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Junk or not?

J

Jesse1985

New member
I have recently bought a 1979 40 hp Mercury Thunderbolt 5174089 that is peeing slow and has water in the motor pan. Seems to be running fine. It has been recommended to just change the impeller, but should there be any water in the pan? Sorry I am new to boat motors!
Thanks for any help!
 
I would take a rag and dry up the lower cowl pan, fire up the engine (on a flusher or in a improvised tank) and see if you can spot where the water is coming from.

There could be a few sources other than the ones noted above. Once you track down what is leaking, and it's probably a poppet or cover gasket or even a base gasket, you know what needs attention.

These were decent motors and it really isn't "that old" - certainly worth fixing up if it's something as simple as a gasket or seal.
 
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