2011 Aveo overheating, blowing out coolant

[MuteMarmoset]

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"?

[2010AveoLT]

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"?

They do have a special tool where they can see if combustion gases are escaping into the cooling system that uses a special dye that changes color in the presence of those combustion gases.


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[MuteMarmoset]

Is this a tool only the dealership would have?

[2010AveoLT]

Is this a tool only the dealership would have?

Nope, harbor freight sells them for $25 https://www.harborfreight.com/combus...tor-64814.html


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[MuteMarmoset]

Would you do a combustion test before a compression test?

[2010AveoLT]

Would you do a combustion test before a compression test?

Yes, because your Aveo still starts reliably; when compression gets low, it will be hard to start or won’t start at all.


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[avguy]

Try a new coolant reservoir cap.

[MuteMarmoset]

If this were the issue, would it not overheat every time the car was driven?

My garage guy decided not to try the compression test after all. I'm going to take it to another fella that can do the combustion test first, then we'll proceed from there. The trouble is that so many different garages and techs at the dealer's are giving conflicting stories about what it could be. The latest suggestion is an air lock.

[avguy]

If this were the issue, would it not overheat every time the car was driven? … .

You're saying it's overheating, but I don't see any mention of actual coolant temps here (either measured or from OBD), and I suspect the shops are not finding a problem because the engine is actually not overheating. In prior forum threads on this issue, IIRC there was no mention of overheating, just a reservoir cap that was no longer holding pressure.

[2010AveoLT]

You're saying it's overheating, but I don't see any mention of actual coolant temps here (either measured or from OBD), and I suspect the shops are not finding a problem because the engine is actually not overheating. In prior forum threads on this issue, IIRC there was no mention of overheating, just a reservoir cap that was no longer holding pressure.

Or in cases like mine, a coolant leak was found upon closer inspection.


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