Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Hello and thank you for your question,Can you tell me what your working on, year make and model as well as your engine size?
Okay its a 2003 , I need the model , and engine size as well.
Okay, if you have had to add a gallon of coolant into the overfill tank then that indicates you have a coolant leak and now likely have trapped air in the cooling system. I would start first with having a cooling system pressure test performed to determine where the coolant is leaking and after the leak is found and corrected then do a refill and bleed the system. See the drain and fill steps in the link below. Copy and paste the link to your browser to open and view them.https://dl.dropboxusercontent.com/u/104923897/Drain%20and%20fill%20Feb%2017.pdf
That is a sure sign of having trapped air in the cooling system. You need to check for leaks with doing the pressure test and then fill and bleed the system. I think this will resolve the problem.