Engine warmed up, then went cold.

[1slofofo]

Today I was sitting on break in my car, and after it warmed up, put the heat at like fan speed 2, and after a minute or two, I see the engine temp gauge slowly drop back to cold. It didn't go all the way to cold, I turned off the heat, and it climbed back up.

Should I be worried that this happened? To be fair, it's been below freezing around lately. Anyone else experience this?

[Deftmetal]

I've noticed that just idling mine doesn't heat up that fast. Also that trying to make it warm inside quickly just keeps the engine cool

[1slofofo]

I've realized that, too. Which is why I wait until the engine says it's warm on the gauge. But mine went backwards...

[suss6052]

Originally Posted by adamdv5

I've realized that, too. Which is why I wait until the engine says it's warm on the gauge. But mine went backwards...

The car says its warm on the gauge well before the engine is actually warmed up. Its more of a dummy gauge, so unless you were to have been checking in test mode the temperature sensor reading you wouldn't know that it reads 50% (aka nominal) as low as 41C or sooner which is still frozen in terms of engine temperatures. Normal operating temperature is actually closer to 80-97C when its fully warmed up.

It doesn't warm up all that fast when its cold, especially if you don't have the heater set to maximum for long enough to trigger the active shutter system to close and warm the engine up faster rather than sucking in cold air.

[thejordan]

Thermostats open when hitting a certain temperature (150-180F for most cars), and fans kick on and off as well, which all act to cool the engine, especially at idle. Running the heater acts as an additional source for heat removal so the thermostat doesn't have to open as often.

[Dark 007]

Originally Posted by adamdv5

Today I was sitting on break in my car, and after it warmed up, put the heat at like fan speed 2, and after a minute or two, I see the engine temp gauge slowly drop back to cold. It didn't go all the way to cold, I turned off the heat, and it climbed back up.

Should I be worried that this happened? To be fair, it's been below freezing around lately. Anyone else experience this?

I'm from Chicago as well. I completely understand, It's been brutal out here lately, you know. My car does the same exact thing, it's an 01.


Posted via iPhone using FF Mobile

[Elizabeth]

Originally Posted by thejordan

Thermostats open when hitting a certain temperature (150-180F for most cars), and fans kick on and off as well, which all act to cool the engine, especially at idle. Running the heater acts as an additional source for heat removal so the thermostat doesn't have to open as often.

Agree. With a cold engine. the thermostat is closed until the coolant warms up in the engine enough to open the thermostat. then all that hot coolant flows out to the cold radiator, and the engine is cooled by the incoming cold coolant.
So it would be natural in cold weather for the heat to fluctuate some untill the system reaches a steady state.

[Bogey]

Your heater is just acting like a radiator cooling your engine , especially if its cold out. Happens all the time in the great white north thats why when we start our engines if its cold to turn off the heater until it get warm.