Here it is, have a 2001 500efi 178hrs, runs great. However the temp gage very often runs up to 180. It used to run at 145-155 changed thermastat, ran 150 for about 2 hours, then back to 180?

Any Ideas? should I change it again? or do you think the sending unit or gage could be wrong?

Thanks
Will

You do have some kind of problem, either the thermostat or the water circulation. The thermostat is the easiest to check or change. I recommend Mercruiser or Robert Shaw thermostats. If the thermo isn't it, FIND THE WATER RESTRICTION OR PUMP PROBLEM. The engine and the FI don't like the heat and can cause detonation!!!

Thanks

Will

I think you need a water pump rebuild.

My 454 with closed cooling has a 170* t-stat. It runs 170-180 all day long.

Ditto on what Troutly said. 150 +/- 5%

Canada Jeff,

Yes I have a Water pressure gauge, it reads very strong pressure all the time except when idling. My oil temp stays around 150 I think? the oil temp always stays low. I think it is the gauge itself or sending unit?

Will