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TABLE OF CONTENTS 1 TABLE OF CONTENTS 2 GENERAL MAINTENANCE COMPRESSION CHECK 2-3 IGNITON SYSTEM 2-4 CARBURETOR ADJUSTMENTS 2-7 FUEL PUMP 2-9 2-11 2-12 ST AR TER AND SOLENOID 2-10 INTERNAL WIRING HARNESS WATER PUMP CHECK PROPELLER 2-13 LOWER UNIT 2-14 BOAT TESTING 2-15 3 POWERHEAD POWERHEAD DISASSEMBLING 3-5 HEAD SERVICE 3-5 REED SERVICE 3-6 REED SERVICE 3-6 CRANKSHAFT 3-27 CYLINDER BLOCK SERVICE 3-28 4 FUEL TROUBLESHOOTING 4--4 CARBURETORS 4--12 TYPE I CARBURETOR 4--13 CHOKE SYSTEM SERVICE 4--23 TYPE II CARBURETOR 4--28 CHOKES TO TYPE II TYPE III CARBURETORS 4--43 5 IGNITION SPARK PLUG EVALUATION 5-2 POLARITY CHECK 5-3 WIRING HARNESS 5-4 6 ELECTRICAL AUTOLITE STARTER MOTOR 6-34 PRESTOLITE STARTER MOTOR 6-39 6-44 7 ACCESSORIES SHIFT BOXES OLD-STYLE DOUBLE LEVER NEW-STYLE SHIFT LEVER ELECTRIC GEAR BOXES 7-1 7-3 7-6 7-10 SINGLE LEVER CONTROL 7-12 8· LOWER UNIT LOWER UNIT SERVICE 1.5 hp to 4.0 hp -- Lowe Unit Removal Water Pump Removal Water Pump Installation Lower Unit Installation Filling the Lower Unit LOWER UNIT SERVICE 5 HP TO 25 HP Removal Water Pump Removal Disassembling Cleaning and Inspecting Assembling Water Pump Installation 9 HAND STARTERS TYPE I STARTER 9-11 TYPE II STARTER 9-17 TYPE III STARTER 10 APPENDIX SPECIFICATTIONS 8-8 8-9 8-10 8-15 8-16 8-16 8-17 8-19 8-19 8-20 8-22 8-28 8-31 2 MAINTENANCE 2-1 INTRODUCTION The efficiency, reliability, fuel economy and enjoyment available from engine performance are all directly dependent on having it tuned properly. The importance of performing service work in the sequence detailed in this chapter cannot be over emphasized. Before making any adjustments, check the Specifications in the Appendix. NEVER compression must be corrected or the tuneup will not give the desired results. rely on memory when making critical ad- and an inspection made, the cylinder will justments. require service. The opposite of poor compression would be to consider good compression as evidence of a satisfactory cylinder. However, this is not necessarily the case, when working on an outboard engine. As the professional mechanic has discovered, many times the compression check will indicate a satisfactory cylinder, but after the head is pulled Before beginning to tune any engine, check to be sure the engine has satisfactory compression. An engine with worn or broken piston rings, burned pistons, or badly scored cylinder walls, cannot be made to perform properly no matter how much time and expense is spent on the tune-up. Poor Damaged piston, probably caused by inaccurate fuel mixture, or improper point setting. A clean exterior engine appearance reflects this owner's pride in his unit. Keeping the interior well lubricated and properly adjusted will give him the enjoyment deserved for his investment. 2-2 TUNING A practical maintenance program that is followed throughout the year, is one of the best methods of ensuring the engine will give satisfactory performance at any time. The extent of the engine tune-up is usually dependent on the time lapse since the last service. A complete tune-up of the entire engine would entail almost all of the work outlined in this manual. A logical sequence of steps will be presented in general terms. If additional information or detailed service work is required, the chap- ter containing the instructions will be refer- enced. Each year higher compression ratios are built into modern outboard engines and the electr ical systems become more complex, especially with electronic (capacitor discharge) units. Therefore, the need for reliable, authoratative, and detailed instructions becomes more critical. The information in this chapter and the referenced chapters fulfill that requirement. 2-2 TUNE-UP SEQUENCE If twenty different mechanics were asked the question, "What constitutes a major and minor tune-up?", it is entirely possible twenty different answers would be given. As the terms are used in this manual and other Seloc outboard books, the following work is normally performed for a minor and major tune-up. Minor Tune-up Lubricate engine. Drain and replace gear oil. Adjust points. Adjust carburetor. Clean exterior surface of engine. Tank test engine for fine adjustments. The time, effort, and expense of a tune-up will not restore an engine to satisfactory performance, if the pistons are damaged. Major Tune-up Remove head. Clean carbon from pistons and cylinders. C lean and 0 ver haul carbu retor . Clean and overhaul fuel pump. Rebuild and adjust ignition