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 diana408004 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.

24 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.

28 people found this 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.

6 people found this 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.

19 people found this helpful.

You have air in the coolant system.

13 people found this helpful.

bleed the coolimg system to get the air pockets out

9 people found this 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.

5 people found this helpful.

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 people found this 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.

3 people found this 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

2 people found this helpful.

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

7 people found this 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

3 people found this 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

12 people found this 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.

4 people found this 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!

20 people found this helpful.

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

2 people found this 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

1 people found this helpful.

So, you haven't had heat for a month? None on any setting? What is your coolant level? Do you have coolant in overflow tank or radiator (should be in both)? Come on! Give us more info! I'm going to assume you checked levels. Overheating is usually do to, low fluid, bad pump, bad thermostat, plugged radiator, fans not running properly, air pocket and whatever else I'm forgetting. With your information, I would say low fluid. Heater can't put out heat with no fluid and car overheats with low or no fluid. You gotta give us more info....


For this of you who have changed coolant and then have overheating issues, you have most likely a air pocket. Let engine cool. Remove thermostat and housing unit. Pour coolant directly into thermostat opening until it's full. Turn car engine over out let run for a FEW seconds. Did engine suck coolant into engine? If yes, pour in more coolant and repeat until no more coolant is accepted by engine. Replace thermostat and housing. Top off radiator. Reconnect hose to thermostat housing. Hold house up and pour in coolant. Pinch end closed (best you can) that goes to radiator. Quickly put hose on radiator losing as little coolant as possible. If need be, top off radiator again. Now turn on engine leaving radiator cap off. Let car run until it heats up keeping an eye on radiator coolant level. Add coolant as needed. At some point, fans should turn on and thermostat should open. Leave car running and let coolant cycle allowing bubbles to escape engine. Fan and thermostat should shut off and on a couple times when engine had reached optimum temp. If thermostat gauge rises and lowers after fans kick on, you should be good to go. Be sure radiator is full and put on cap. Now let it cycle a few more times. You should hear fan kick off and on and see gauge temp go up and down. Now be sure overflow tank is full to level marked "hot full." Now let engine cool down completely. Check overflow tank to see if motor sucked coolant back in motor as it cooled. If it has, that's a good sign. Now check again to see if radiator is still full. Top off if needed but it should be full. Now take your car for a drive until car is completely hot and cycling. There should be no change in temp while turning turning corners. Over the next few times you drive and park, keep check overflow tank levels when it's hot and cold. Good luck!

1 people found this helpful.

So, you haven't had heat for a month? None on any setting? What is your coolant level? Do you have coolant in overflow tank or radiator (should be in both)? Come on! Give us more info! I'm going to assume you checked levels. Overheating is usually do to, low fluid, bad pump, bad thermostat, plugged radiator, fans not running properly, air pocket and whatever else I'm forgetting. With your information, I would say low fluid. Heater can't put out heat with no fluid and car overheats with low or no fluid. You gotta give us more info....

I don't have a answer to this question but I'm stressed that my car isn't working properly. I was on the interstate and doing 70 and my light came on to check gages it was my temperature gage. So I pull over and I have no water which I checked and topped off the week before. I had no problems at all till this day. Anyways I filled and watched the temperature gage the whole 45 minutes it took me to reach my destination at that point the temperature gage went up and down hotter at some points if I gave it has it would cool down if I turned air on it would get hot if I slowed down and took my foot off the gas it would heat up. So I reach my destination and check it again and no water. But no leak. The oil is fine. Where my a.c. normally leaks is a leak but nothing else anywhere. So I tested the theory I filled it up with coolant and let my car run for about 20 minutes. Watching looking for a leak but nothing. But coolant is gone from resovor so not sure what to do or how to fix. I bought water pump and new belt and I haven't put it on yet because every one I have spoken to says if it was the pump that there would be a viable leak and there isn't one. So please someone help

Ok I have replaced the radiator - thermostat - coolant fans. Topped off coolant still says add coolant and temp gets to 210 then car shuts off Ideas????

Snyderfields, same here. Have you resolved the issue yet?


I am having the same issue. I have a 2008 pontiac grand prix with 172,000 miles. Changed the water pump, thermostat, had air bled from system and also had radiator flushed. Brought it to a mechanic who said that its the head gaskets and valves and wants $1750 for the job. Said I would think it over. Took it to work today and now the gauge stays right by the red regardless if air or heat is on. Wondering what to do.

5 people found this helpful.

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