Temperature gauge too high on Pontiac Grand Prix?

Question

I drive a 2008 Pontiac Grand Prix. For some reason, the temperature gauge goes up whenever the heater isn't on. If I have the heater on and running hot, then the gauge goes down rather quickly. I had the thermostat swapped out about 3 years ago. If the gauge goes in the high, no steam or smoke comes from the hood, and it doesn't seem hot. Help!

Answer 1

First thing I would try is testing out the cooling fan(s). All you need to do is run jumper wires directly off the battery to test the motors by touching the terminals on the motor. It doesn't matter which way you touch the terminals. It will just affect which way the fan spins. All you're looking for is to see if the fans themselves are good or not. If the fans do work, then try bleeding the cooling system. You might have air pockets in there after the system was opened up for the thermostat swap. If that doesn't work, have the coolant tested for combustion gases as this will determine if you have leaking head gaskets or not.

Answer 2

Called OVERHEATING. Thermostat usually isnt your problem. Thermostat usually fails & sticks open causing a low to no heat from the HVAC system in the winter. Figure out why its overheating. Cooling fan?? Coolant reservior or radiator cap faulty??? Radiator restricted, internal engine issue?

Answer 3

Check your radiator fan is coming on?



The heater can act as an auxiliary radiator and fan if your main one isn't working properly, but obviously this isn't idea.

Answer 4

Hmm