system. Lubricate engine. Drain and replace gear oil. Clean exterior surface of engine. Tank test engine for fine adjustments. During a major tune-up, a definite sequence of service work should be followed to return the engine to the maximum performance desired. This type of work should not be confused with attempting to locate problem areas of "why'! the engine is not performing sat isfac tor ily, This work is classified as "troubleshooting". In many cases, these two areas will over lap, because many times a minor or major tune-up will correct the malfunction and return the system to normal operation. The following list is a suggested sequence of tasks to perform during the tuneup service work. The tasks are merely listed here. Generally procedures are given in subsequent sections of this chapter. For more detailed instructions, see the referenced chapter. 1- Perform a compression check of each cylinder. See Chapter 3. 2- Inspect the spark plugs to determine their condition. Test for adequate spark at the plug. See Chapter 5. 3- Start the engine in a body of water and check the water flow through the engine. See Chapter 8. 4-'- Check the gear oil in the lower unit. See Chapter 8. A boat and lower unit covered with marine growth. Such a condition is a serious hinderance to satisfactory performance. COMPRESSION CHECK 2-3 5- Check the carburetor adjustments and the need for an overhaul. See Chapter 4. 6- Check the fuel pump for adequate performance and delivery. See Chapter 4. 7- Make a general inspection of the igni- tion system. See Chapter 5. 8- Test the starter motor and the solenoid. See Chapter 6. 9- Check the internal wiring. 10- Check the synchronization. See Chapter 5. 2-3 COMPRESSION CHECK A compression check is extremely important, because an engine with low or uneven compression between cylinders CANNOT be tuned to operate satisfactorily. Therefore, it is essential that any compression problem be corrected before proceeding with the tune-up procedure. See Chapter 3. If the powerhead shows any indication of overheating, such as discolored or scorched paint, especially in the area of the top (No. l) cylinder, inspect the cylinders visually thru the transfer ports for possible scoring. A more thorough inspection can be made if the head is removed. It is possible for a cylinder with satisfactory compression to be scored slightly. Also, check the water pump. The overheating condition may be caused by a faulty water pump. Removing the spark plugs for inspection. Worn plugs are one of the major contributing factors to poor engine performance. An overheating condition may also be caused by running the engine out of the water. For unknown reasons, many operators have formed a bad habit of running a small engine withoutthe lower unit being submerged. Such a practice will result in an overheated condition in a matter of seconds. It is interesting to note, the same operator would never operate or allow anyone else to run a large horsepower engine without water circulating through the lower unit for cooling. Bear-in-mind, the laws governing operation and damage to a large unit ALL apply equally as well to the small engine. Checking Compression Remove the spark plug wires. AL WAYS grasp the molded cap and pull it loose with a twisting motion to prevent damage to the connection. Remove the spark plugs and keep them in ORDER by cylinder for evaluation later. Ground the spark plug leads to the engine to render the ignition system inoperative while performing the compression check. Insert a compression gauge into the No.1, top, spark plug opening. Crank the engine with the starter, or pull on the starter cord, thru at least 4 complete strokes with the throttle at the wide-open position, or until the highest possible reading is observed on the gauge. Record the reading. Repeat the test and record the compression for each cylinder. A variation A compression check should be. taken in each cylinder before spending time and money on tune-up work. Without adequate compression, efforts in other areas to regain engine performance will be wasted. 2-4 TUNING Damaged spark plugs. Notice the broken electrode on the left plug. The broken part must be found and removed before returning the engine to service. between cylinders is far more important than the actual readings. A variation of more than 5 psi between cylinders indicates the lower compression cylinder may be defective. The problem may be worn, broken, or sticking piston rings, scored pistons or worn cylinders. These problems may only be determined after the head has been removed. Removing the head on an outboard engine is not that big a deal and may save many hours of frustration and the cost of purchasing unnecessary parts to correct a faulty condition. 