FIA-F1

when the temp control is set at full heat and fan running full, the temp guage hovers around mid-level. When fan is off and temp is set lowest cool, the temp runs high bordering on touching the warnng level. I'm hoping a thermostat replacement will be a cheap fix but wanted to ask if that was too much to hope for(?)

sstrickstein

Youve either got a:
1. clogging radiator internally or fins diry and clogged.
2. fans failing.

I would first check if you have a blockage in the radiator. Remove and flush. Take the fans out first as it will be easier to get out. If youve never replaced the radiator and its original it might need to be replaced.

Grandpa#3

It would help if you put in the year and model of your car so no one has to guess. It might pay to take your car to a radiator shop or call an auto parts store to see if they have a Thermal Tester. The tester can tell you if there is a cold spot in the radiator meaning a suspected blockage in that area. An old radiator hose can be collapsing internally restricting full flow. When did you last change your hoses? I hope it will be something simple for you.

Cheers,
Larry

FIA-F1

Thanks guys, good advice. It's a 1991 944 S2 cab with 86K miles. The radiator has paint overspray on it from previous owner. The overspray is not a light dusting but some heavy coating on about a third of the fins. Could that be be a cause?

Grandpa#3

The radiator fins should NOT have any coating what so ever. The fins are thin so they can cool more readily. Be careful what you use to remove the paint, so make sure it will not harm aluminum.

Cheers,
Larry