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97 Cavalier 2.2 Overheating

10-06-2006, 12:55 PM
I am having overheating problems with my car, I had the car in the shop where they replaced the headgasket, got the head machined, got the radiator rodded out, checked the water pump, replaced the thermostat tried three different ones. The only way they could get it to run without overheating after doing all of this was to run it without a thermostat. I ran it that way for a couple of months, but it is getting colder where I live so I put a new thermostat back in it, now I am having the same problems, it runs somewhat OK while driving, it does not heat up right away maybe after 30 mins or so at city speeds, however at lower speeds it starts to heat up. If i put it in neutral and increase the RPM's the temp gauge will drop down. After stopping I can feel the hose coming out of the thermostat housing to the radiator and the hose is cool, so for whatever reason the thermostat is not opening, I drilled an 1/8" hole in the thermostat to let any air through that may be in the system. When I refilled the system I opened the bleeder screw that is above the exhaust manifold until antifreeze came out of it then I closed it and filled the rest of the way. Any suggestions?????

10-06-2006, 06:06 PM
sounds like the thermostats the problem, having 4 bad thermostats is pretty weird, but not impossible, have you ever tried testing one before putting it in??

10-06-2006, 06:36 PM
No, are you talking about putting it in boiling water to see if it opens?

10-06-2006, 07:38 PM

12-11-2006, 01:02 PM
I have a friend with a 98 Sunfire with the same exact symtoms. It shows no sign of a head gasket leak or a cracked head. Yet it still overheats constantly. Ive been through 4 thermostats, several size bleed holes and no success. I was wondering if you ever solved your problem?

12-12-2006, 04:51 PM
you can always try just removing the thermostat, if that fixes the problem, then you know its the thermostat(s)

Current Resident
12-15-2006, 09:54 PM
:shakehead Actually if replacing the head gasket as you said and the thermostat and it still overheats the very next thing to check is the heater core if it is plugged or even partially plugged will cause overheating and no circulation through the radiator.
The reason for this is if you look at the way coolant circulates in the 2.2 liter engine from 1995 until the echo-tec the thermostat is in the lower radiator hose fitting on the block that is the cold water inlet from the radiator coolant is pumped through the heater core and returns to the engine just behind the thermostat and back into the engine when the coolant returning to the engine from the heater core gets hot enough the thermostat opens and lets coolant in from the radiator.
You can bypass the heater with a piece of heater hose to check it out.

12-18-2006, 08:39 AM
Could you explain how to test or bypass the heater core? I'm having this exact same problem.

also, where is the best spot to bleed the cooling system to ensure no air pockets are there?

12-18-2006, 11:27 AM
scratch that previous post, I need a manual to replace the water pump

12-18-2006, 06:50 PM
if you can't tell, I'm in a little bit of trouble.. and a lotta bit frustrated!

the cooling fan of my '92 2.2L doesn't turn on when it is supposed to. I unplugged the wire that runs to the thermostat, and the fan runs constantly like it should. After running for a very short period, the check engine light came on, probably telling me about the missing themostat. So ECM is fine, relay is fine.

What is the temperature switch? does my model even have one? where?

What and where is the thermostat sending unit? could this be whats wrong?

please help! what is wrong with my car?

--I've already replaced the radiator because of a leak, the water pump because it went out due to the leak, and the fan relay, trying to fix the fan!

I should add that the temperature gauge on the dash works when the wire is plugged into the thermostat

06-01-2007, 11:21 PM
I have a 97 Cavalier 2.2 and I have a very similar problem that has stumped 5 different mechanics in the city where I live.

It started with the car overheating (not into the red but very high normal) then the head gasket blew out, got the gasket replaced and the head checked for warps/cracks and there were none. The car still overheated after the new gasket, so they replaced my radiator, thermostat, water pump and in the process bleed the cooling system like 5 times! The car doesn't always overheat, it seems almost random... and when it does overheat, if I slam the gas pedal to the floor (usually in anger over my POS car not working right) the temp comes back down to mid normal... I'm baffled.

Have not checked the heater core, I'll get that done this week.

Any more ideas?



06-02-2007, 06:46 AM
checking the heater core would be a good idea. Don't forget to check the radiator fan, is it coming on? Just a couple more ideas:

is the temperature sending unit okay? This is what provides data to the ECU about the temperature of the coolant. This screws into the thermostat housing and has a wire running to it. This could result in the temp gauge on your dash jumping around, and if your ECU doesn't think its hot, it won't turn on the radiator fan.

if your fan still doesn't come on, test it manually by unplugging the wire that runs to the temperature sending unit. The car goes into "oh shit mode" and just runs the radiator fan constantly.

Seems obvious, but are you losing coolant? A leak (pressure loss) could cause this. Check all hoses and connections.

other than all of that, I guess it could also be your dash gauges, or the electrical system in your car! :banghead:

Good luck and god be with you man, I never fixed this problem. (own a different car now) Then again, I never checked the heater core because I was too lazy to rip the dash apart. Update me with how it goes! I'd like to know the solution I couldn't ever find.

oh one more thing, now that I re-read your post. When you stomp the gas, the gauge comes back down? So is your serpentine (spelling?) belt tight? Maybe the tensioner is bad, belt is slipping, and the water pump isn't pumping. Stomping the gas makes it spin like hell, and it works, but at low rpm it just isn't enough. So make sure this is tight and fits within specs.

06-02-2007, 07:40 AM
The fan is coming on, and doesn't seem weak, it seems like it's coming on at the right time.
I'm not leaking any coolant anywhere that I can find.
It's not burning coolant (cracked block)
It's not leaking coolant into the base (typically cracked head)
Serpentine belt is new, is put on the right way, and is tight. Just went out and checked the tensioner, seems fine. :banghead::crying:

I guess I'll replace the heater core... I also read last night that a bad EGR can cause overheating... I dunno.

