2011 Aveo overheating, blowing out coolant

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"?

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Originally Posted by 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"?

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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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Is this a tool only the dealership would have?

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Originally Posted by MuteMarmoset

Is this a tool only the dealership would have?

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


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Would you do a combustion test before a compression test?

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Originally Posted by MuteMarmoset

Would you do a combustion test before a compression test?

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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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Try a new coolant reservoir cap.

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.

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Originally Posted by MuteMarmoset

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

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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.

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Originally Posted by avguy

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.

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


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Quote:

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Originally Posted by avguy

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.

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Nobody has quoted me any temps. But my regular mechanic said to me yesterday that even when it boiled back over, that he did not feel that the engine was heating.

Today I had to go out, and I made arrangements in case I ended up on the side of the road somewhere. I drove about 20 miles, and only about 4 miles out did the gauge think about going more than halfway. But when I parked, I thought I heard gurgling/boiling. I drove the 20 miles home and the same thing happened, with the sound and the needle.

I didn't feel a great deal of heat from the engine, but when I opened the hood, the reservoir was boiling and steam was coming out around the cap. So I closed the hood:)

I don't want to try driving it to town but am going to find someone else that can pick me up a new cap and we'll try that.

Quote:

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Originally Posted by MuteMarmoset

Nobody has quoted me any temps. But my regular mechanic said to me yesterday that even when it boiled back over, that he did not feel that the engine was heating.

Today I had to go out, and I made arrangements in case I ended up on the side of the road somewhere. I drove about 20 miles, and only about 4 miles out did the gauge think about going more than halfway. But when I parked, I thought I heard gurgling/boiling. I drove the 20 miles home and the same thing happened, with the sound and the needle.

I didn't feel a great deal of heat from the engine, but when I opened the hood, the reservoir was boiling and steam was coming out around the cap. So I closed the hood:)

I don't want to try driving it to town but am going to find someone else that can pick me up a new cap and we'll try that.

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It definitely sounds like the cap has failed; but just for peace of mind, I would also go ahead and pressure test the cooling system in the car. (Harbor Freight sells a cooling system pressure tester for $125) if it holds pressure without dropping, the system is airtight. But if the pressure drops, start checking underneath and in the engine compartment for any coolant leaks. (I did that, and turned out my water pump was kaput.)


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Originally Posted by 2010AveoLT

It definitely sounds like the cap has failed; but just for peace of mind, I would also go ahead and pressure test the cooling system in the car. (Harbor Freight sells a cooling system pressure tester for $125) if it holds pressure without dropping, the system is airtight. But if the pressure drops, start checking underneath and in the engine compartment for any coolant leaks. (I did that, and turned out my water pump was kaput.)


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I will talk to the garage that's going to do the testing. First a new cap, then we'll see if I can get it there without cooking the engine.

I got the cap yesterday and put it on, but didn't have a chance to take the car out. Tonight I drove to the convenience store, which is 7-8 miles. It was fine on the way there. I checked under the hood, there was no boiling.
When I came back, I wasn't a mile away from the store when the needle went up to 3/4, and I took my foot off the gas (it wasn't on very much), and the needle dropped back. I had a hill to go up and used the gas with no movement from the needle. When I got home, I checked under the hood again, and there was no boiling in the reservoir, but it was a short trip.

It smelled hot when I got out, but it's had coolant sprayed all over and I imagine that will take some time to wear off. So smell is no help to me. I may try and take a slightly longer drive tomorrow, but I don't know where to go from here. I'll pass this on to the mechanic who is going to work on it this week, but not till Wednesday, and I'm worried about whether it can be driven the 30 miles.

Have you or your mechanic been refilling coolant and bleeding air out of the system since this issue started? If not, it's likely that quite a bit of the coolant has been replaced by air that needs to be purged out.

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Originally Posted by avguy

Have you or your mechanic been refilling coolant and bleeding air out of the system since this issue started? If not, it's likely that quite a bit of the coolant has been replaced by air that needs to be purged out.

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The mechanics may have, I haven't. And I have put water in it twice this week. Is this something I can do myself today? before I take it out again? It only has water in it until we can stop the boiling/heating.

