Asked by Mar 01, 2013 at 07:42 PM about the 1998 Chevrolet Cavalier

Question type: Maintenance & Repair

I have a 98  Cavalier overheating, i've changed the hose from the firewall to where ever (transports the antifreeze). Also the heat switches back and forth from hot to cold. This car has NOT had a thermostat since I bought it over a year ago and I had no issues. Any suggestions??


16 Answers

yes, have a coolant flush, and inspection of the waterpump, new thermostat (should get one every year anyways) and note the output of the waterpump. if it's not pumpin; you should replace it. by now it's probably weeping out the weep hole at the bottom and the seals are hangin on to their very last. blast the corrosion off of your battery with a garden hose and make sure the ground connections are okay from the negative to the frame and to the engine. not that this has much ado with overheating, just good preventative maintenance.

3 of 3 people found this helpful.

Also pressure test the cooling system. This will uncover any leaks. Including a head gasket failure. Check your ignition timing as well. If it's severely retarded check for a bad knock sensor or, if your car has high mileage, a jumped timing chain. BTW, your car needs a 195°F thermostat all year 'round. Since the thermostat was removed I suspect this has been an ongoing problem. The thermostat only needs replacement if it malfunctions it or if you decide to do it as part of your cooling system servicing (every 5 years or 50,000 miles whichever comes first ). HTH. -Jim

4 of 4 people found this helpful.

If you replaced the hose, did you check the fluid after a few drives? Also make sure the radiator cap is working and it is secured on tight. Just a quick check that may not cost much. If all is well, then look for signs of leaks. Is your motor oil normal color? If it is milky in color you may have a head gasket problem. This my friend if fixed properly will be a bit of change out of the pocket book. If you have a garage you really trust, have them check the system out. And yes you really do need a thermostat. I may clear up a lot of issues.

2 of 2 people found this helpful.

DawnC went on vacation and abandoned us, probably got a BMW 300 series and is vacationing on the peninsula near miami-

2 of 2 people found this helpful.

you're all wrong from 1997 to 2000 3 most GM v6 engines have problems with air in the cooling system which locks up the fluid from circulating through the engine it needs to be bled. trust me I've been through hell with this

2 of 2 people found this helpful.

also look for a bleeder valve on top of your thermostat housing that should let you bleed it but it takes a few times. it's a reeal pain in the ass

2 of 2 people found this helpful.

gswag71: No we are not wrong, we only make suggestions over the internet not being able to look, touch, and feel the problem. We rely on past issues we have encountered and fixed. Yes there is always a possibility there may be an air pocket, and the bleeder valve is just the reason GM put it in the cars. Sometimes the bubble will go away on its own, but leave the fluid low. Reading the question, the hose to the heater connection to the firewall was replaced, yet we were not informed why. Was the radiator drained before removing the hose or did some of the antifreeze/water mix leak out in the hose fix? At times not enough information makes it very hard to be right on in our diagnostic responses, and most of the time there is no feed back from the people seeking help on what the final fix was. That my friend helps us all. I've had GM cars since 1965 through now (3 now), and trust me, I've experienced my share of "hell" finding the problems also, as has a lot of us. Either ease off on your writing style, or take a chill pill my friend.

4 of 4 people found this helpful.

Since the original post is about a year old either the person fixed it or got rid of the car. For the record I've owned an '02 Impala 3.8 and currently own a '00 Grand Prix 3.8. In addition to several other GMs. - Jim


About ready to literally have a nervous breakdown after spending $2000 head gasket set replaced by new radiator hoses heater core water pump you name it it's been done and now it seems like it's worse than ever my fans are coming on my radiator is completely full of coolant. And I have removed my thermostat as a last ditch effort and at times I can literally drive for 3 hours and the temperature stays beautiful and then I can get in it and overheat to the point of stalling within 15 min. The only option left is that I have air in my system which sometimes doesn't let the fluid circulate. But my min fact that's what it is. I am sorry for my response earlier just the way my hair out with his car that I love so much and I can't take it anymore have you ever heard of a problem like this

1 of 1 people found this helpful.

Air not hair...lol

1 of 1 people found this helpful.

There is a tool for sucking the air out of these GM cooling systems. Advance Auto Parts sells it. I've never used it but have been told they sell it. Have you tried a chemical cooling system flush? It's possible that a previous owner put some stop leak stuff in there and now the cooling system passages are blocked. That should have shown up when the head gaskets were done. But you never know. HTH. - Jim

1 of 1 people found this helpful.

The old 40s to early 60s motors would overheat when the main bearings were seizing up and they needed to be replaced during a major overhaul. This is not the issue. Have someone with a heat gun search the engine and see where the hot spots are. I even may be the water pump not working, but it does not sound like it. If you replaced the head gaskets, you should of made sure all the water holes in the gasket lined up. Some companies make generic gasket sets and not all the gaskets have holes for the water jackets. There was a lad here a few years ago that had an issue like yours after changing out the gaskets. He tore down the engine and found several water jackets plugged by the new gasket. Something to look at if nothing works out.

2 of 2 people found this helpful.

thanks for the help folks. I can't wait to go to the shop tomorrow to tell my mechanic all of these possible reasons and let him deny each and every one of them even though I know one of them is probably the reason. So we'll see how that works out haha.,,


one of the most overlooked cooling problems on Cavaliers is the electric cooling fan. There are several sensors that tell it when to come on. This engine runs at 235 degrees. The coolant must be under pressure to maintain that temp. So any leaks such as the plastic coolant reservoir or cap will let the coolant boil before the cooling fan comes on. If you are reading close to the max normal temp, check to see if the fan behind the radiator is on. If it is not running the car will overheat very quickly if left at idle without moving. You can test to see if the fan motor is good by putting 12 volts directly to the light blue wire at the fan motor. If it doesnt come on, its bad.

1 of 1 people found this helpful.

presleyha, honestly you described what my 1996 cavalier does. I will let my car idle for a prolonged period of time, and it overheats. For instance i just stopped today 4-20-16 to help a person who broke down today after just buying his honda accord today. Went to give him a jump as soon as he tried to crank the car over I heard that his starter is terrible worn out. Can hear it grinding when he trys to start it as if its not coming out to turn over the car. Though note to anyone who has a 96 cavalier there is a sensor on top of engine which you can disconnect to trigger the fan behind the radiator to come on as well. I think its time I replace my electric fan as it seems to be the likely case for myself.


If you replaced everything and checked compression test for head gasket. You probably have air in the coolant system. This happened to me after having a thermostat replaced and alot of bucks. Found the fix on youtube. Very easy and temp is perfect now. Also it was a GM dealer who did the non repair. You take off the radiator cap and let run 25 _ 30 minutes. Till the water boils up a little... this will release the air lock and bleed it.; turn on heater to high and blower before hand. Watch a youtube video because it has to be done properly so you don't get burnt. Easy fix. Also works for eradicate idle. Idle surge.

1 of 1 people found this helpful.

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