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1978 Mercury 40 HP #M402

J

joeccraft

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" Hi guys, Any hints on replac

" Hi guys, Any hints on replacing a water pump and thermostat on this engine? I have worked on a ton of old Evinrude and Johnson 40HP's but this is a different beast altogether. Appreciate any help or suggestions on removing the lower unit and disconnecting/reconnecting the shift rod.
Thanks
Joe "
 
" Remove the bolts the usual w

" Remove the bolts the usual way. Dont forget the bolt under the trim tab. No need to disconnect the shift shaft, it is splined and will release. If you have bad luck, the drive shaft splines might be frozen. Are you shure it is a 1978? If older than 1976, the drive shaft is not stainless and is more likely to be frozen. It was some years ago and my memory might fool me, but I think you could use the back of the nuts as pullers against the cavitation plate (use suitable spacers).
If it is really stuck, Im sure someone else has a good solution.

(The splines in the joint between crankshaft and vertical driveshaft might be worn down. If so, the motor is running like in neutral. But since the vertical shaft isn't spinning, the water pump isn't working. You can see there is no water coming out from the tell tale.
If you drop the lower unit,(can be difficult) you can see the splines of the shaft are worn, but maybe not totally disappeared. The crankshaft splines seem to give up first.
You might have to repair, or replace both crankshaft and vertical drive shaft.)

good luck
Robert, Sweden "
 
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