One problem with using water is that the ratio gets skewed, and your vehicle no longer has the proper cold weather protection. So at this point you should buy a bottle of concentrated coolant and do the next topping off with just that alone (any of the 'lifetime all-vehicle' coolants is fine). That hopefully might restore the coolant/water ratio back to where it should be, but you MUST absolutely test the coolant with the proper tool before Winter sets in. The other problem with tap water is that it may contain minerals which are harmful to the metal cooling components. For that reason it's important to buy and use distilled water, instead of taking it from a tap.

AFA purging the air, I don't know if the second gen Aveo is different than my vehicles, but in any case this procedure should work fine. With the vehicle cold, remove the coolant overflow cap and then idle the vehicle for an extended period of time, with the heater and blower on the highest setting. Bump up the revs to 2-3K for short periods of time, in order to get it heated up faster. While it's idling, watch the overflow tank and top off with the concentrate as necessary, filling somewhere between max and min. Then once the level is no longer dropping, put the cap back on and give it 5 more minutes of idling to let the system fully pressurize. Then shut it off and wait for it to completely cool down in order to check the overflow level again. Top off as necessary, and then get it heated up again, this time with the cap left in place. Repeat that sequence until the level no longer drops.

Quote:

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Originally Posted by avguy

One problem with using water is that the ratio gets skewed, and your vehicle no longer has the proper cold weather protection. So at this point you should buy a bottle of concentrated coolant and do the next topping off with just that alone (any of the 'lifetime all-vehicle' coolants is fine). That hopefully might restore the coolant/water ratio back to where it should be, but you MUST absolutely test the coolant with the proper tool before Winter sets in. The other problem with tap water is that it may contain minerals which are harmful to the metal cooling components. For that reason it's important to buy and use distilled water, instead of taking it from a tap.

AFA purging the air, I don't know if the second gen Aveo is different than my vehicles, but in any case this procedure should work fine. With the vehicle cold, remove the coolant overflow cap and then idle the vehicle for an extended period of time, with the heater and blower on the highest setting. Bump up the revs to 2-3K for short periods of time, in order to get it heated up faster. While it's idling, watch the overflow tank and top off with the concentrate as necessary, filling somewhere between max and min. Then once the level is no longer dropping, put the cap back on and give it 5 more minutes of idling to let the system fully pressurize. Then shut it off and wait for it to completely cool down in order to check the overflow level again. Top off as necessary, and then get it heated up again, this time with the cap left in place. Repeat that sequence until the level no longer drops.

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I am on well water that would have gone through a filter/softener. But I will remember that should I need it again.

And about the burping: I watched some videos, and they were all big on wedging a funnel into the overflow tank opening. I take it that's not necessary if you just use the funnel when topping up and pour carefully? The videos also recommended squeezing the radiator hoses as it idles, to both get out air and to see if the two hoses were at the same temperature. They also filled the reservoir to the top, which I thought you weren't supposed to do.

How long is "an extended period of idling"?

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Originally Posted by MuteMarmoset

I am on well water that would have gone through a filter/softener. But I will remember that should I need it again.

And about the burping: I watched some videos, and they were all big on wedging a funnel into the overflow tank opening. I take it that's not necessary if you just use the funnel when topping up and pour carefully? The videos also recommended squeezing the radiator hoses as it idles, to both get out air and to see if the two hoses were at the same temperature. They also filled the reservoir to the top, which I thought you weren't supposed to do.

How long is "an extended period of idling"?

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I've never done the funnel wedge thing, but I also wouldn't knock something like this that I've never tried myself. Squeezing the hoses is fine, but I never saw bubbles from the tank when doing that, and gave up on it quite a while back. No reason to fill the tank all the way - just monitor and continue topping off to no more than the max line.

AFA how long to idle, it's basically just until the t-stat opens, allowing coolant to circulate throughout the entire system for a few minutes. So if you don't have an OBD realtime reader to tell you what the coolant temp is, then checking to see if both rad hoses are hot is a good alternative way to know that coolant is moving through the system.

I idled it for 45 min. during which I added coolant twice. It did not take a great deal so if it's now driveable, then I will need to get it tested/or emptied and filled with all anti freeze for winter.

