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.

15 Answers

40,345

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.
50

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.
535

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.
120

You have air in the coolant system.

8 out of 8 people think this is helpful.
2,715

bleed the coolimg system to get the air pockets out

4 out of 4 people think this is helpful.
1,175

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.

535

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.
120

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.
45

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

20

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.
20

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.
70

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

7 out of 7 people think this is helpful.
10

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.
80

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!

7 out of 7 people think this is helpful.
80

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

1 out of 1 people think this is helpful.

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