Chevrolet Repair Questions? Ask a 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.