[DieselShad]

I added a 26K towing tranny cooler to my truck, and so far the tranny has not exceeded 190 deg. The big test will come this weekend when I'll be towing my 34' travel trailer over the Allegheny Mountains in 95 deg heat. I installed the after market cooler in the same fashion as the dinky stock cooler: fluid runs from the front of the tranny to ther radiator, then to the cooler, then to the back of the transmission. I read an article that suggested bypassing the radiator altogether. Makes some sense to me, but is there a good reason to continue to have transmission fluid flow through the radiator? Appreciate the help!

 

[Mark Kovalsky]

It makes sense to run it through the radiator so that the ATF is cooled. You will lose a lot of your cooling capacity if you bypass the radiator.

Most people seem to think the radiator heats the ATF. That's NEVER true. I've tested it in ambient temperatures from -40° to +115°F and could not find a condition where the radiator was warming the ATF.

The radiator cooler is in the part of the radiator where the coolant has already been cooled by air flowing over the radiator. The cool side of the radiator is anywhere from 15 to 100+ degrees cooler than the engine temperature, depending on load, RPM, etc.

 

[DieselShad]

The bigger radiator cooler suggested by mjonesjr with the fluid routing confirmed by Mark Kovalsky worked great. Despite record high temps in the Mid Atlantic region, tranny temp never exceeded 195 degrees while towing 7K + trailer in the mountains. I hate to think what might have happened to my transmission without the temp gauge and bigger radiator cooler. :ack: Thanks for the advice!