2-4 SPARK PLUG INSPECTION Inspect each spark plug for badly worn electrodes, glazed, broken, blistered, or lead fouled insulators. Replace all of the plugs, if one shows signs of excessive wear. Make an evaluation of the cylinder per- formance by comparing the spark condition with those shown in Chapter 5. Check each spark plug to be sure they are all of the same manufacturer and have the same heat range rating. FOULED ELECTRODES A foul spark plug. The condition of this plug indicates problems in the cylinder that should be corrected. Inspect the threads in the spark plug opening of the head and clean the threads before installing the plug. If the threads are damaged, the head should be removed and and a Hell-coil insert installed. If an attempt is made to drill out the opening with the head in place, some of the filings may fall into the cylinder and cause damage to the cylinder wall during operation. Because the head is made of aluminum, the filings cannot be removed with a magnet. When purchasing new spark plugs, AL- WAYS ask the marine dealer if there has been a spark plug change for the engine being serviced. Crank the engine through several revolutions to blowout any material which might have become dislodged during clean- mg. Install the spark plugs and tighten them to a torque value of 17 ft-lbs. ALWAYS use a new gasket and wipe the seats in the block clean. The gasket must be fully compressed on clean seats to complete the heat transfer process and to provide a gas tight seal in the cy Iinder, If the torque value is too high, the heat will dissipate too rapidly. Conversely, if the torque value is too low, heat will not dissipate fast enough. 2- 5 IGNITION SYSTEM Only one ignition system, a flywheelmagneto, is used on outboard engines covered in this manual. If the engine performance is less than expected, and the ignition is diagnosed as the problem area, refer to Chapter 5 for detailed service procedures. To properly synchronize the ignition system with the fuel system, see Chapter 5. Today, numerous type spark plugs are available for service. ALWAYS check with your local marine dealer to be sure you are purchasing the proper plugs for the engine being serviced. IGNITION SYSTEM 2-5 plugs will fire early; if adjusted with excessive gap, the plugs will fire too late, for efficient operation. Therefore, correct point adjustment and synchronization are essential for proper engine operation. An engine may be in apparent excellent mechanical condition, but perform poorly, unless the points and synchronization have been adjusted precisely, according to the Specifications in the Appendix. To synchronize the engine, see Chapter 5. Worn ignition points are a common problem area contributing to poor engine performance. Breaker Points Rough or discolored contact surfaces is sufficient reason for replacement. The cam follower will usually have worn away by the time the points have become unsatisfactory for efficient service. Check the resistance across the contacts. If the test indicates ZERO resistance, the points are serviceable. A slight resistance across the points will affect idle operation. A high resistance may cause the ignition system to malfunction and loss of spark. Therefore, if any resistance across the points is indicated, the point set should be replaced. 2-6 SYNCHRONIZING The timing on small OMC (Johnson and Evinr ude) outboard engines is controlled through adjustment of the points. If the points are adjusted too closely, the spark The fuel and ignition systems on any engine MUST be properly synchronized before maximum performance can be obtained from the unit. 2-7 BATTERY SERVICE Many owner/operators are not fully aware of the role a battery performs with a magneto ignition system outboard engine. To clarify: With a magneto ignition system, a battery is only used to crank the engine for starting purposes. Once the engine is running properly, the battery could very well be removed without affecting engine operation. Therefore, if the battery is completely dead, the engine may be hand started with a pull cord and operate efficiently. If a battery is used for starting, inspect and service the battery, cables and connections. Check for signs of corrosion. Inspect the battery case for cracks or bulges, dirt, acid, and