I have a 2002 grand am se and it keeps over heating it use to take a while but now its over heat after about 10min driving. I replaced the water pump gasket and bypass hose. I'm thinking its the therm
You may need a new radiator. Replacing the thermostat is a good idea and while you are at it flush the engine and radiator and install a good coolant and add Redline Water Wetter. Check to make sure your cooling fans are coming on when the car gets hot.
Typically I would suspect the temp sensor on the engine which happens on Grand Ams after they get old, but if it heats up after only 10 minutes and you have no engine light coming on then you desperately need to change the cap on your overflow. The cap on your overflow is set at 15 pounds but as it gets old it does not hold at 15 and unfortunately the 2002 Grand Am is sensitive and will raise temp quickly when pressure in the overflow fails. Make sure your overflow is not over are under filled and change the cap. When temp sensors fail or get worn the temp usually takes more than 10 minutes or you start seeing different things not described here.
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