Z28_1991_Camaro

I have a 91 Z28 tpi, I recently swapped my 305 with a rebuilt 350. To the best of my knowledge I replaced every sensor durning the swap. Ive been driving it for a few months now, it idles poorly but i never had any other issues with it until about a week ago it started overheating. I can drive about 5-10 mins before Im hitting the red on the temp gauge.
I noticed one of my cooling fans was not turning on so I replaced the motor only to find that didnt fix the problem. I temporarily put a switch on the one fan now so it stays on all the time and the other fan goes on whenever.
I aslo replaced my thermostat and it had no affect on how hot the car ran.
What would cause the fan to stop working and why is my car over heating?
Also, I rememeber when I used to turn my key forward in the ignition without actually starting the car I could hear my fans turn on but now they dont do that, I cant remember when it stopped doing that though. What controls that? Is it a sensor or the computer or something else?

91 355 z28

well your fan not working is 9 out of ten times a relay or ect (engine coolant temp sensor) but as long as the fan is on it shouldnt over heat.. i would check the coolant level, make sure ur thermostat is working, on the bottom (copper color is the temp it opens at, should be 195, or 180.. boil some water with a thermometer in the pot and using some tongs or somethin hold the stat in the pot it should open at specified temp.. other then that try a flush.. something may be clogged.. maybe water pump took a ****, impeller shaft broken? unlikely but i guess possible if it rusted

Z28_1991_Camaro

I took the thermostat out completely and the running temperature seems to have stabilized. I think it's odd that I had overheating issues with my old thermostat which is only a few months old and the brand new one I just put in.
Why don't my fans turn on anymore when I turn the key forward in the ignition without actually starting my car?

ACKRN07

I have an 84 Autoform Z28 Camaro. It seems to run hot all the time. It doesn't actually overheat but if I am in traffic, I think I can actually feel some hot air coming from the ducts. I don't have a dual fan setup. The thermostat is brand new. I have heard that the 3rd gen design is known for not allowing enough air flow under the nose to get to the engine??

Anyone have similiar problems? Do you think a dual fan set up with maybe a dashboard switch would sovle my problem when I'm in traffic??

I have also noticed that the car starts great "cold". But after running, parking and then re-starting a hot engine, it hesitates. A timing problem perhaps??(my car is 5 speed manual transmission)...thanks in advance for any help/suggestions.

racer J

Out of both of my 3rd gens (88 & 92) neither of them have had an overheating issue because of not enough air getting to the engine. So long as you keep that black plastic air damn on under the car, the design is fine.

Bad thermostats are not uncommon. At least not to me. I went through several in my 88 and then I said to hell with it.