overheating 4.3 OMC

[jdogonhood]

My 88' 4.3 L OMC overheats on the water but not with muffs in the driveway...? The impeller looks OK however the lining is not perfectly circular and there is some wear. Is this normal? The thermostat housing looks a little rusty but water flows thru. What is the best way to trouble shoot? Could this be the engine circulation pump? If it stays cool with the hose on then there is no clog right? Please help. Summer is almost over and I have not had one good day on the water with my boat.

 

[Bondo]

Re: overheating 4.3 OMC

The impeller looks OK however the lining is not perfectly circular and there is some wear. Is this normal?

Nope,... Not normal,... Probably the Problem...

 

[jdogonhood]

Re: overheating 4.3 OMC

Ok so just fyi for other readers the liner is oblong on purpose and a new impeller did not solve the problem. Overheated on the lake again today. So whats next? any ideas? Could it be the water pump on the block. Selocs says the impeller pushes all the water from the outdrive. In the driveway it runs super cool. I have the 800 cobra with the chev 4.3. Help fellow OMC peeps.

 

[MRS]

Re: overheating 4.3 OMC

I am changing the impeller and thermastat now. last time out tried to over heat at the lake. Might want to change yours also plus open your manifold drain plus and make sure they are draining if not run a wire through them to get all the grud out.

 

[Randy J]

Re: overheating 4.3 OMC

0911844 # OMC L iner waterpump $12. 86 u need this cant be round