All I know is that I've spent $1800 on a POS that's not worth it, and I can't afford to buy a new car... so I have to fix this one... or burn the POS... I have full coverage :devilsign:

06-02-2007, 08:05 AM
before you go and replace it, try to bypass the heater core. if you get under the car, in the back of the engine bay you can see the hoses running to the firewall. if I remember correctly, they are really easy to get to. take one off and loop the other back to where the first plugged into the engine.

if that fixes it, and you don't mind not having heat, then you're good to go!

06-02-2007, 08:13 AM
as far as the EGR valve:

Definition: The EGR valve is the main emissions control component in the exhaust gas recirculation system. The valve is located on the intake manifold, and opens a small passageway between the exhaust and intake manifold to allow a metered amount of exhaust to flow back into the engine. This reduces combustion temperatures and helps control the formation of oxides of nitrogen. The EGR valve is opened by the application of vacuum to its control diaphragm. Some also require a certain amount of exhaust back pressure before they'll open. On newer vehicles, the valve is electronic and uses one or more solenoids or a small stepper motor. The valve should remain closed while the engine is cold and at idle. It should only open once the engine has warmed up and is running at part-throttle. If the valve sticks shut (or is disconnected), NOX emissions will soar and detonation will often result (See Detonation and Spark Knock). If it sticks in the open position or fails to close all the way, it acts like a vacuum leak resulting in a rough idle, hesitation and possible stalling.

you haven't mentioned either of those, and I don't think my cavalier had those problems, but who knows? I don't know more than the next guy.

06-22-2007, 11:21 AM

Car still shows that it is overheating, but I don't know if it really is, we checked it with one of those laser temperature readers and it doesn't seem to be as hot as it reads on the gauge.

The car is getting HORRIBLE fuel economy. My question is can a sensor like the O2 sensor or the air-flow sensor caue the car to run lean/rich and cause overheating?

07-28-2007, 04:37 AM
As much as I hate to say it, it's nice to know that I'm not the only one with this problem. I just recently purchased my '97 Cav with 150k miles on it and other than the "overheating" problem, it seems to run fine.
So far, I've tried 2 thermastats, water pump, and chemical flush/fill. All to no avail. I've checked all hoses and found no leaks. The test for a blown head gasket came back negative. Running without the heater core is not an option according to my wife, so I'm stuck there. If I didn't know better, I'd swear this car is going through menopause with all the hot flashes. Any other ideas would be welcomed.

07-29-2007, 05:55 PM
Just as a quick idiot check, make sure the thermostat is facing the correct direction. The sprung end should face the engine, and the end with the brace should face the radiator hose. No offense to anyone, but I know I do stupid stuff like that on occasion.:banghead:

08-01-2007, 03:00 AM
As much as it pains me to say this, I do silly things like that also:screwy: . I bypassed the heater coil and tested again. Wouldn't ya know it, it still tried to overheat. Oh well. Finally got tired of fighting with the car and removed the thermostat. Yes, it was installed correctly. Was thinking to myself as I loosened the bolts, "I'm gonna laugh if I installed this silly thing wrong". Now it's running at the low side of the "normal" range. I'd really like to figure out the real problem so when winter hits, my wife and I dont freeze our butts off going to work.

04-03-2011, 10:31 AM
I own a 97 cavalier aswell. 2.2 and same problem. heres what i have figured out so far from all the reading and testing. if i jump power to the fan it works. k so fan is good. voltage is good to the cooling sensor and the relay. i did however read that the designer of the vehicle is an idiot. he placed the computer in a real crap spot that gets hosed alot. if your in a state that has alot of salt during winter then you should look and see if their is corrosion on the cover's seal of your box. or at the connectors to the computer. one person used diolextric greese on the connectors and all worked out real good. im not at that point yet. im gonna back trace all the wires just to make sure its not something simple as a bad connection or bad ground. ill post again as soon as i fixed my car. either with brains, a wrench or a bullet it will get done :)

11-13-2012, 10:11 AM
I was having problems with my car overheating. I did a coolant flush and thought that fixed it but the problem came back. The pump developed a leak so I changed that and it seemed to not overheat for a while but the problem came back. I changed the thermostat and that did not fix the problem so I did some more serious research and testing. I noticed that the radiator fan was not running when the engine was going into over temp so I hotwired it and found that the fan was good. I hotwired the relay and it clicked/the fan turned on so I know the relay is good, I also tried different relays. I tested the temperature sensor with an ohm meter and was getting normal readings while in the cold and hot states. I ohmed the wires going from the temp sensor to the computer and they checked out fine. I ohmed the wires from the computer to the relay and they were fine. Then I started the car and let it get above normal operating temperature, I had the relay out and was measuring voltage to see if the computer was supplying a signal to turn on the relay. What I found is that the computer was supplying 12 volts to the relay but it did not have enough current to activate the relay. So now I believe that the computer is bad or a connection to the computer is bad. I have recently noticed that it only overheats when at idle and if I give it a little gas while at a stop the temp will go back to normal. When on the highway the temperature stays low and will not reach a normal operating temperature. One day while on the highway and the engine was running cool I heard a pop, it sounded like a balloon. I think it was the catalytic converter and now my oil pressure light comes on at low RPMs. I think what’s happening is the computer is not controlling the fuel air mixture properly and at higher RPMs runs rich and at lower RPMs runs lean. I was not able to locate in a schematic where the computer gets its power and ground connections, it is not grounded to the frame.

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