Need some help before I commit into a weekend job. Now I have a freind with a 95 camaro Z28 and the car has been running hot. We went ahead and replaced the whole cooling system figuring the car could use it anyway. So everything was changed (water pump, 180 thermostat, fans and got a radiator from a local shop used but acid cleaned and flushed) but the car would still run hot. After making sure everything was working correcly we've come to conclusion the the head gasket may have took a ****e. Problem with that is that we've seen no water in the oil nor oil in the water. The car does not spit fluid or steam out the tail pipes and no steam comes from the cap when we first start the car. The car runs just fine but will overheat in a matter of 10 minutes so we pulled out thermostat to see if we had fluid moving after the car had cooled down and once we started and let the car idle for about 30 minutes we noticed that the temp hardly moved at all and we took the car for a ride and ran it hard to see wht would happen and the car still ran cool. We replaced the thermostat 3 times and the car kept getting hot but ran fine without one. Any help guy's would be greatly appreciated and sorry this thread was so long.

Not putting it (thermo) in upside down are you? sorry, had to ask. That is a reverse cooling motor, correct? with thermo in, leave rad cap off with engine running and look for bubbles in the radiator. if you get bubbles you have a gasket problem. IIRC, there is a sweet spot with those motors that if the head is cracked in a certain spot you wont get oil/water mixed, just runs hot...look for bubbles...good luck!

Sniffing the overflow tank with an exhaust gas probe is another check for blown head gasket, but I would think it would also be bubbling at that point.

Did you open the two bleeders on the front of the motor to let air out of the cooling system each time?

It sounds like air in the system to me. You could also try the old trick of drilling a hole in the thermostat to let the air past before the stat opens. Seems like it should all blow out once the thermostat opens, but I guess not if GM found the need to put bleeders on the system.

Some later model cars just get air trapped in there and it's tough to get out (later S Blazers come to mind).

dont condemn the head gasket yet!!!eric has a good point on the drilling an 1/8 hole in the outer rim of the tstat...(between the pod and the gasket area)also make sure the air dam is in place...air under the tstat will prevent it from ever opening...and no air dam will make it overheat down the road, but will keep cool at idle...

dont condemn the head gasket yet!!!eric has a good point on the drilling an 1/8 hole in the outer rim of the tstat...(between the pod and the gasket area)also make sure the air dam is in place...air under the tstat will prevent it from ever opening...and no air dam will make it overheat down the road, but will keep cool at idle...

The only thing is that the car had been running great and then while at a light the car started to over heat. Even after getting the car back to the house we still could not get the car to run cool at all even after replaceing the tstat and bleeding the system. And yeah it is a reverse cooling. Did't get time to pull the gaskets out and the car is the only trans he's got right now. Gotta find out for sure and soon.

sounds dumb, but some serp belt setups will allow an alternate (and incorrect) route for the belt...make sure the belt is spinning the pump in the correct direction...also make sure you got a pump that ia moving water in the correct direction...shoot the rad with a raytec (infra red thermometer) to see if there are cold spots in the radiator...the thing that gets me wondering is that the car will run cool without the stat, but will overheat with...thats why i`m thinking the pump is spining backwards...could try running the stat upside down to check the theory, but i dont know if it`ll fit in the waterneck that way...just a thought...

Have you ran a compression test on the engine? I had a turbo Eclipse that blew a heaad gasket and I never had any symptoms aside from the it running hot. It had just as much power as it always did. No oil/coolant mix, heater still worked well, just ran hot. I couldn't explain it. Run a comp. test on it and see what you come up with. Good luck.

sounds dumb, but some serp belt setups will allow an alternate (and incorrect) route for the belt...make sure the belt is spinning the pump in the correct direction...also make sure you got a pump that ia moving water in the correct direction...shoot the rad with a raytec (infra red thermometer) to see if there are cold spots in the radiator...the thing that gets me wondering is that the car will run cool without the stat, but will overheat with...thats why i`m thinking the pump is spining backwards...could try running the stat upside down to check the theory, but i dont know if it`ll fit in the waterneck that way...just a thought...

The water pump on an LT1 runs off of the cam not a serpentine belt like most other do so the possibilty of putting it on wrong would be very hard to do also I don't think the tstat will no fit into the waterneck upside down. I've actually never tried to put it in that way. Thanks for your help.