What cause overheating on a 1999 grand am
5 Answers
Do you have to add coolant often? If you do then you obviously have a leak. First (and most obvious) is the radiator cap ... it's essential the radiator holds pressure (8 to 15 lbs PSI) or the coolant will boil ..Second .. That engines thermostat can leak and you may never see it because it's located under the engine ... check there for evidence of a leak
No leaks it's like it keeps getting air in the coolant system
The coolant is at about 5 pounds above the outside air pressure ... wouldn't it seem reasonable for the coolant to leak out before air can get in? A friend had a 99 Pontiac Grand Am Quad 4 and had the same "mystery leak" ... it was found to be the thermostat cover that's under the engine .. but they found it after the engine got so hot that it seized ,,