overheating, where to start

[james_r_]

I have a mercruiser 260 (Chevy 350 to me) and this 4th we experienced an overheating problem.<br />After running fine all day (4 hours) we stopped anchored, then restarted the engine just to keep the battery charged. After 2 or 3 min I noticed the temp gauge at 220 (pegged)Didn't manually shut down immediatly. Tapped the gauge ,listened<br />then shut it down. There wasn't any noise prior but when it shut down ,sound like popping or a <br />very small amount of water boiling. This was loud enough to hear through the engine cover<br />But in contex I was listening for any sound<br />that would compare to a overheating car engine(knocking,siezing,belts squealing) <br />So, please help <br />Idle speed, no engine noises (running)<br />sounds like boiling water after shutdown?<br />Where do I start????<br />Thank you for your reply

 

[Bondo]

Re: overheating, where to start

T-stat...<br />Impeller...<br />Restriction...

 

[Ralph 123]

Re: overheating, where to start

Then check this out:<br /><br /> Good exhaust is a MUST

 

[TedCT]

Re: overheating, where to start

I have the same motor and am experiencing overheating at higher rpms. Above 1/2 throttle she heats up quick, but I've come off the throttle in time not to overheat her. Anyway, I am going with new risers as my next attempt at fixing. Changed water pump on engine, outdrive is only 1 season old. I opened the riser drains again and got more rust which tells me what...they are rusted. Apparently clean risers are important, I'm changing them and will let you know how I make out. If your outdrive pump/impeller have not been changed in two years, change them. If the pump on the motor has not been changed in 3 years, change it. Open the riser drains, if rust comes out, change them. Inspect the manifolds with riser off as best possible. All of the above fixes are relatively cheap compared to a new engine.