I have a 1990 Camaro RS V8 305 and it overheats at idle. It drives fine and stays cool on the freeway but waiting in traffic it starts to overheat, I replaced the thermostat but the problem persists. I noticed that the rad fan doesn't switch on, I'm not sure what temperature it's supposed to switch on at but it wasn't switching on, does anyone have any idea what it could be

 

I have had the same problem with my 1989 IROC. Every time i am stopped in traffic, I pop it into neutral which helps the engine to cool down faster. I also replaced the thermostate so that it would let water flow to cool at a lower temperature. You can also try replacing the o2 sensor. I also pop the hood to allow it to cool fater when I get to where I am going.

Hope this helps.

 

Do you have A/C? switch it to on and see if the fan comes on. May be the temp sensor for the computer reading the wrong temp. But if it is cooling while you are moving but not when you are stopped then I say deffinatly check into the fan and make sure it works.

 

the fan is rarely on when on the freeway. the speed alone gives you enough airflow into the radiator. you didnt mention testing your fan motor. plug it directly into the battery and see if it spins. it should. if not, then you need to replace the motor. $40 at autozone. easy fix too. BUT IF NOT....

ive got a 91 RS that currently has the same problem. its not my thermostat or the sensor. i belive it may be a blown fusible link but i wasnt able to find it. there is a fusible link somewhere along the line its just really hard to find. but i was able to get my fan working again with an alternative power source. wut i did was....

1. disconnect the fan motor and put the wires somewhere so that theyre out of the way
2. if you feel the back of the motor, there are 2 little prongs where the fan wires plug in. run a wire directly to the positive post on the battery and another to ground.

that automatically turns the fan on. the only down side to that is that ur fan is going to be running constantly and it will eventually drain your battery. so what i did was install a toggle switch on my dash board and ran the wires through the firewall and up into the back of the dash. so now i operate my fan motor manually. when the temp gets up to about 180 i flip the switch and the fan kicks on. it works perfectly but its just a temporary fix until i find that fusible link. if you need me to explain it a little better let me know. i could also send you some pics if you would like. good luck.

 

Same car same problem. Its most likely one of your temp sensors.

 

make sure you have enough water in it, if it is low on water the fan will not kick on...

 

For sure making sure you have enough coolant is a good idea, but wherever you heard that having low coolant will not allow the fan switch to operate is not correct.

 

Didn't realize someone dug a thread from past....

 

Here's something for you to ponder...the sending unit is reading the temperature of what?
Edit: Oh crap, I just noticed the 3 year old post myself. Gut suckered into that one. lol