectors 33 15 Magneto service procedures 33 15 Removing the flywheel 33 15 Breaker point service 33 15 Breaker point synchronization 34 15 Ignition timing 34 15 Tune-up specifications 35 16 Carburetor throttle pickup adjustment 36 17 One-cylinder tune-up service procedures; 13 3.5 and 4 H P engines 36 17 Breaker point service 36 18 Carburetor adjustments 37 18 Two-cylinder engine tune-up service procedures; 18 7.5, 9, and 12/14 H p engines 37 19 Breaker point service 39 19 Carburetor-timing synchronous adjustment 39 20 Carburetor adjustments 39 20 Two-cyIinder engine tune-up service procedures; 2 1 25/28 Hp engines 40 2 1 Breaker point service 40 2 1 Carburetor-timing synchronous adjustment 41 2 1 Neutral speed limit adjustment 4 1 22 Carburetor adjustments 41

Two-cylinder tune-up service procedures ; 40-45 H p engines 41 Vacuum and throttle switch adjustments 42 Shift-limit switch 43 Ignition service procedures 43 Maximum spark advance adjustment 45 Carburetor-timing synchronous adjustment 46 Vacuum lift-off choke 50 Carburetor adjustmehts 50 High-speed adjustment 50 Altitude trimmer 5 1 Three-cylinder engine tune-up service procedures ; 75 Hp engine Shift-limit switch Distributor service Carburetor-timing synchronous adjustment Carburetor adjustments Altitude trimmer 4 FUEL SYSTEM SERVICE Fuel pump Fuel pump operation Fuel pump pressure test Fuel pump specifications Fuel pump, R&R Fuel tank maintenance Storage Walbro carburetors Walbro carburetor with an adjustable high-speed jkt; 3.5,4, and 14 H p engines Theory of operation Overhauling a Walbro carburetor with an adjustable high-speed jet Disassembling Cleaning and inspecting Assembling Walbro carburetor with a fixed high-speed jet ; 28, 45 (since l968), and 75 Hp engine Theory of operation Idle operation Mid-range operation High-speed operation Overhauling a Walbro carburetor with a Zxed high-speed jet Disassembling Cleaning and inspecting Assembling Marvel-Schebler carburetors Marvel-Schebler, type VHD, carburetor ; 45 H p engine Idle operation Intermediate operation High-speed operation Economizer system Accelerating system Overhauling a Marvel-Schebler, type VHD, carburetor Disassembling Cleaning and inspecting Assembling Marvel-Schebler, type SUM; 7.5 and 9 H p engines Overhauling a Marvel-Schebler, type SUM, carburetor Disassembling - 5 1 Cleaning and inspecting 5 1 Assembling 52 5 ENGINE SERVICE 53 Principles of operation 80 55 Engine details 8 1 55 General instructions 82 Mechanical engine specifications 83 56 Disassembling 83 56 Cleaning and inspecting 88 56 Assembling 9 1 56 Overhauling a two-cylinder, 7.5 and 9 H p engine 100 57 Disassembling 100 57 Cleaning and inspecting 104 57 Assembling 107 57 75, 45, 28, 14, and 3.5 engine service notes 117 75 and 45 H p engine service notes 117 57 28 H p engine service notes 119 57 14 H p engine service notes 121 3.5 Hp engine service notes 123 58 58 6 SERVICING THE LOWER UNIT 59 Description 59 Service procedures One-cylinder engine 61 Disassembling 61 Cleaning and inspecting 6 1 Assembling 62 Two-cylinder engine 62 Disassembling Cleaning and inspecting 63 Assembling 63 12 and 14 Hp lower unit 63 25 and 28 Hp lower unit 64 40, 43, 45, 60 and 75 H p lower unit 66 7 ELECTRICAL SYSTEM SERVICE Cranking motors 66 Overhauling a Delco-Remy cranking motor 66 Disassembling 67 Cleaning and inspecting 67 Assembling