electrolyte leakage. Check the electrolyte level in each cell. Fill each cell to the proper level with distilled water or water passed thru a demineralizer. The battery MUST be located near the engine in a well-ventilated area. It must be secured in such a manner that absolutely no movement is possible in any direction under the most violent action of the boat. 2-6 TUNING Clean the top of the battery. The top of a 12-volt battery should be kept especially clean of acid film and dirt, because of the high voltage between the battery terminals. For best results, first wash the battery with a diluted ammonia or baking soda solution to neutralize any acid present. Flush the solution off the battery with clean water. Keep the vent plugs tight to prevent the neutralizing solution or water from entering the cells. Check to be sure the battery is fastened securely in position. The hold-down device should be tight enough to prevent any movement of the battery in the holder, but not so tight as to place a strain on the battery case. If the battery posts or cable terminals are corroded, the cables should be cleaned separately with a baking soda solution and a wire brush. Apply a thin coating of Multi- purpose Lubricant to the posts and cable clamps before making the connections. The lubricant will help to prevent corrosion. If the battery has remained under-charged, check for high resistance in the charging circuit. If the battery appears to be using too much water, the battery may be defective, or it may be too small for the job. A check of the electrolyte in the battery should be a regular task on the maintenance schedule on any boat. An inexpensive brush should be purchased and used to clean the battery terminals. Clean terminals will ensure a proper connection. Jumper Cables If booster batteries are used for starting an engine the jumper cables must be connected correctly and in the proper sequence to prevent damage to either battery, or the al ternator diodes. AL WAYS connect a cable from the posi- tive terminals of the dead battery to the positive terminal of the good battery FIRST. NEXT, connect one end of the other cable to the negative terminals of the good battery and the other end of the ENGINE for a good ground. By making the ground connection on the engine, if there is an arc when you Common set of jumper cables for using a second battery to crank and start the engine. EXTREME care should be used when using a second battery, as explain- ed in the text. CARBURETOR ADJUSTMENT 2-7 make the connection it will not be near the battery. An arc near the battery could cause an explosion, destroying the battery and causing serious personal injury. If it is necessary to use a fast-charger on a dead battery, ALWAYS disconnect one of the boat cables from the battery first, to prevent burning out the diodes in the alternator. NEVER use a fast charger as a booster to start the engine because the diodes in the genera tor will be DAMAGED. Generator Charging Normally a generating system is not standard equipment on the smaller horsepower engines, up to the 35 hp model. However, a generator kit may be purchased and installed on the 35 hp and '+0 hp engines for battery charging while the engine is operating. A generator system is standard equipment on the '+0 hp electric shift model. When the battery is partially discharged, the ammeter should change from discharge to charge between 1500 to 1800 rpm for all models. If the battery is fully-charged, the rpm will be a little higher. With the engine running, in gear, in the water, increase the throttle until the rpm is approximately 5200 rpm. The ammeter reading should meet the Alternator Specifications in the Appendix. With a fullycharged battery the ammeter reading will be a bit lower because of the self-regulating characteristics of the generating systems. A 40 hp engine with a starter installed on the starbaord side and a generator on the port side. The generator, in kit form, is available from the local OMC dealer. Pressure-type fuel tank used on many outboard installations until the late 1950's. The text explains how to update such a system with a fuel pump and modern fuel tank. Before disconnecting the ammeter, remove the red harness lead connected to the positive battery terminal. For generating service, see Chapter 6. 