Started to overheat while idling parked

Tiny
VICMARMIL
  • MEMBER
  • 2002 CHEVROLET MONTE CARLO
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 112,000 MILES
The temperature gauge bottoms out then goes back up then down while driving. If I am stopped at a red light, when light turns green it occasionally shuts off. I was idling while waiting on a friend and it began to overheat. No lights came on, no engine or coolant light. I could feel that liquid popping and shut it off before it steamed.
Thursday, November 21st, 2019 AT 2:05 PM

18 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good afternoon,

Did you check and see if the cooling fan was working?

https://www.2carpros.com/articles/replace-electric-fan-motor

How old is the thermostat?

https://www.2carpros.com/articles/replace-thermostat

Did you verify the coolant level?

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Roy
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Thursday, November 21st, 2019 AT 3:12 PM
Tiny
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I ran the heater and the temperature came down. The temperature gauge has been fluctuating for the past week between normal operating temperature and 0. I did not notice any odor at the time it was too hot or after driving with the heater on.
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Thursday, November 21st, 2019 AT 3:19 PM
Tiny
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Okay, got it.

All my questions still stand.

Roy
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Thursday, November 21st, 2019 AT 3:22 PM
Tiny
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I do not know the age of the thermostat because I bought the car less than 6 months ago. I do believe the fans are fine and no fluid leaks. I did add some water just to get home. Should I drain the system and replace fresh coolant as well as get it diagnosed?
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Thursday, November 21st, 2019 AT 3:27 PM
Tiny
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I would replace the thermostat, add new coolant and drive the car and see if it is fixed or if it still has issues.

Roy
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Thursday, November 21st, 2019 AT 3:29 PM
Tiny
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Because no warning light came on, I am thinking that some fuses might also need to be replaced?
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Thursday, November 21st, 2019 AT 3:31 PM
Tiny
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Should the coolant be drained completely?
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Thursday, November 21st, 2019 AT 3:33 PM
Tiny
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No, since you said the fans are working, it is not electrical.

Yes, remove the lower hose to get it all out.

Roy
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Thursday, November 21st, 2019 AT 3:45 PM
Tiny
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Was that no to the fuses? Shouldn't my temperature warning light have come on?
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Thursday, November 21st, 2019 AT 4:23 PM
Tiny
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No to the fuses. When it gets very hot, there will be a warning but that is not the reason for overheating. It is just a warning.

Roy
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Thursday, November 21st, 2019 AT 4:27 PM
Tiny
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I understand that the fuses have nothing to do with overheating.
Totally separate issue. My concern being that the dash lights are supposed to warn me of engine trouble and/or temperature problem and they did not.
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Thursday, November 21st, 2019 AT 4:46 PM
Tiny
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Okay, that could be the coolant sensor that sends a signal to the ECM to turn on the warning light as well as making the gauge readings correct.

Roy
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Thursday, November 21st, 2019 AT 4:52 PM
Tiny
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  • MEMBER
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Is the coolant sensor related to why the temperature gauge on my dash kept dropping then going back to normal?
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Thursday, November 21st, 2019 AT 4:57 PM
Tiny
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Yes, it is. It most likely is reading correctly since the cooling fans were coming on as the temperature got too high.

Roy
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Thursday, November 21st, 2019 AT 4:58 PM
Tiny
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Okay, so I likely am looking at replacing thermostat and coolant sensor and drain and flush the cooling system?
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Thursday, November 21st, 2019 AT 5:01 PM
Tiny
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As a start, yes. Replace them and see what happens.

Roy
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Thursday, November 21st, 2019 AT 5:04 PM
Tiny
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Thank you Roy. You have been very helpful.
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Thursday, November 21st, 2019 AT 5:06 PM
Tiny
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You are welcome.

Always glad to help.

Roy
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Thursday, November 21st, 2019 AT 5:08 PM

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