Overheated?? Probably!! what to check??

[daydreamer1252]

I knew I'd be back. Bought a used boat (didn't pay much) It has a Mercruiser w/GM 4 cyl. Boat is an '83, some confusion about motor, drive says 3.0 and valve cover says 120 don't think that is a valid combo. Engine serial is 6809214.
When bought boat seller said it needed a pump and had a new one already purchased,complete w/housing. I can't imagine how they knew that the lower unit w/pump was out without overheating it.
I am new to I/Os but have years of outboard experience. Am also an experienced auto technician. Unfortunately almost all of that experience has been with imports and have little first hand knowledge of this engine.
On a visual inspection (outside of block) there shows no discoloration or flaking of the paint on the head or block.
What should I be aware of and be watching for with this engine? Is a head gasket a necessity/valid precaution? Is the head likely warped? (imported cars would be) Any other things that are usually damaged in this unit with overheating?

As always your insights and experience are invaluable.

Thanks

 

[Haut Medoc]

Re: Overheated?? Probably!! what to check??

If the water pump housing was melted from overheat, check the water pocet cover in the upper part of the exhaust cavity for signs of melting.....
If it appears OK, I would put the pump in & run it...
Disassembly is a waste of time for the engine until you know there is something wrong.....​

 

[daydreamer1252]

Re: Overheated?? Probably!! what to check??

Haut Medoc Thanks again for your reply. NO signs of anything melted. I will just attend to the immediate issues and see if anything turns up later.

 

[ziggy]

Re: Overheated?? Probably!! what to check??

I can't imagine how they knew that the lower unit w/pump was out without overheating it.

maybe, because it's supposed to be yearly pm.
yer serial number falls at the very end of service manual #3 for a 120R.....