Ok, so I have a 1997 Pontiac Sunfire. It was overheating so I took it to the shop and they ended up changing the thermostat. It has been a week or two. Today it was about 50 degrees F out and it started to overheat pretty quickly. No steam, just hot lines. There is plenty of coolant in there as well. Any ideas?
Why does my Sunfire overheat after replacing the thermostat?
Story first, recommendations after:
My friend had the same car except the Chevy version (Cav, same car, different body)... I think there is something wrong with these things re: cooling. His was overheating so he got the thermostat replaced, didn't do anything. Then he replaced the pump so it started blowing out coolant through the overflow... he wound up carrying two coolant bottles with him wherever he went and the whole car always smelled sweet (glycol based coolant)
Also eventually the coolant ate through the conveniently located cables under (through?) the coolant system and his left (I think) light stopped working (his fog lights were still ok)
Other than that the car was great... I think it just has some serious design flaws as far as the cooling system goes, so you might be kind of unlucky...
But to go through a checklist:
check if the fan turns on if the engine gets hot (let it idle for a while), this I believe is controlled via a different thermostat
check if there is any obstructions in front/behind the radiator
make sure your oil is nice and changed every 3000 miles (synth/semisynth... don't run anything else and don't listen to the 5/10k thing esp if your engine is running HOT, also make sure you swap the filter every time)
make sure you're running the right coolant for your car (check manual)
make sure you don't have too much coolant (this may mess with your thermostat)
if all else fails you can start ripping out the grille (I think it has some plastic parts) and the insulation on the hood (this may or may not help, and it may actually hurt you if there is a lot of sun...)
finally you might want to unplug the thermostat altogether... but it will trip the ECU warnings... read more in the attached thread... seems lots of these have this problem
Why does my Sunfire overheat after replacing the thermostat?
check to see if your fan is turning on
Then the thermostat was not the problem. Though I have seen false over heating if they did not get all the air out of the colling system.
Otherwise, the rad could be clogged or the water pump is bad.