The engine ran smoothly the entire time, and the gauge did not tick above half, even when revved. After I replaced the cap, I ran it for a further ten minutes and it was fine. The hoses heated up as they should and there was no boiling. There was no bubbling up when I squeezed the hoses.

I am going to try and drive it to town tomorrow (25 mi). I will put a jug of water in the car in case. I did have it out for a short drive with a hill this morning, 15 miles round trip, and had no issues. But there has been a check engine light on since the first boil over two weeks ago, and I need someone to run a diagnostic tool on that.

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Originally Posted by MuteMarmoset

… I will need to get it tested/or emptied and filled with all anti freeze for winter. ….

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That's something you could DIY for less than a shop would charge, and it wouldn't be all that much work either. Just buy a tester like one below, along with an inexpensive fluid pump, and find out what the current coolant protection is. Then, assuming it needs to be improved, pump out the overflow tank contents. Then refill the tank with concentrated coolant, run for a day or so to fully remix the system, then test the coolant again. Just continue doing that until the protection is back to where it needs to be - probably not more than 2-3 reps would be needed to get it back to 50-50.


https://www.amazon.com/Performance-T...9611380&sr=8-4

I will certainly do that once the dust settles.

I drove the car to town today. After burping the system and putting in coolant, it seemed to be running really well. No trouble getting there, then I stopped to drop something off. When I started again it overheated in less than 3/4 of a mile. I called the mechanic I was heading for anyway, and he told me to let it cool for a half hour. I opened the hood and it was so hot I could barely touch the support rod.

After a half hour, it started up again fine, and I drove to the garage, which was perhaps 4 miles away. It would be my luck that his diagnostic tool was acting up, but the code for the check engine light did indicate a cooling problem. He opened the hood to listen to it and we stood there talking about what had been done so far. That's when we could both hear a change in the running sound. He stuck his hand inside the front and found the cooling fan was not working.

I'm not technical enough to explain the entire process but he used a little plug in device that would relay around the fan to see if it was actually functional, and it was. Then he got under the car and what he found, was that the contacts for the fan were corroded and covered in gunk. He said the reason that the acting up was so spotty, was that out on the highway it's a smooth run and continuous working, but when you stop and start like running errands in town, it was more likely to stick and stop working. Then he asked if the AC was working well.

Back in June after the first time it boiled over, I discovered my AC wasn't working and it turned out I needed freon. Both my own mechanic and the one where I took it for that work told me that the AC had nothing to do with the overheating, which was wrong. If the fan is not working right, you're not going to get the cool air in, nor cool air over the engine. And there were times that it seemed not to be putting out enough cold air and I put it down to our unusually hot summer.

Bottom line (for now): He cleaned the contacts off and everything looked good. I was able to drive around town on errands, and then the 25 miles home with no issues. He said it should be fine, but it it happens again, I would likely need a new cooling fan.

About 10 years ago I bought a 2001 Audi A4 Avant 2.8-6 from a small used car dealer for almost nothing, due to the fact that it would puke coolant out and they didn't want to fix it. Turns out the timing belt was incredibly loose and essentially wasn't engaging the water pump at low engine speeds. That particular car also had an aux factory installed electric water pump, for emergencies/parked too hot incidents. Naturally, it didn't work either, and the heat from the iron block (being trapped with no actual coolant flow) would "boil over" the overflow tank in traffic, or when parked hot.

A 2011 shouldn't have a timing belt driven pump, but that doesn't mean the pump is still working like it should, or some blockage is preventing it from pushing the correct amount of coolant thru the system.

Hopefully it is just the fan, after all. The ac condenser sits in front of the radiator, so all of the exchanged heat goes right into/past the radiator, and without the fan the coolant will get too hot and expand past the capacity of the system.

Thanks for the input.

I have been testing the fix. I drove around town then home with no problem. Then I let it sit three days before taking it out for a couple of short drives, and it was still good. I have since been to town and back twice, and it's still not overheating, so I'll likely bite the bullet and head to the city this weekend which is about 110 miles round trip.

I don't know as I'll ever fully be confident in the car again, as the first time this happened was June, then it didn't do it again for over two months. But at least now I have a pretty good idea of how to deal with it.