It kept on over heating so when I got home I added a whole gallon of dex cool. I cannot find a external leak.maybe any leak it had air pocket but I don't seea leak but maybe internal?

 

Please post the info on your vehicle; and when was the last time cooling system was serviced?
Welcome to Chevy!

 

The vehicle in question is a 2004 Chevy Trailblazer with a 5.3-liter 4spd auto, and it is the ext lt model. it was serviced by the previous owner three months ago. New radiator, new fan, new ECM, new thermostat, new water pump, and the top end was rebuilt, with the heads shaved. Just two days ago, i had the AC fixed. As I was driving back from getting the AC fixed, it kept overheating, so i bought a gallon of Dex-Cool, and after the engine cooled off, i added the whole gallon of antifreeze. i think it just had an air pocket in it. That remains to be seen..

 

How long/how many days a week have you been driving it?

 

just from mocow idaho to pullman wash about 9 miles ans as soon as the computer said check gauges i saw it was over heated. i backed off the gas and it cooled off and i drove it easy to my place and parked it.