I have a 2011 Aveo with 80,000 km on it. With the current state of things, I have not been driving a lot, maybe going to town once a week, about a 50mile round trip.
Back in June the car suddenly overheated and had blown coolant all over. I had it towed to my mechanic and they could find nothing wrong with it. He replaced the thermostat. The next week my AC failed, and I had to take the car into town to a garage that could refill the freon. They also tested it (I don't know what tests but will ask them) for what caused the overheating and found nothing wrong.
Since then, the car has been doing the same round trip once a week, and on one occasion, I did a 120 mi round trip, all with no problems. A week ago I drove five miles down the road to a convenience store, and it overheated coming back, blowing out the coolant again.
I called the guy who works on my car and he said to fill it with water and drive it down, which is about 17 mi. I had no problems at all. So far he has replace the thermostat again, and the cracked housing that the thermostat is bolted to. But when they ran the car, it overheated again and blew the water out. They plan to do a compression test in the morning, but can't say that will tell them whether it's the head gasket or not. Apparently it will only tell whether the leakage is on the inside or the outside.
What has confused the mechanic is that a blown gasket usually shows itself in other ways, and this car runs as smooth as you could ask. Plus, it has not done this since June.
The housing by the thermostat was $500 and didn't solve the problem. Is there any direct method of saying "yes it's the head gasket"?