I have an 89 Iroc Z..
305 TPI
700R4
1 core radiator
etcetc.....

I bought the car a week ago. I thought the head gasket was bad because after replacing the thermostat, it just kept overheating. The thermostat looked like it had never been changed( really rusty and nasty. The coolant that was in the car was rusty in color also. I have since replaced the thermostat(with an oem 195). I have also drained the radiator and refilled with a 50/50 mix of coolant and water.
Still I have this overheat problem.
I had the block tested, it checked out find.
I have been told everything.
Change the radiator
Change the water pump
Get a bigger radiator. ( ijust got a 4 core from another camaro i just bought)
Also, this car has 2 fans......only one turns on and off when the car gets hot.
even with the AC on only the drivers side fan works.
I do know that the other fan works, i disconnected the relay so I could jump the fan to get it to turn on. I am also getting alot of bubbling. I guess that is just from the boiling coolant. I have since replaced the fan relay, still nothing from the passenger side fan. I have bought a new water pump, but I am waiting to get some advise before I go through all this crap.
I love driving the car, but I cant figure this overheating problem out.
If anyone could help me out, that would kick ***. I cant drive it at all now and it is pissing me off...thanks guys
Please contact me at: alpineaudioguy@hotmail.com
thanks again

 

There are 2 things that I can can think of to check for that you didnt mention.
make sure you have an air dam(looks like a big piece of plastic hanging down under the radiator, and it scrapes on the road all the time), and check to see if the fan switch has been broken. its on the pass. side of the engine between the last 2 cylinders. if its broke you can get the fan to run all the time by grounding the green wire going into the relay.

this pic shows which wire on the relay to ground.