2-8 CARBURETOR ADJUSTMENTS Fuel and Fuel Tanks Take time to check the fuel tank and all of the fuel lines, fittings, couplings, valves, flexible tank fill and vent. Turn on the fuel supply valve at the tank, if the engine is equipped with a self-contained fuel tank. If the gas was not drained at the end of the previous season, make a careful inspection for gum formation. When gasoline is allowed to stand for long periods of time, particularly in the presence of copper, gummy deposits form. This gum can clog the An ideal OMC fuel tank and fuel line arrangement. The tank is well secured and clean. The quick-disconnect device affords easy removal of the tank for fiZZing. 2-8 TUNING filters, lines, and passageway in the carburetor. If the condition of the fuel is in doubt, drain, clean, and fill the tank with fresh fuel. Fuel pressure at the carburetor should be checked whenever a lack of fuel volume at the carburetor is suspected. High-speed Adjustment The high-speed needle valve is adjustable on most models covered in this manual through1965. After 1965, the high-speed needle valve is fixed at the factory and is NOT adjustable. However, larger or smaller needle valves may be installed for different elevations. On all Johnson/Evinrude engines, the high-speed needle valve is the lower valve on the carburetor. The upper needle is always the idle adjustment. A beginning "rough" adjustment for the high-speed needle valve is 3/'+ turn out (counterclockwise) from the lightly seated (closed) position. TAKE CARE not to seat the valve firmly to prevent damage to the valve or the carburetor. To make the high-speed adjustment: a- Mount the engine in a test tank or body of water, preferably with a test wheel. Engines up to '+0 hp may be operated in the high rpm range in a test tank without sustaining damage. NEVER, AGAIN NEVER, operate the engine at high speed with a flush device attached. The engine, operating at high speed with such a device attached, would RUN-AWAY from lack of a load on the propeller, causing extensive damage. D- Connect a tachometer to the engine. A 35 hp unit showing location of the idle and highspeed adjustments. Notice the pressure-type fuel connector. CAUTION: Water must circulate through the lower unit to the engine any time the engine is run to prevent damage to the water pump in the lower unit. Just five seconds without water will damage the water pump. c- Start the engine and allow it to warm to operating temperature. d- Shift the engine into forward gear. e- With the engine running in forward gear, advance the throttle to the wide open position, and then very SLOWLY turn the high-speed needle valve inward (CLOCKWISE) until the engine begins to loose rpm. Now, SLOWLY rotate the needle valve outward (COUNTERCLOCKWISE) until the engine peaks out at the highest rpm. If the high-speed needle valve adjustment is too lean, the low-speed adjustment will be affected. Under certain conditions it may be necessary to adjust the high-speed needle valve just a bit richer in order to obtain a satisfactory idle adjustment. After the high-speed needle adjustment has been obtained, proceed with the idle adjustment as outlined in the next paragraphs. Idle Adjustment Due to local conditions, it may be neces- sary to adjust the carburetor while the engine is running in a test tank or with the boat in a body of water. For maximum performance, the idle mixture and the idle rpm should be adjusted under actual operating conditions. Set the idle mixture screw at the speci- fied number of turns open from a lightly seated position. In most cases this is from I to 1Y2 turns open from close. Small horsepower engine mounted in a test tank with the low- and high-speed adjustments indicated. FUEL PUMP 2-9 Start the engine and allow it to warm to operating temperature. CAUTION: Water must circulate through the lower unit to the engine any time the engine is run to prevent damage to the water pump in the lower unit. Just five seconds without water will damage the water pump. NEVER, AGAIN NEVER, operate the engine at high speed with a flush device attached. The engine, operating at high speed with such a device attached, would RUN-AWAY from lack of a load on the propeller, causing extensive damage. With t he engine running in forward gear, slow ly turn the idle mixture screw COUNTERCLOCKWISE until the affected cylinders start to load up or fire unevenly, due to an over-rich mixture. Slowly turn the idle mixture screw CLOCKWISE until the cylinders fire evenly and engine rpm increases. Continue to slowly turn the screw CLOCKWISE until too lean a mixture is obtained and the rpms fall off and the engine begins to misfire. Now, set the idle mixture screw one-quarter 0/4) turn out