2020 Expy Overheating at Highway speeds.

[Password]

It's worth changing the thermostat even if it's not the culprit. I don't know what my engine temps were, but the trans would get to 205-212 driving on the highway 70+mph. It jumped to 255 one day. Changed the t-stat and temps haven't hit over 200 under the same conditions.

 

[SyndicateZ]

Doe the t-stat on the engine also control transmission temps too?

 

[JasonH]

Doe the t-stat on the engine also control transmission temps too?

My recollection is that on the 4th gens, the transmission cooler has a heat exchanger that dumps heat from the transmission into the engine coolant. I'm sure someone will provide a correction if that wrong.

 

[slow3v]

My recollection is that on the 4th gens, the transmission cooler has a heat exchanger that dumps heat from the transmission into the engine coolant. I'm sure someone will provide a correction if that wrong.

This is correct.