MerCruiser Alpha One Reference manual

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Printed in U.S.A.
service bulletin
No. 95-13
TO: SERVICE MANAGER TECHNICIANS
PARTS MANAGER
Alpha One Generation II Over Heat
Models
ALL
Situation
Over heat condition on Alpha One Generation II at 3000 RPM and above.
Trouble Shooting
Connect a clear plastic hose from the thermostat housing to the bottom of the exhaust manifold
on the starboard side of the engine. Take the boat out and water test it. Watch the clear hose for
air bubbles at around 3000 rpm and above. If the hose starts to fill with air bubbles, observe it until
it is about two thirds air bubbles and one third water. Watch the temperature gauge. It should begin
to show an increase in temperature. If no air bubbles appear and the water in the hose stays solid
with no air, you need to check other parts of the engine or transom.
Correction
Remove the drive from the boat, and separate the gear housing from the drive shaft housing. Re-
movethewaterpumptop,impeller,gasketsandfaceplate.Reinstallwithnewgasketsand(impeller
if required) using the following steps.
1. Coat the first gasket with Perfect Seal on the side that goes against the gear housing.
2. Place the face plate on top of the base gasket.
3. Place the top gasket on top of the face plate.
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4. Install the water pump alignment pins (91-821571A1) at this time to make sure that the water
pump top does not contact the drive shaft.
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5. Install the impeller key. Lightly lubricate the impeller with 2-4-C Marine Lubricant with Teflon
beforeinstallingovertheshaft.Ifreusingtheimpeller,makesurethatitisinstalledwiththe“vane
set” in the same direction as the unit turns to eliminate possible damage to the impeller vanes.
6. Reinstall the water pump top over the water pump alignment pins while turning the drive shaft
in the direction that the unit turns normally.
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7. With the alignment pins still in place, install two of the four water pump screws and torque to
60 lb. in. (6.7 N·m). Remove the alignment pins. Install the remaining screws and torque them
to 60 lb. in. (6.7 N·m).

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8. Lightlylubricatethedriveshaftwith2-4-CMarineLubricantwithTeflon.Placethefacesealover
the shaft. Use the installation tool that comes with a new face seal to position the seal at the
proper height.
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9. Lightly lubricate the O-rings in the water tube coupling with 2-4-C Marine Lubricant with Teflon.
Assemble the water tube sleeve into the water tube coupling.
10. Assemble the water tube coupling assembly to the water pump ensuring that the O-rings are
not damaged during assembly.
Warranty
Fill out warranty claim and send it to your normal warranty processing center.
Warranty Code and Labor:
MD30 2.0 Hours