can a transmission be too cool?
My 2014 Ram 2500 Cummins Diesel with 68rfe auto trans overheats in traffic especially while towing heavy. There is an aftermarket transmission cooler thermostat delete part which makes the transmission much slower to warm up and run about 30 to 50 degrees cooler than normal (170*F). Will this harm the tranny or is it there to save a little mpg? I see that most transmissions are designed to run at 170*F. Thanks for any input.
"thermostat delete part"
All the thermostate deletes I heard of delay the transmission warm-up = prolong the process of its getting to its working temperature, but do not (and have no means to) influence this working temperature in itself. Since the thermostate is not a cooling or heating device - it is (just) a flow limiter. Once it is fully open, which happens soon after you started driving (and which equals a thermostate delete) - that is it: from this point forward, it has zero influence on the temperature. So you may want to double-check if it is not a marketing lie that your delete makes the transmission run about 30 to 50 degrees cooler than normal. Maybe it does make this difference for a couple of minutes right after startup - but not always. Or does it also do taxes?
BTW running on too cold ATF is not good for the transmission - that is why they actually install thermostates to have this fluid reach the correct temperature ASAP.
Could it be that your thermostate is just out of order and needs to be replaced, and that is it? A malfunctioning thermostate can indeed cause overheating.
If it is OK, what you need is not a thermostate delete, but a larger ATF cooler, or smth to blow more air through the existent one as the ATF gets too hot.