To begin, I have been experinencing this issue for about three months now. It began when a local mechanic did a cooland flush which caused the engine to over-heat and the heater issue began. Prior to that the vehicle had no issues. From that point the mechanic told me that the there was air in the coolant system which needed to be bleeded. He bleeded the air and the heat returned, however, a few days later the head would go again. This was repeated 4 times.

I then took my car to a second mechanic who changed the thermostat and tested the water pump, which was fine. Air continued to enter the cooling system. as a reuslt, the mechanic concluded that the head gasket was leaking/blown and had to be changed. He changed the head gasket for me and the car went back to normal for a month and a half. This morning the heat went out again

My g35 has 103k miles and is well mainatined. I was wondering if any one has nay thoughts.