Overheating warning yet the engine wasn't that hot. What went wrong?

[yescats]

I just got off the highway after driving 50 miles or so. All of a sudden I get a message that the car is overheating. A few seconds later a message the A/C was shutting down. So I pulled over at a gas station and shut off the engine. The engine didn't seem hotter than normal. Within a couple of minutes the radiator fans shut off so I carefully opened the radiator cap. There was no hiss or steam, everything seemed normal. I bought some anti-freeze. I was able to add a half a gallon. Started it up and the meter showed the temperature was completely normal. Drove back home no problems.

I feel the car wasn't really overheating. It didn't feel hot and was down to normal temperature within five minutes. Was it a computer glitch? This doesn't make sense.

[Caswell239]

There's a few other people with this issue recently but nothing was discovered yet.


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[Brett64D]

I have been having this same issue for a while. I have changed the temp sensor, thermostat and flushed the system. It still happens. I am going in for an emissions test tomorrow to see if I have a leaking head gasket. The car is not visibly leaking water but every time this happens my water level is low even though the reserve tank is at the full mark.

[Rock-It Man]

If you were able to add half a gallon, something is wrong.

Read the fill procedure in the manual. The point is to get all the air out of the system.

You need to start with a cold engine. Run it with the radiator cap off until the coolant starts circulating, and then keep adding coolant to the radiator until its full. Then cap the radiator and fill the surge tank to the right level.

[ron123]

Originally Posted by Rock-It Man

If you were able to add half a gallon, something is wrong.

Read the fill procedure in the manual. The point is to get all the air out of the system.

You need to start with a cold engine. Run it with the radiator cap off until the coolant starts circulating, and then keep adding coolant to the radiator until its full. Then cap the radiator and fill the surge tank to the right level.

Additional questions ...
Was the radiator 1/2 gallon low or was it the plastic surge/expansion tank that was low? If added directly to radiator, agree with previous post, there is a leak somewhere.
Did you look at the Driver Info Center display to see what digital temperature reading it was showing in degrees? (not the generic H/C temp analog gauge)
If I suspect low coolant or coolant circulation problem while driving, I quickly turn on the heater to see if it is blasting hot air ... if no very hot heat that means water is probably below the level of the water pump and not circulating in the engine.
If water is below the level of the coolant temperature sensor then the reading would not be accurate at all.
Ron

[cajun1le]

Has the original poster tried pressure testing the system to see if there is indeed a leak within the coolant system? Another thing to consider is that there may not necessarily be a leak anywhere. This is by no way a knock to the owner with the problem, but I think everyone is assuming that the owner has been properly servicing the coolant system. The car in question is a 2011 model year. It is possible that the water content of the glycol mix evaporated overtime during normal use. Also, the coolant recovery tank is not a sealed vessel, but rather just a cavity for steam/hot coolant to condense and be used again. The recovery tank does a good job at recovering coolant but to see 1-3 quarts of evaporation loss over 5 years is to be considered normal if the systems has never been serviced or changed.

On a side note, I'm rather curious what the specific gravity of the coolant was before the owner added that half gallon of coolant to the system.

Best of luck to you, I hope this helps point you in the right direction.

Napa cooling system pressure tester part number: BK 7003025

[yescats]

Originally Posted by cajun1le

Has the original poster tried pressure testing the system to see if there is indeed a leak within the coolant system? Another thing to consider is that there may not necessarily be a leak anywhere. This is by no way a knock to the owner with the problem, but I think everyone is assuming that the owner has been properly servicing the coolant system. The car in question is a 2011 model year. It is possible that the water content of the glycol mix evaporated overtime during normal use. Also, the coolant recovery tank is not a sealed vessel, but rather just a cavity for steam/hot coolant to condense and be used again. The recovery tank does a good job at recovering coolant but to see 1-3 quarts of evaporation loss over 5 years is to be considered normal if the systems has never been serviced or changed.

On a side note, I'm rather curious what the specific gravity of the coolant was before the owner added that half gallon of coolant to the system.

Best of luck to you, I hope this helps point you in the right direction.

Turned out it was a leaking petcock. It's Certified so the warranty covered it. I also reported the steering wheel was squeaking and they ended up replacing the steering rack. Steering feels much lighter and smoother now. Plus my trunk needed a new seal. Window needed a new switch. So glad everything was covered!

[cajun1le]

Nice find! Which one (radiator or engine drain)?

[yescats]

Originally Posted by cajun1le

Nice find! Which one (radiator or engine drain)?

Radiator