My transmission barely moves the needle at all, 140 maybe 150. Just running around town it never goes off the 140. If I am working it hard maybe 180. this is an Auto Meter gauge. I had another gauge with a different sensor and it did the same. The Auto Meter sensor is in the deep pan. Would my heat exchanger be plugged so that it doesn't heat up the trans fluid once the engine is at operating temperature?
Please give me some ideas.

Thanks

 

Temperature readings depend greatly upon where the temperature sensor is located. Ambient air temps can have an effect, too. Your unloaded temperatures are somewhat warmer than mine, but you also have a heavier truck and taller gears, so I suspect that would be more heat in the trans. For non-towing driving, with the sensor in the bottom of a deep pan, I'd say your readings are not abnormal. If your heat-exchanger was plugged, I think you'd be seeing higher temperatures.

 

If the heat exchanger or the trans cooler are plugged on the trans fluid side your transmission will act up completely. Bad shifts and lockup problems from the first second, torn up bearings and planetaries after minutes.
Oil temp probe in the pan isn't ideal. You can get a line with a bung for a temp probe, this measures output oil temp before cooling.

 

I also prefer having my sensor in the output line from the transmission.

 

I use a Westach dual temperature gauge. One side is fluid temp coming out of the trans & the other is in the pan.