car over heating, have changed water pump, thermostat, and radiator. will heat up to 240 and drop to 220, when you go around a curve it will drop to 180 and go back up to 220, what else could be causing this

Asked by Aug 08, 2007 at 08:40 PM about the 1995 Pontiac Grand Prix

Question type: Maintenance & Repair

What could be causing my car to overheat? I have changed the water pump, the thermostat, and the radiator.

16 Answers


These vehicles were known for blowing head gaskets. It sounds as though you may have this problem. Have the cooling system pressure tested to see if there are any internal leaks which could be causing overheating. Also, it is possible that you have an air bubble in the cooling system which is causing the system to overheat. Try running the engine with the radiator cap off until it heats up and the thermostat opens, then top off the coolant as necessary. Be careful when working with hot coolant. You may also have a defective coolant temperature sensing unit which is causing false readings as you corner, etc.

17 out of 17 people think this is helpful.

When I got my car I found that my computer was slightly fried and one of my fans was out and it did the same thing as your car was doing so you may need to check the computer that hooks to your fans. I think it costs around 300 dollars to get a new one unless you find a used one that goes with you vin # which I really had a hard time finding.

2 out of 2 people think this is helpful.

I have seen this problem before. it ended up being the radiator hose was sucking its self closed and causing the car to over heat. check the bottom radiator hose it is more then likely very soft.

11 out of 11 people think this is helpful.

You have air in the coolant system.

8 out of 8 people think this is helpful.

bleed the coolimg system to get the air pockets out

4 out of 4 people think this is helpful.

If the temp changes drastically on turns i would actually say you may have a wiring issue or a gauge issue. I wouldnt think that a head gasket or air in the cooling system would cause the temp to drop on turns. I cant see the gauge giving you accurate readings the way you describe it. Good luck.


For some reason when you turn and the coolant moves from one side of the vehicle to the other the lower radiator hose will suck its self closed and it will no longer allow coolant to pass through the hose. I have seen this on many GM vehicles. try new radiator hoses yours are most likely very soft.

3 out of 3 people think this is helpful.

Radiator system is a high pressure system. Hoses burst outward when they are old and weak. You need to bleed the air out of the system.

2 out of 2 people think this is helpful.

be sure when you buy new radiator hoses to buy the ones with the coils in them to prevent this from happening in the future


im having the same problem. Keep having to bleed the air out of the system. Still can not figure out the problem

2 out of 2 people think this is helpful.

I was having some of the same overheating problems after replacing the radiator until I read some of the posts here on the page and discovered that I had not burped the cooling system, After doing so the temps went to normal and I ran the car for over an hour with the temp maintaining at around 190 degrees. Thanks for the help Mario

2 out of 2 people think this is helpful.

I changed the radiator thermostat change the water pump car still overheating above the system losing water somewhere could it be a hose or do you think its the head gasket

8 out of 8 people think this is helpful.

For those of you that have GM V-6's the overheating can be caused by faulty lower intake manifold gaskets. GM used plastic and rubber on these engines and after a while the plastic gets brittle and breaks allowing coolant to go into the engine. This is not nearly as severe as a blown head gasket, but it's not easy or cheap to change. I have done it in around 12 hours using new Fel-Pro gaskets.

1 out of 1 people think this is helpful.

12 hours? I did the intake manifold on my 90 olds 98 with the 3800. Took about 5 hours my first time. And any coolant going into your engine is bad news. For one, water (and/or coolant) doesn't compress like air, and can and will cause warped heads, cracked heads, blown gasket, etc. But to people still looking at this for advice, check the oil, does it look like chocolate milk? If not, the check the coolant, it should just be orange for this car, so if you see any brown or actually see oil, or answered yes to the first question then it's either blown head gasket or cracked head. If it isn't those things then don't worry because that's the most expensive thing to fix. An intake gasket can run you between $60- 160 depending on where you're at and the store (just saying). Probably close to $600 at a shop. I would start with the cheapest thing first, bleed the cooling system adding water/coolant as needed (also, while you're bleeding it, if you noticed the bubbles aren't going away, that means air is getting into the system somehow and is usually head related). You should also try to flush out the cooling system. Then go to the thermostat, simplest way is to start the car til it's hot and grab the upper radiator hose (should probably wear gloves)and you should feel water moving through it. If you dont, I would take the thermostat out, boil some water and drop it in. If it doesn't open in boiling water, then you know it's bad. If it isn't that, then go to the hoses, do they feel soft or easy to crush with your hand? Then change those as needed. Now, check the water pump if you know the thermostat is good, but couldn't feel water coming through. And make sure to take off your belt and grab the water pump pulley and wiggle it to see if there's any play in the bearing, such as if it moves side to side or if you can twist it (not turn or spin it like it should). If none of that has fixed your problem, then try the fans, these cars typically have dual electric fans so you should check it multiple ways. First, find the connectors to the fans and there should just be a positive and negative wire leading to the actual fan, hook up some wires to give those fans some juice, and if they don't come on then it's the fan. Next, you should start the car til warm, and if the fans don't come on then, but they did when you directly powered them, it's something with the relay or computer to the fans. Try switching the relay with another temporarily and see if it works then, if not it's the computer. And finally, if none of these things have worked... Either spend some money at the shop or getting a new car. Hope this helps anyone with overheating issues!

11 out of 11 people think this is helpful.

I say all of this assuming your car isn't leaking anything.

1 out of 1 people think this is helpful.

my heat stop working a month ago for one day on the way to work i moved to ohio from nc which is a colder climate than usual anyway i went to goto work this morning and it over heated on me I'm trying to figure out why i looked at the oil and it looks normal so i assume that the head gasket is fine what should i check first

Your Answer

Add photo

Related Questions

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 2,855 nationwide Grand Prix listings starting at $1,595.


Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Reputation 4,070
#2 Tom Demyan
Tom Demyan
Reputation 2,720
#3 munron
Reputation 2,110
View All

Related Models For Sale

Used Chevrolet Impala
566 Great Deals out of 28,668 listings starting at $1,595
Used Pontiac Bonneville
3 Great Deals out of 535 listings starting at $1,695
Used Chevrolet Monte Carlo
8 Great Deals out of 1,409 listings starting at $2,500
Used Pontiac Grand Am
1,272 listings starting at $799
Used Chevrolet Camaro
132 Great Deals out of 35,283 listings starting at $1,995
Used Ford Mustang
320 Great Deals out of 45,522 listings starting at $2,000
Used Nissan Maxima
266 Great Deals out of 25,822 listings starting at $2,545
Used Pontiac Firebird
7 Great Deals out of 789 listings starting at $1,800
Used Nissan Altima
776 Great Deals out of 76,998 listings starting at $470

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
10 Great Deals out of 430 listings starting at $2,495
2007 Pontiac Grand Prix For Sale
4 Great Deals out of 411 listings starting at $1,595
2006 Pontiac Grand Prix For Sale
3 Great Deals out of 440 listings starting at $1,999
2005 Pontiac Grand Prix For Sale
342 listings starting at $2,999