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Discussion Starter · #1 ·
The short version of this is that our Ascent Touring with 14k miles overheated on a flat 35 mph street in stop and go traffic for no apparent reason. After towing it to Subaru of Portland, they were unable to reproduce the problem or find anything wrong besides some debris (leaves) on the radiator. It hasn't happened since, but we live in fear of it happening again randomly in the future since the cause was never determined to my satisfaction.

Long version: This happened back in late July. My family was on vacation at the Oregon coast. We drove over the mountains to Portland with no problems in the morning. We stopped for some shopping at Target. The temperature was between 80 and 85. The car had been resting in the shade for about 40 minutes on a small incline. My family got done shopping, and we started off. About 5 minutes after starting off again on a flat road in 35 mph stop and go traffic, I got the alert: "Elevated Coolant Temperature". I looked down, and the temperature gauge was pegged, past the red. I pulled over, opened the hood, and the coolant was bubbling in the reservoir. I have a video, but the forum won't let me post it.

Subaru of Portland was very thorough because I was about to drive 6 hours back through desert to get home with little kids in the car. I even talked to the head service mechanic, but they found nothing wrong. No engine code was logged either which I find incredibly bizarre. I'm not buying leaves in the radiator as a cause obviously because we didn't pick up any debris while parked at Target, and the car was experiencing way more load before Target. We were not towing anything either.

So there you have it. Anyone heard of overheating issues or have any clue what would cause such a strange fluke? My theories are a thermostat sensor that got stuck and then unstuck itself. Or some weird software gremlin. I unfortunately was not thinking fast enough to open the hood before I shut the car down to check if the radiator fans were running.
 

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Never heard of it. Please keep us posted. I too would have been concerned especially given the driving terrain that you would be traversing.

I am not a mechanic so this link may not offer anything relevant to your situation, but since you are exploring: https://suburbservice.net/certain-subaru-models-suffer-engine-problems-fix

Any tailpipe smoke?
Recovery chamber coolant color?
Was the pressure cap recently adjusted?
Slipping accessory belt?
Collapsing bottom radiator hose?
Low oil level?
Faulty thermostat? It might be the beginning of a sticky thermostat.
 

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What temperature gauge is that? I don't think my Ascent has a needle gauge with a red zone on the instrument cluster.
F.S.
If you have a trim level with the full color LCD under the top hood, you have one display that's three gauges. You can select various information to display in each gauge position. Oil temperature is one option.

Any of these can be replaced with one of those gauges.

1609
 

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How do you change/sort the "guages"?
Go into the MFD Settings, its the last screen at the bottom of all the MFD screens, press and hold Enter. Then go down to the 2nd menu item Display/Beep and select that. Then go to the 2nd menu item Favorites and select that.

You should see the 3 available Favorites positions with the Green arrow highlighting the leftmost position. Press Enter to select that position or arrow to another position. When you select a position you will get a list of available screens. Arrow down to the one you want and press Enter to choose that screen, you will then be taken to the next position where you have to press Enter to select that position, and go through the choices again.

When you have picked all 3, arrow over to Set and press Enter. Then Go Back to get out of the Settings Screens.

Your new Favorites screen is the 3rd from the top on your MFD.

Since Coolant Temp is already a guage, lower left of the Tach, it isn't a Favorite option, regardless of what Robert says ?
 

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Since Coolant Temp is already a guage, lower left of the Tach, it isn't a Favorite option, regardless of what Robert says ?
LMAO!!!

Mine is actually set to oil temp. ?

On a serious note, I wish they would add boost and CVT temp.
 

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I do have oil temp set up in the upper display. I was just wondering what the OP was looking at when he saw the alert message and then "looked down" at a gauge that was "pegged, past the red."

Gary, I need to look at my lower left gauges, never noticed something over there! I am traveling and (sniff) am driving an awful rental Edge instead of my Touring.

F.S.
 

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Discussion Starter · #10 ·
What temperature gauge is that? I don't think my Ascent has a needle gauge with a red zone on the instrument cluster.
F.S.
As others have noted, there's a coolant gauge in the lower left of the driver dash. Physical gauge, not digital. I was panicking, and wanted to turn the engine off as soon as possible to prevent damage, so I didn't bother with flipping thru to get the oil temp digital gauge. In hindsight there's a few other things I could have checked, but I never dreamed that there'd be no engine code and it wouldn't be reproducible.

