Hey Scotty, I have a 2001 Pontiac Grand Am SE 3.4L V6 with 84,000 miles on it. I changed the coolant in December last year. Ever since then, I’ve been trying to find the solution to an issue I’ve been having with the car running hot at idle, not overheating, but running hotter than normal. I didn’t change the thermostat when I changed the coolant because I decided to be lazy. When sitting at idle, or in a drive thru for example, the temperature needle rises above normal operating temperature after about a minute or so. Once I turn the heat on, it cools down back to or below operating temperature again. I didn’t notice a problem like this before I had the coolant changed. There is no issue with it running hot when it is normally driving. I’ve bled the cooling system as best as I’ve been able to try and make sure there’s no air pockets in the system causing it, but it continues happening. I have been told it’s either a fault thermostat, a clogged radiator, or early signs of a head gasket starting to go by other mechanics. What do you think?
The thermostat should be replaced in any event if it is more than a few years old. Are your cooling fans turning on when they're supposed to? Have you checked your radiator for clogs? Seeing as how you're talking about a 22-year-old car pretty much anything goes.
On my car specifically the pcm doesn't command the fans on until 226 Fahrenheit (so about 3/4 hot on my car). I’m getting the thermostat tested this weekend and if it’s not faulty, I will remove the radiator and check for clogs (I know how to do that myself), and if it’s not that either I will do a head gasket test (even tho I think that is the most unlikely). I will keep you posted.
The radiator is plugged as the lower rad hose that’s going into the water pump is over 70° cooler than the upper rad hose going into the thermostat assembly. And there is a big cool spot on the radiator right where the hose is. I’m going to try a radiator flush but if that doesn’t fix it then I need a new radiator.
Sounds about right.