I have a 97, Lt1 formula. I have owned this car for 7 years.

I have replaced the radiator and cap because it was leaking and replace the thermostat about a year ago. Both my fans work at low speed and high speed with and without a/c on. Alternator is charging good, and has lots of power.

In the winter i dont have any problems at all with it but as soon as the temp outside hits 90's, it starts getting hot enough to boil over in the overflow if driven in stop and go trafic for more than an hour. In the summer time i pull the thermostat out to help with the problem but this summer it seems not to be helping. On the highway it does not heat up as fast, but will get to hot for comfort.

I have not replaced the waterpump, but I have not convenced myself yet that is the problem. When checking the temps at the radiator in/out, both are very close to the same (230-240). To me if the water pump was bad the temp would be LOTs colder on the out side due to low flow.

I am a good mechanic I think, we all have that one and this is mine. I have PSI and Block checked, it came back good, no water in the oil and no water in the exhaust. I do not loose coolant unless i let my wife drive it to work, and when she gets home it will be boiling out the overflow. I also have bleed the air out of the system.

 

LT1 temperature (without a EWP) fluxuate alot, and the highspeed fans will not come on til 235* so you have not described an overheating condition.

Check the airscoop passageway in the nose and make sure the passage is clear and nothing is in there or plastic shields have blocked the air flow.

Put the thermostat back in! The thermostat among other things allows the coolant in the radiator to have a good amount of cool down time, and regulates cooling. Also without the t-stat the engine can over cool and dump more fuel into the engine.

 

You also may want to check your coupler that goes from the block to the WP. Had a friend find his to be stripped.

 

Also check for coolant flow coming from the steam pipe. When it's cool, take the cap off and look down the neck where the return from the line feeds in while it's running and confirm it's not blocked.

 

Before spending any more time trying to help, let's wait until he comes back to the site and acknowledges the responses he already has. He posted on 7/14, signed off two minutes later, and never came back to the site and signed in again.