Trans Temp increase in 4x4 when parked

[Mescareno]

New to site and first time owning a truck. Unsure if this is normal or not

 

2012 GMC Sierra 1500 Crew Cab 4.8L 4x4

Truck runs at about 108 degrees for normal running transmission temp when in 2x4 which is low from what I am reading. When I put it into 4x4 temps jump to 150-155 degrees. Today when parked in 4x4 temps starting increasing into the 180 range and only had it in 4x4 for maybe 1 mile. I turned off the truck to let it cool down and put it back into 2x4. Temps started to drop down to the 140 range. Is this normal for both my normal running temp of 108 in 2x4 and fast increase when in 4x4?

[CamGTP]

I've never personally tried to watch my transmission temps when in 2WD and in 4WD, mainly because I leave the truck in 4AUTO if it's snowing.

 

But it does make sense that the temps get higher because the engine/transmission is working harder with 4WD engaged. I wouldn't be worried at those temps at all. Unless you are seeing 215-220+ on the regular basis in 4WD, there is nothing to worry about.

 

I can barely get above 100-110 degrees in my short commute to work in the winter time. Takes long trips just to hit 130's right now.

[Gray Fox]

You have got to remember when you are not moving you are not getting the airflow across the coolers so that may be some of the issue. 
 

I was always told about 100 degrees over ambient is normal temperature under normal driving. 

[RubiconJoey]

On 1/8/2021 at 7:41 PM, Gray Fox said:

You have got to remember when you are not moving you are not getting the airflow across the coolers so that may be some of the issue. 
 

I was always told about 100 degrees over ambient is normal temperature under normal driving. 

This is likely what you're experiencing. I hauled an enclosed trailer from KY to VA and noticed exactly this as I was monitoring the trans temps. When I was driving on the interstate, temps would be fine. As soon as I got off an exit to get gas/food, the temps would start to rise. On short fuel stops, the temperature would actually be higher after I restarted the truck to leave. This is because the fluid where the sensor is located, was absorbing the heat from the trans. Temps never got too hot but, it was interesting to watch them rise and fall with vehicle speed and the fan kicking on and off. What was really wild was watching how quickly they dropped when it started raining.