OMC SAIL DRIVE BULLETIN #11
Service procedures for OMC Sail Drives are quite similar to those for
Evinrude or Johnson 25/35 H.P. outboards. There are, however, a few important differences
due to the type of installation, and the fact that OMC Sail Drives must meet U.S. Coast
Guard standards for inboard marine engines. The following pages will point out these
A. Removal of powerhead only (can be done with boat in water)
1. Disconnect battery, then remove battery cables at engine.
2. Remove exhaust hose from high rise elbow. See Figure 1, Item A.
3. Disconnect electrical plug. See Figure 1, Item B.
4. Disconnect temperature switch lead. See Figure 1, Item C.
5. Close fuel supply shut off valve.
6. Disconnect throttle cable at engine and store locking type fastener so it won't get lost or substituted.
7. Close water shut off valve. See Figure 1, Item D.
Note: If valve is not closed, and the water inlet hose or powerhead is removed, water will enter engine compartment.
8. Open water drain petcock and drain cylinder block. See Figure 3.
9. Remove water inlet hose from upper exhaust manifold. See Figure, Item E.
10. Remove water return hose from lower exhaust manifold. See Figure 1, Item F.
11. Disconnect fuel line at fuel pump and plug fuel line to prevent drainage. See Figure 2. Failure to plug fuel line may result in fuel spillage in engine compartment. Fire and explosion could
12. Remove four screws and two nuts attaching powerhead to adapter. See Figure 4.
13. Lift straight up to remove complete powerhead assembly.
Installation of powerhead
1. Reverse the procedures used to remove the powerhead in Section A.
2. Use a new gasket underneath the powerhead and coat it with OMC Gasket Sealing Compound. 3. Torque the nuts and bolts to 12-15 ft. lbs.
4. Run engine and check fuel system for leaks.
Removal of complete Sail Drive from boat.
Note: Boat must be removed from water. Failure to do so will allow water to flood boat and cause damage. Some installations, however, may not provide enough deck clearance to remove entire Sail Drive. In such cases, remove powerhead and lower unit separately.
1. Remove boat from water.
2. Remove propeller.
3. Perform Steps 1 thru 5 under "powerhead removal."
4. Disconnect fuel line at adapter housing and plug fuel line to prevent fuel drainage into engine compartment. See Figure 4. Failure to plug fuel line may result in fuel spillage in engine com partment. Fire and explosion could result.
5. Disconnect throttle and shift cables at engine and adapter housing. Store locking type fasteners
so they won't get lost or substituted.
6. Remove 8 screws from around mounting plate.
7. Lift Sail Drive up, then tilt powerhead aft to pass gearcase thru mounting fixture. Complete Sail Drive can now be removed from boat.
Installation of complete Sail Drive
1. Reinstall Sail Drive by reversing the procedure in Section C.
2. Install a new rubber gasket around mounting plate. Do not use any sealer.
3. Follow a criss-cross pattern and torque the mounting plate bolts to 15-20 ft. lbs. 4. Check for leaks.
5. Re-attach the shift and throttle cables using the locking type connectors provided. Do not i substitute these fasteners. Improper substitution of fasteners may result in control cables coming
loose. Operator may lose control of boat.
Removal of lower gearcase.
Note: Boat must be removed from water. Failure to do so will allow water to flood boat and cause damage.
1. Take out Sail Drive Following steps 1 thru 7 in Section C.
2. Remove powerhead as described in steps 6 thru 13 in Section A.
3. Remove the screws, nut, and the adapter housing from the intermediate. See Figure 5. At this
point, the water pump can be serviced.
4. Remove the shift lever shaft and its attaching hardware from the intermediate. See Figure 6. 5. Remove the five intermediate to gearcase bolts. See Figure 7.
Note: Be ready to catch gearcase. As bolts come free, it will drop out from under mounting plate.
Installation of lower gearcase
1. Reverse the procedures followed in Section E.
For more complete service information, refer to the OMC Sail Drive Service Manual.
WARNING: Failure to perform all the installation steps properly may result in leakage and possible sinking of boat.
Sail Drive Fuel System
Because the OMC Sail Drive is an inboard engine installation, its fuel components must meet U.S. Coast Guard requirements. Shown in Figure 8 are the major components that differ from an outboard fuel system.
1. A special flame resistant hose runs between the fuel fitting on the mounting plate up to the fuel pump. See Item A.
2. The fuel pump itself has a metal body and has tapped holes for pipe fittings. See Item B. 3. All fuel lines, elbows, nipples and fittings on the engine must be metallic. See Item C. 4. The carburetor float bowl is metal and is tapped to accept a pipe fitting. See Item D. 5. The air silencer, plug and gasket act as a fuel containment device. See Item E.
Warning: The carburetor air silencer also acts as a containment device in the event of fuel overflow from a malfunctioning carburetor. The fogging plug and gasket must be in place to complete this containment system.
6. In place of a fuel tank primer bulb, the Sail Drive uses a metal primer pump. See Item F.
7. The primer bowl must be metal and requires a special flame and fuel resistant seal. See Item G.
8. An anti-siphon valve is also required to prevent fuel spillage from the gas tank if a fuel line were to break. See Item H.
9. A heat shield (not shown) encloses and protects the fuel pump.
Note: Never replace Sail Drive fuel components with similar outboard parts. They are not the same. Fuel leakage may result.
Sail Drive Electrical System
Components and test procedures are quite similar to current 25/35 H.P. outboards. The starter motor, however, has been flash-proofed to meet U.S.C.G. requirements and must not be substituted with an out board equivalent. The optional alternator kit uses the current OMC Stern Drive alternator and solid state regulator.
In order to operate the engine starting system, a 12 volt (V) battery is required (not supplied with engine). For best performance, we recommend a 12 V, 70 ampere-hour battery or better, with a minimum of 2 minutes cold starting capacity at 300 amperes discharge, OoF (minus 17.8oC), and a 10 second voltage rating of 7.5V.
Ignition Timing Adjustment
Note: Some timing lights may not react properly because of the fast ignition rise time. If this occurs, check for proper plug, Champion L81Y. Check timing and re-gap spark plug for correct gap.
1. Connect a timing light to the No. 1 (top) cylinder. Start and run the engine at full armature advance.
2. The timing mark must align with the 24o mark on the flywheel grid within plus or minus 1o. See Figure 11.
3. Loosen the timing stop adjustment screw locknut, and turn the screw in or out as necessary to correct the timing.
4. Tighten the locknut, and re-check the timing adjustment.
Sail Drive Cooling System
Its function is similar to 25/35 H.P. outboard, however, water flow differs slightly (see Figure 9). One area that requires particular attention is the exhaust system. The exhaust hose between the elbow and muffler must not droop or pitch upward, instead it must slant downward directly to the muffler. The thru hull exhaust fitting must be a minimum 4 inches above the static water line, and the exhaust hose between the fitting and muffler must be looped upwards to prevent water entry. See Figure 10.
Warning: Check exhaust system for leaks. Carbon monoxide present in exhaust gases, is a colorless and odorless gas which can be fatal.
See Cooling system Diagram.
See Sail Drive water lift exhaust system.
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