Overheating Question

[HPBoats83]

I ran my boat in the ocean and it ran strong at ~150*, I pulled into the marina and after about 2 minutes at idle, the temp started to climb to ~190* as I was putting it on the trailer. After that I changed the impeller, housing, shim, and O-ring and flushed out the oil cooler, that didn't help. The boat still runs solid 150* while I'm running the boat but after about 2 minutes at idle, it starts to heat up.

I can bring the temp down by putting the boat in neutral and revving the engine to about 1,500 RPM which shows about 5psi on my water PSI gauge, then my engine temp will drop back down to about 150 AND STAY THERE while idleing.

Don't think it matters, but the boat is a 29 Fountain with a 500EFI.

 

[MOBILEMERCMAN]

Typically when "you fast idle it cools" is a lack of flow problem. When the temp creeps up at idle also could be a lack of flow problem or stat stinking. When you fast idle it it cools and STAYS also makes me think thermostat stinking. Just for grins make sure air isn't entering a flush attachment.

Bravos in salt after 5 or 7 years may have a water restriction problem where the intake hose goes thru the transom. 23 lbs at 5000 rpm is the spec for early motors.

My long distance assistance attempt.

 

[HPBoats83]

Thanks for the tips, I will see what I can find.