Jeep Trany Cooler Mod

One of the reasons I bought my Jeep Wrangler Unlimited was to pull an enclosed trailer loaded with two 1000 LBS+ Harley-Davidson's to places warmer and more scenic than Chicago.  The Jeep is technically rated to tow 3500 LBS, but in the real world the transmission will overheat when pulling a full load -- especially up hill at highway speeds.  Chrysler Corp doesn't sell an add-on Transmission Cooler for the Wrangler, so I had to improvise.

I purchased a B&M 70268 SuperCooler from Summit Racing.  The kit comes complete with most parts needed for an average install; however, I had to buy a few extra pieces to tweak it to fit into the Jeep:

• 4 1/2" long 1/4" bots (the ones that come in the package a bit too long.  I was able to use the nuts and lock washers that came with the kit.
• 2 3/8" to 3/8" Hose Barb Connectors purchased at Home Depot.  Similar to these with 3/8" barbs on both ends. They sell these in the pluming section of the store. 
  
• 2 additional standard ring hose clamps.  The kit comes with connectors that have barbs on one end and screw connectors on the other.  They are a bit too big for the Jeep.  The couplers make the job cleaner. 
• 1 bottle of Mopar certified Synthetic ATF-4 Transmission oil.  The cooler will take up a bit more than 1/2 of a court.  

The first step is to remove the grill and expose the radiator:

The next step is to identify the mounting location.  Jeep actually makes this job pretty easy.  Along the top of the radiator there are two plastic mounting plates that work perfectly.

As you can see, the top mounting points are a piece of cake.  The bottom is easy enough, but it does require drilling the crossbar.

Here's what it looks like after all 4 brackets are mounted:

The next step is the scary one.  I had to cut into the stock transmission oil cooler lines.  The oil lines run from the drivers side behind the radiator and then to the rear.

Using a tubing cutter I cut the top tube in the center of the hose:

 

I then routed the lines going to/from the Oil Cooler and tied them into the factory lines.  The critical step is to make sure the oil going into the cooler enters from the bottom hole and exits from the top.  The reason for this is so the oil completely fills the cooler to get maximum cooling efficiency.  The factory top line is the return from the stock oil cooler, so the oil is flowing from the front to the rear.  Using the 3/8" to 3/8" Barbed Couplers, I connected the bottom port to the line coming from the front of the Jeep and the top line to the side going toward the rear.  I wire tied the hoses to secure them to the Jeep:

 

The last step was to get the engine to operating temperature, check for leaks and add ATF-4 Transmission fluid in small amounts through the transmission dipstick hole.  It is critical to add SMALL amounts and check frequently than to add too much.  The transmission can be damaged if it is overfull and it is very difficult to remove oil.  It took me 20 minutes to do this step and I stopped before it was full.  I'm going to drive it a few days and check again to make sure.

Here's the final product: