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3 1/2 HP Mercury Lower unit

circle hook

circle hook

Regular Contributor
Hello I have a 3 1/2 HP mercury and I think the drive shaft is stuck in the crankshaft, any ideas on how to free this without beating and braking the alummium lower housing.
I alao can not seem to be able to find the year of this engine it has a netural shift lever but no opening to disconnect it and I also can not lower it either.
3 1/2 HP Mercury
SERIAL# 6336982

Thanks Bob
 
Can give you the year - it's a 1983.

Never seen one, not covered in my service manual collection (which tells me this was probably "made for Merc, not made BY Merc)).

Having said that, a stuck drive shaft is universally a royal pain in the butt.

This being a very small motor I would be inclined to undo all the bolts holding down the power head and try and remove it that way - possibly less chance of damaging something.

If you can even get the lower unit down "a crack" then maybe stand the motor upside down, get the (straw) from a can of penetrating oil into near where the drive shaft is and just unload the can - leave it standing on it's head and hope that the oil works it's way down to the (joint) - leave it like that for a day or two and see if she loosens up.

If that don't work, I would try pulling the powerhead - you will toast the base gasket, probably the exhaust gasket, but better than cracking the cav plate or lower unit...
 
thanks I will try that and thanks for the year 1983, one last question is how do you disconnect the shift rod there is no opening on the side with a rubber cap or the lower unit does not come down, I cant find a schematic so I have no idea on how to disconnect it.

Thanks Bob
 
circle hook said:
t I cant find a schematic so I have no idea on how to disconnect it.
Click to expand...

Me either :(

Like I said, my collection of Merc service manuals does not include this model and most of the "on-line" diagrams from Merc are gone now - some new format.

Sorry
 
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