Knucklehead27

whats up guys. i'm new to the forum but not to F-bodies. I have an issue with my 86 IROC. when the car is moving the temp is fine. but when i get stuck in stop and go traffic it begins to over heat. i have noticed the cooling fan does not come on till the car reaches about 255*F. i bought a new sensor for the ECM but i'm having trouble locating it. would anyone happen to know where i could look? thanks in advance.

Stealth_Z28

I believe we concluded the fan temp sensor is just above the water pump, two wires which are yellow and black. Depending on how things go with further testing, I may end up with a problem like yours even though I have already changed my sensor.... (see that other thread)

Knucklehead27

im gonna have to check with my local part store again. i am aware of the 2 sensors above the water pump but neither of the connectors for those match the connector on the new sensor. im gonna do some more digging, ill let you know what i come up with

Stealth_Z28

The auto store probably sold you the one that controls the temp gauge (one terminal?). If you can, take the old one out and bring with you. Be careful pulling those boot covers off the sensors, they have that little lock and can be tight and fragile due to age. I think the one just to the left of the fan temp sensor has something to do with cold idle.

Knucklehead27

if the fan temp sensor is on the right and the left 1 if for cold idle, where is the sensor for the temp gauge? just wondering

Stealth_Z28

The gauge sensor is on the side of the engine, just above exhaust man. I think on driver's side.

Knucklehead27

stealth, do you know what temp the fan is supposed to come on at?

Stealth_Z28

I don't know the exact temperature, my guess would be by 200, I thought
I had come across a link discussing that but I can't find it right now.
Please let me know what you come up with if you solve your problem.

Knucklehead27

below is a post from 3rd gen.org.... i replaced the sensor above the water pump with the same results. my next step will be to get an external temp gauge and see what happens then.

Are we assuming the temps are hot because of what the stock factory temp gauge reads? These gauges on a good day are far from accurate - unless the car is actually bubbling over into the oveflow tank, and making steam - you are not overheating. From the factory, these cars were designed to run hot to help with emissions - stock factory fan setups the fan came on at 220, and it's not uncommon at all to see a 3rd gen car run 240 or even higher in the summer without it actually overheating (since the factory gauges suck). You might try a new gauge sender to see if it makes the gauge read differently (it's between #1 and #3 spark plug, in the driver side head - has one single green wire to it).