Overhauling a Prestolite cranking motor Disassembling Cleaning and inspecting Assembling Starter-generator; 7.5 and 9 H p engines , Normal starting Charging Start button depressed accidentally Starter-generator troubleshooting Battery service Electrical tests Starter-generator service Output test Solenoid output test Sclenoid energizing test Diode test Starter-generator, R&R Cleaning and inspecting Brush holders and field windings Armature Diodes Assembling Alternator Alternator tests 28 and 45 Hp engine wiring diagram Selenium rectifier tests 75 H p engine wiring diagram

When the engine won't start, it is very important to Remove a spark plug to check its condition. A wet be able to run through an organized procedure in order spark plug means that the engine has been overchoked; to pinpoint the cause of the trouble. Bgsically, starting a dry spark plug means that no fuel is reaching the com- troubles can be localized to either the fuel system or the bustion chamber. If the carburetor fuel bowl is full, but ignition system. After isolating the trouble to the defec- the spark plug is dry, the carburetor jets may be plugged. tive system, go through the following suggested check If the spark plug is wet, go through the procedure list to determine the exact cause. for starting a flooded engine. Disconnect the fuel line or shut off the fuel supply completely, and then spin the flywheel several times to remove the excess fuel from the combustion chambers. Reconnect the fuel line, replace the spark plug, and then start the engine in the normal manner. FUEL SYSTEM TROUBLESHOOTING First make sure that there is gasoline in the tank. Sometimes the fuel supply burns up faster than you realize. On engines with a remote fuel tank, make sure that the air vent screw on the fuel tank cap is open, and then squeeze the priming bulb in the fuel line. When the carburetor float bowl is full of gasoline, pressure will be felt on the priming bulb. However, it is possible to force fuel past the needle and seat by additional pressure so that gasoline will flow out of the carburetor throat. CAUTION: The fuel will leak onto parts of the engine and could cause a fire. Make sure that all the gasoline is dried up before attempting to start the engine again. If the carburetor float bowl is dry, check the line for an obstruction. Do this by disconnecting the fuel line from the engine quick-disconnect fitting, and then de- pressing the check valve in the fuel line connection. Squeeze the bulb and fuel should come out of the line, if it is not obstructed. If the fuel line to the engine is clear, the trouble could be in the line to the fuel pump or to the carburetor, usually at the fuel line strainer. To check this out, disconnect the fuel line at the carburetor and see if you can force fuel through it by squeezing the priming bulb. CAUTION: When disconnecting a fuel line, use the proper wrenches, never a pair of pliers. CAUTION: When replacing a fuel line, don't tighten the nuts too much, especially on aluminum castings where the threads can be stripped rather easily. \ dl" A primer bulb is used to lift fuel from a remote gas tank in order to prime the carburetor. If the carburetor runs out of fuel, the fuel pump may be defective, but the engine can be run by using the primer bulb as a fuel pump.

FUEL SYSTEM 3 Some of the one-cylinder engine carbureton have a drain valve, which can be depressed to determine whether or not fuel is flowing to the carburetor. The drain valve should be depressed periodically to drain water and debris accumulations from the bowl. Check the fuel in the carburetor to see if water has gotten into it by catching a little of the gasoline in the palm of your hand. The water will appear as small beads or bubbles. If you blow on the mixture, the gasoline will evaporate, leaving the water behind. FUEL SYSTEM TROUBLESHOOTING CHART 1. No fuel in carburetor la. Empty gas tank I b. Clogged fuel filter Ic. Restricted vent in gas tank Id. Defective fuel pump The condition of the firing end of a spark plug can be used to determine the condition inside of the combustion chamber. This spark plug is running dry, meaning that the mixture is combustible and that the spark plug is doing its work well. To see if the he1 pump is working, disconnect the fuel line and direct its flow into a container. You should be able to determine the condition of the pump before the carburetor fuel bowl runs out of fuel. le. Main adjusting screw closed If. Clogged carburetor screen Ig. Clogged or broken fuel line 2. Fuel in carburetor 2a. Flooding at carburetor 2b. Choke not operating 2c. Water in gasoline 2d. Restricted carburetor jets 3. Flooding 3a. Choke out of adjustment The firing end of this spark plug is black with carbon and wet, indicat- ing that the fuel mixture contains too much oil, the fuel mixture is too rich, or the spark plug is not firing.

1960-Onwards Sears Outboard Engine 3.5HP 75HP Service & Repair Manual

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