Added transmission cooler (I thought)

Tyandkate wrote:
I brought my truck in for a oil change and transmission service. While in I decided to have them add a external transmission cooler. So I got the call it was ready. The shop installed a NAPA rapid cool transmission cooler I’ll post a link to it at the bottom of the post here’s my concern.
The cooler was installed in the front of the radiator with a direct path of air. But they bypassed the transmission cooler built in to the radiator. Is this okay or is this going to be a issue while towing? Seeking advice from someone that has more knowledge on the subject. Thanks so much for the advice in advance.

The cooler is 11” wide by 9 1/2” tall 3/4” thick
https://www.napaonline.com/en/p/ATP17510

That little pea shooter?



Way too small to operate without the fluid going through the radiator, it will never remove enough heat all by its' self.

It is just one size larger than Haydens smallest 676 which is for CARS.

To run solo, you would NEED a much bigger cooler, something like Haydens 1260 which is 12"x24" or 1290 which is 18" x 24".

Your radiator cooler has infinitely MORE cooling capacity than your small cooler, therefore to use the small cooler it MUST be connected AFTER the radiator oil cooler.

Per Hayden HERE

"Q. Should the cooler be installed before or after the radiator?

A. Hayden recommends installing the auxillary cooler after the radiator to return the coolest fluid directly to the transmission. Installing the cooler before the radiator will still provide additional cooling and may be necessary in some difficult access applications.

Q. Can you over cool the transmission fluid?

A. Transmissions are not highly sensitive to cool operating tempuratures. However, in sub zero (20-30 F) weather conditions transmission fluid can actually gel up in an external cooler and cease to flow, causing damage. Use of the radiator cooler actually helps warm the fluid under these conditions. It is critical in extreme conditions to use the original equipment cooler in series with the auxiliary cooler and allow vehicle to warm up before driving."

The reason for this is the hot oil goes into the radiator cooler, gets cooled to the coolant temp AT THE BOTTOM of the radiator which IS cooler than the top of the radiator.

Then the oil goes through the small cooler dropping the oil an additional 10-30 degrees or so depending on outside air temps and the speed of air going through the cooler..

Every one of my trucks I have owned which have a FACTORY installed aux transmission cooler has the oil routed through the radiator and THEN to the aux cooler.