Sorry about the question thats kind of off-topic but I dont really want to sign up at a boat forum. My problem is that I have a 1987 starcraft i/o 4.3l omc v6 and when it sits it runs at 205 ish no matter what idle rpm and when you are moving at a good pace it runs at 160 ish (normal). Here is what I have done so far: replaced thermostat (160 degree) replaced impeller, flushed out system from engine and back, and put on a mechanical temp guage. BTW it ate the new impeller that I put on it in about 15 minutes (chunks were missing it did not melt), so now its back to the old one which looks pretty new anyway. And when it ate the old one it stopped cooling all together (obviously). I just took the hose off of the engine that comes from the outdrive pump and it spirts very little water and air. How would air get into the outdrive pump?? Any help is appreciated. I am really stumped.

 

?

 

water pump if you have one or heat exchanger

 

205 sitting idle isn't too bad, even though it's close for an open cooling system. A higher performance impeller to move more water may be in order, or get a hold of an overdrive pulley for the water pump.