Thread: Overheating Grand Prix

I had stripped the bolt holes when taking the water pump back out and had to have the shop tap them to put it back in. The top of the bleeder screw was broken off so they said they had to replace the coolant bar. They said it is not overheating but isnt keeping pressure.

Any ideas what that means?

jeez, I hate to hear you're having this much trouble, I know it can be super frustrating. I have to wonder if the thermostat might be in backwards (I did that once I think) but it sounds more like you have some sort of blockage like you mentioned. but I just can't imagine what that blockage is. another possibility might be that the water pump gave out and is not actually pumping (a longshot might be that the pump froze at some point in the past, and tore up a belt which might explain the turd you found. and now its not pumping and thus causing the overheating.) well whatever it is I hope its not too expensive a fix.

take the spark plugs out and fill up the cooling system then pressure test the cooling system and see if coolant comes out of any of the cylinders, also check to see if you have any water in your oil. that will be a indication of blown head gasket. if its not a blown head gasket then most likely its a heater core leaking or something like that.

So I got the car back from the mechanic. They had to replace the metal coolant rail because of a broken bleeder screw. After it overheated I tried to bleed it and broke the screw off. So I was only bleeding it from one side where the thermostat housing was.

The heater works and the hose and radiator gets hot now, but it still runs hot, although not as bad as it was. It still get to like 240. If I turn the heater on full blast it runs normal temp.

The mechanic told me that it is not really running that temp though. He said he hooked up a machine and it showed about 20 degrees cooler than the guage read. He said I might have a broken gauge. Does that sound right?

I never had problems with it before all this. It used to get to 210 and never go any higher.

I think its plausible, temp senders are not really that accurate in my opinion, and if you had an inaccuracy somewhere, the temp sensor would be my guess. Another possibility would be corrosion in the wire to the temp sensor (I think Chrysler or VW had a problem with this, their coolant temp sensors would leak and get into the wiring harness) anyway if that wire was corroded it would affect the signal sent to the pcm and thus the PCM would reflect an inaccurate temperature reading.