Asked by Nov 24, 2010 at 03:26 PM about the 1998 Pontiac Grand Prix 2 Dr GTP Supercharged Coupe

Question type: Maintenance & Repair

I've changed the water pump, thermostat, radiator, and the radiator cap and the car still overheats because water is boiling out of the reservoir is this because my head gaskets are blown? there's no water in my oil and i changed my spark plugs and there was no oarnge film on the old ones.  

8 Answers


the only thing I could guess is that there could be a restriction somewhere in the system, causing an increase in the pressure allowing the radiator cap to release coolant into the reservoir. did you check to make sure the radiator and heater hoses are not pinched or kinked. One of the radiator hose has a spring inside to prevent the hose from collapsing, so it is also possible that the hose with that spring might be bad. cooling system flush may help

3 of 3 people found this helpful.

Danny, I am somewhat using your advice to fix my overheating problem. We literally stripped everything down and replaced it in all to still overheat. I'm wondering if you have a suggestion as to where the restriction might be because it is not with the spring issue. My original post is on the Sebring forum. Thanks for your help!

2 of 2 people found this helpful.

the other things I would consider checking verify that the radiator cap is the correct pressure rating for your car correct coolant/water mixture it may not be a bad idea to check to see if the engine coolant temperature sensor is working correctly missing, loose, damage deflector and/or seals that maybe used for a radiator and/or any add on accessories that could block air flow to radiator whether the cooling fan motor is getting power and that they are work and the blades are not damaged

1 of 1 people found this helpful.

you could have a cracked head that leaks exhaust into the coolant and builds pressure,you won't see any oil .

3 of 3 people found this helpful.


1 of 1 people found this helpful.

did you bleed the air pockets out of the cooling system?

4 of 4 people found this helpful.

If you havent yet change the plastic coolant elbows under the supercharger and alternator. could be cracked and leaking causing issues. $3 at autozone and orielly auto

2 of 2 people found this helpful.

air air air there is air in your system I guarantee it I have a 2001 Grand Prix GT coupe I'm going through the same problem right now I replace the head gasket set radiator the hoses the heater core the water pump everything and the air is still making my engine overheat like crazy and other times it doesn't overheat there is air and its a pain in the ass to get Out. there is a bleeder valve on top of your thermostat housing but it takes a lot of times to get it out good luck

1 of 1 people found this helpful.

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