To answer these queries:
Any tailpipe smoke?.
Recovery chamber coolant color?
Was the pressure cap recently adjusted?
Slipping accessory belt?
Collapsing bottom radiator hose?
Low oil level?
Faulty thermostat? It might be the beginning of a sticky thermostat.
I did not note any smoke or anything else wrong aside from the bubbling coolant. Everything checked out except for they found the coolant slightly low, possibly from it boiling off. It's never had any service aside from two oil changes prior to this incident.

I keep the oil temp up on the display now and keep an eye on the coolant temp, but realistically it happened so fast before, that I doubt I'll catch it early next time. I'll make sure to update this post if/when it does happen again.
 

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Thanks for the update.
 

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If you saw bubbles in the reservoir , I'd suspect it was overheating, up in the 250F ballpark with coolant and pressure cap. Why is the question. Could have been a stuck coolant thermostat, or a chunk of crud in the water pump impeller. A few leaves is unlikely.
I had a car that ran hours at 85mph, but bump it up to 87, and it'd start climbing the gauge. A couple years later, the water pump started leaking, and when I changed it, I found the impeller had a couple uncast fins in it. Never overheated after the new pump was in. The old impeller would start to cavitate and water circulation would stop above a certain RPM..
 

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I had my ascent at 15k miles now and i notice that the coolant on resevoir is below the low level..is this a sign of leaking system?
 

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Discussion Starter · #15 ·
This was likely a fluke, since I haven't heard of anyone else having problems. That said, I thought I'd give an update. Our car overheated again. We're at 22k miles now. We were driving back from vacation (again). We pulled over to switch drivers, and a couple minutes later we got the coolant temp alert.

I called our Subaru dealership and the only thing they could think to try was compare the top radiator tube temp to the bottom one. The top was warm, the bottom was cold. He thought that indicated a faulty thermostat sensor. I hung up with him and was about to call for a tow, when I decided to try starting the car one more time. Bam, it magically fixed itself, and we were able to drive home with no problems.

Subaru HQ was still completely unhelpful, but my dealership stepped up, and replaced the thermostat anyways. Hopefully that fixed it, but there's no way to tell for sure.
 

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I also had the low coolant level. Dealer checked and did not find any cause.
I had my ascent at 15k miles now and i notice that the coolant on resevoir is below the low level..is this a sign of leaking system?
I also had the low coolant level. Dealer checked and did not find any cause. I'm keeping a close watch on the resevoit level these days.
 

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This was likely a fluke, since I haven't heard of anyone else having problems. That said, I thought I'd give an update. Our car overheated again. We're at 22k miles now. We were driving back from vacation (again). We pulled over to switch drivers, and a couple minutes later we got the coolant temp alert.

I called our Subaru dealership and the only thing they could think to try was compare the top radiator tube temp to the bottom one. The top was warm, the bottom was cold. He thought that indicated a faulty thermostat sensor. I hung up with him and was about to call for a tow, when I decided to try starting the car one more time. Bam, it magically fixed itself, and we were able to drive home with no problems.

Subaru HQ was still completely unhelpful, but my dealership stepped up, and replaced the thermostat anyways. Hopefully that fixed it, but there's no way to tell for sure.
That sucks that it happened again. Glad that your dealer was able to think quick and also stepped up to attempt a fix. It's odd that its triggered by a brief break after a long drive. Might try to replicate that scenario a few times after arriving home from a long trip to see what happens.

Also, take a look at the oil. IMO it's cheap insurance to change it after an overheating event. Just my 2 cents, though I'm not sure how sever it needs to be to start breaking down the oil.
 

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Discussion Starter · #19 ·
...And it's happened now for the third time. A few months ago, after Subaru corporate was unhelpful, my dealer replaced the thermostat. But apparently that wasn't the solution because it overheated again. We were stranded on the highway in 90 degree heat with no water on our way to pick up the kids from day care. Fortunately, we were only 15 minutes from our dealership, so the service manager drove out with a loaner. I still don't know if he was able to drive it back or had to tow it.

So this is the third time a dealer will be looking at the problem. The last two times it was not reproducible and nothing was found, so I'm not holding out much hope. Am I crazy to start thinking about lemon law here? 24k on the odometer, and it has broken down 3 times in less than a year. We're lucky it's only been inconveniences so far, but I also wonder about damage to the engine since the car doesn't alert me until the coolant is literally boiling.

If I could trade it in without being robbed, I would.
 

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How about any codes or info from the computer... Has the dealer been able to pull any of that info? And were you able to at least get a picture or video of the temperature gauge when it happened to show them?
It’s so frustrating when you’re having a problem and they can’t reproduce it. See my tpms saga.
 
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