I was thinking of adding a auxiliary transmission cooler, due to my average trans fluid temps being 190-200 degrees. This is the average temp while driving down the highway and normal highway speeds, not towing anything and no load in the bed on relatively flat ground. So my question being, sure the cooler would be fine in the summer time on a 100 degree day, but what about in the winter time on a 30-40 degree day? Can I over cool the transmission? Will over cooling the transmission harm the transmission or fluid? I don't want to fix one problem, but create another.

 

I don’t think you’ll over cool in the winter. What about the trucks that come with a transmission cooler from the factory. You’ll be OK

 

My truck does have the factory transmission cooler / tow package. I can't imagine how hot it would be with out it.

 

The only time you can overcool it is if it doesn't reach the minimum temperature to allow it to shift into OD and allow the converter to lock.

 

What temperature would that be? As it is now, on cold winter days it averages about 150 degrees. I want my temp to be below 175 in the summer but still within operating range in the winter.

 

This is the cooler that I was looking at...
http://store.summitracing.com/partde...part=BMM-70297

Also, I was planning on adding a filtration system for the transmission at the same time, one just like this...
https://www.f150online.com/forums/sh...d.php?t=290659

Along with a full flush of new ATF. I got a case and a half of Valvaline full synthetic ATF Mercron V at my local O'Rilies for $56. The Mobile 1 ATF was $8/quart and the Royal Purple was $11/quart. hopefully the Valvaline will work just as well... even though I would have liked the others, the Valvaline was priced right...

 

sorry, it double posted the above...

 

Does yours not have a cooler bypass valve on it? I know mine does, it doesn't allow the fluid to flow through the cooler until it reaches a certain temp. So you should be perfectly fine.

I was thinking about putting in a larger cooler myself because I was towing through hills today and my temp was getting around 220, I had to stop for a bit and let it cool. That was mostly uphill tho, on level ground it was about 185-195.

 

OK, this may be a stupid question, but: How are y'all reading the exact temp. of your trannies?

 

By adding an aftermarket tranny temp gauge.

Yes...you can not 'overcool' a tranny on a '04-newer truck. They have a thermostat in the lines that run to the cooler which simply returs the fluid straight back to the tranny until it is up to a certain temp. No, I don't know what the temp is.

 

Oh!

 

Thanks! Thats what I needed to know! The bypass will regulate the temp until it gets too hot, then sends the fluid to the cooler.