slight overheating..

[Frankiea87]

i have a 88 sea ray sundancer with mercruiser 454 7.4l v8 motor. and alpha drive, anyways when i idle theres no overheating, but i open it up 3500rpm-4000rpm for constant 25-30 min.. the temp gauge creeps up to around 200-210 and the max is 220.. now i believe that is too hot., then i back off the throttle and cruise slow and it cools back down about 195ish.. would it be the impeller or thermostat? or something else? thanks

 

[Bondo]

Re: slight overheating..

Ayuh,... I'd start with the Impeller,+ work up from there.....

It's Always the place to start in an Overheat condition....