97 Cavalier 2.2 Overheating

[Curn]

Update:

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?

[Quick273]

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.

[ChemMan]

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.

[Quick273]

As much as it pains me to say this, I do silly things like that also . 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.

[test5588]

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

[mike432]

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.