Transmission cooler install::

Copyright 2006

*All things shown or advice given on this write up is to give you ideas of what can be done. They may not be suited to your vehicle, or your level of skill or even legal in your State or country. I do not endorse any modification/repair shown on this site. You assume all responsibility for any modifications/repairs that you make to your vehicle, and must understand the consequences of each modification/repair you make. I cannot be held responsible for your interpretation of these articles, or your implementation of these modifications/repairs. Anyone who does not have the proper training or background in automotive work should not undertake any mechanical project without proper supervision and instruction. I accept no responsibility or liability for incorrect part numbers, torque values, or any other information. It is advised that any information presented should be verified with official or expert sources. It is up to you to make sure anything shown needs engineering approval or advice before using it. You are responsible for your own actions. *


I was going to be doing some light towing soon and I was planning to take my XJ on to the beach when I went to Ocean City, MD. I figured now would be a good a time as any. I was originally planning on using a stock transmission cooler, but they are a bit too small, and I wanted something larger. I also wanted a plate and fin design as they cool better. However, I did not want to use those zip ties type mounts that go through the radiator. I went to Autozone and found the largest cooler they had. A Hayden 11"x11" for about $70. I believe it was rated for a 10,000 lb truck. Came with a section of hose, some zip tie mounts, directions and a hosing adaptor of some sorts. On my way home I passed Advanced Auto and want to check and see what they had. The had an Imperial brand cooler, 11"x11", for about $50. So I purchased that one and was going to bring the Hayden back to Autozone. Just out of curiosity I compared the two radiators. They were exactly the same, made by the same company.

Next I stopped at my local Ace and picked up something to create a mount with. What I found was a straight piece of flat steel bar. They also had aluminum, but I felt that the flexed too much. Originally I had to planned to use parts from a ZJ transmission hose to attach to the lower stock hose without destroying it. Could have probably found a good used ZJ hose at a salvage yard, but didn't have time for that. Would have been nice, but oh well. However, that proved to be a different size and leaked once hooked up.

If you need to un hook the lower transmission hose from the radiator you will need one of these tools for the disconnect:

So I also purchased some barbed line joiners from Ace along with some hose clamps.

Only two will be needed.


When I had everything at my garage I started to take a look at how to install this cooler. It was too big to actually fit through the grill opening to mount. So, I took the header panel off along with the bumper.. now was a good time to take them to the paint shop and have them repainted (bad paint from previous paint job). The header panel is held on by two bolts on the left and right horizontal sides. One is accessed from the engine compartments, and faces reward, and the other is directly from the lower from of the header panel. At the top, above the upper radiator support there are several bolts as well. The head lamp buckets stay attached to the header panel, so your lights don't go out of adjustment. This also gave me a chance to clean up the wiring for my Cibies and LightForce lamps. After the header panel and bumper is removed we see this:

After about an hour of thinking of where to mount the radiator, how to run the hoses and which way to orient the cooler I decided on the left hand side and run the hoses through the gap between the fender and the radiator.

For mounts I cut off portions of the steel bar I had purchased earlier, heated a part of in until red hot and bent a 90* angle in two pieces using a BFH. I than painted them with high temp engine paint. A few shots of those finished:

Once I had them bent I started to tested fitted them with the cooler. Held the whole lot in by c-clamps.

It would be easy enough to mount it below the upper radiator support and the part of the body behind the bumper. once I had the cooler dry fitted, I marked where I was going to drill holes into the XJ and into the steel rod. I only drilled 3 holes in the XJ for mounting, as there was a factory hole I could use.

Right side hole on upper radiator support: (touched up in silver to cover bare metal)

Left hand side hole on upper radiator support:

Hole in body piece below radiator(anyone know what that is actually called?):, hi lighted in red and touched up to cover bare metal as well:

Fourth hole from the factory:

Here is a photo of the cooler mounted to the mounting brackets with stainless steel hardware:

I used stainless steel hardware as I hate rust.

A photo of the cooler installed:

On the three holes I drilled I used nuts, bolts, washers and lock washers. On the factory hole there wasn't actually a way I could get behind it. So I used a large sheet metal screw. I had drilled the top holes so that the mounts were as far forward under the upper mount as possible.

Picture of the lower hose coming out of the cooler and the sheet metal screw.

I didn't like the how close the new cooler sat to the condenser at the bottom of the cooler. I fixed that by placing a nut on each of the lower mounting points to space it out enough:

Just the right amount of room:

A pic of the upper mount on the underside of the upper radiator support (I later used those clip on nuts):

After the cooler was mounted I ran the hoses behind the radiator. I cut the lower line about 6 inches from where it mounts to the stock radiator and inserted the hose splices and joint the lines with hose clamps. I also used some zip ties to keep the lines out of harm's way. The routing isn't as perfect as I would like it to be, but I don't see any problems with it. I also put a piece of vacuum hose on the fender so the hoses won't wear against the jagged edge. You can barely see that in the photo below:

Let me know if you have any comments or additions.