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1991 Corvette ZR-1 · 06-20-2022

Have you had a chance to check the air gap between the radiator underneath the shroud? How quickly does it overheat? In changing the thermostat, how did you refill the coolant? When refilling the coolant and it appears full in the surge tank it is possible to still have a decent amount of air still in the system. A trick that one of our forum veterans taught me was when the engine is cold and you start it, put your hand on the coolant tube outlets on the injector housings and the cam covers. If the cam covers are getting hot, but the coolant tubes are staying cold, air pocket issues. If the tubes get hot and the cam covers stay comfortable to the touch during that time, you are good to go.

Also, surge tank should have a visible return stream while the engine is running. While the engine is cold, take the surge tank cap off and start the car and observe if that is present. You can also check your fan operation by using a paper clip to jumper the diagnostic terminal when the Key in the on position but not cranking it. That is a start anyway, hope some of that is helpful info.

06-20-2022	#2
1991 Corvette ZR-1 Join Date: Sep 2018 Location: Florida Posts: 306	Re: Overheating issues. Have you had a chance to check the air gap between the radiator underneath the shroud? How quickly does it overheat? In changing the thermostat, how did you refill the coolant? When refilling the coolant and it appears full in the surge tank it is possible to still have a decent amount of air still in the system. A trick that one of our forum veterans taught me was when the engine is cold and you start it, put your hand on the coolant tube outlets on the injector housings and the cam covers. If the cam covers are getting hot, but the coolant tubes are staying cold, air pocket issues. If the tubes get hot and the cam covers stay comfortable to the touch during that time, you are good to go. Also, surge tank should have a visible return stream while the engine is running. While the engine is cold, take the surge tank cap off and start the car and observe if that is present. You can also check your fan operation by using a paper clip to jumper the diagnostic terminal when the Key in the on position but not cranking it. That is a start anyway, hope some of that is helpful info.