2011 Aveo overheating, blowing out coolant

[MuteMarmoset]

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.

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.

[2010AveoLT]

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.

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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[MuteMarmoset]

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.

[MuteMarmoset]

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.

[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.

[MuteMarmoset]

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.

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.

[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.

[MuteMarmoset]

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.

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"?

[avguy]

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"?

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.

[MuteMarmoset]

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.