Coolant temp goes up after I turn my car off but back down after i turn it on

[derek2079]

My Coolant temp in my car goes up a little bit after I leave it parked somewhere for 10-15 minutes then back down after I start it up and let it idle.

[DieselElectric]

This is normal.

When the engine stops the coolant is no longer circulated through the radiator, so the water in the block just sits and collects heat. Then when you start it up, the hot water moves from your block, past the coolant temp sensor, and your temp gauge raises until the cooler water from your radiator moves in.

[JordanBetch]

^ could not have said it better.


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[derek2079]

This is normal.

When the engine stops the coolant is no longer circulated through the radiator, so the water in the block just sits and collects heat. Then when you start it up, the hot water moves from your block, past the coolant temp sensor, and your temp gauge raises until the cooler water from your radiator moves in.

Appreciate you. The same thing happened on my a4 a long time and now I know why.

[MacDaddy]

This is normal.

When the engine stops the coolant is no longer circulated through the radiator, so the water in the block just sits and collects heat. Then when you start it up, the hot water moves from your block, past the coolant temp sensor, and your temp gauge raises until the cooler water from your radiator moves in.

That is true but it shouldn't lnt be enough to notice on the temperature gauge, ive never seen that on my car and although i may not live in the hottest climate we will have a few days a year it gets up to Southern California temperatures, especially inland. Im going to venture to say his car is running hot AF but enough for the display to show it as normal.

Op, what are your oil temps like? Ive found that to be a better indication of a bad thermostat or engine running hot

[rpallen85]

Mine does the same, I run 225 oil temp and coolant temp dead center. I turn it off, pump gas, turn it back on & it is slightly warm on the coolant side, about 30 seconds of driving it is back down to normal.

I mainly track my car, after a session the oil temp is around 275 & the coolant one tick passed center. After a session I run the motor, hood up for 15 minutes or so & it cools completely.

What I am saying is there may be some underlying issue, but my car has seen extreme temps without any ill effects.

[AvantGuard]

It's normal - worry no more.