Weird overheat problem

Asked by Jul 02, 2016 at 05:02 AM about the 2002 Pontiac Grand Prix SE

Question type: Maintenance & Repair

I have a 2002 Pontiac grand Prix 3.1 and I just
replaced the thermostat in it yesterday. After doing
so I tried to bleed the air till I thought it seemed
good bit when I start driving I notice my temp gage  
woll start to go up fairly quick the hotter the engine
gets at but when I speed up to where the RPM
gage is between 2 & 3 the temp gage will drop
back down. So if I don't have my foot on the gas at
2000 RPMs it will start to over heat. I tried so many
times to bleed the air each time I stop or before I
leave. I don't understand. Please help. And yes
cooling fans work great. Could it be my fuil pump?

4 Answers


Not related to your fuel pump, just basic overheating, the complete cooling system needs to be checked out Water pump, Radiator, Thermostat. Then you need to check that the overheating has NOT destroyed the engines head gasket(s)

1 of 1 people found this helpful.

Well ivjust replaced the thermostat yesterday and I bled the air as much as it would bled and as good as it would go but I been driving it but got to keep the temp gauge at at least 2000 rpms. Well last night I was going home and it got to the red and didn't wanna go down so I pulled over right then and shut it off. Well when I was able to take the radiator cap off it was empty. The caps been leaking for a few days now but not alot at all. And I had a guy look at it and the oil still looks good I don't have water in my tail pipe or nothing and he don't think it's a head gasket. Could it have anything g to do with a bad air flow sensor


A bad/leaky cap and low coolant will contribute to the overheating, you need to stop the leaks like Auto_Centric suggested.

Well I'm glad you said that cause after I got off work at 8 I got out of the parking lot and literally 5 seconds down the road and it's already starting to overheat and not go down now. Well I get stopped and pop open my hood and water is pouring all out from under my radiator cap like it wasn't on good. I even flipped it around and it still did it. And when it finally stopped to where I could take the cap off it still had the water in it. Well I wait for it to cool down a little more and start it back and open up my bleeder valves and the water cone out but it come out like a high powered mist. Not steam but mist and it wasn't that hot so I had someone pick me up and I went and bought a new cap but a better one that has the lock valve on it and it hasn't leaked out of that yet and someone also told me it was the water pump so i got one of those too. but it is still overheating within a few seconds of driving with the new cap but it's not leaking water from that now. So that's a little fix.

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