I recently purchased a larger travel trailer and when towing with my 99 expedition (with tow package), my transmission temperature was running between 210 and 220 F (sensor installed in test port of transmission). This is a little higher than I like, so I decided to install a larger transmission cooler. I thought other people may benefit from experience so I took plenty of pictures. While installing the larger cooler, I took the opportunity to service the transmission (drain pan and torque converter, replace filter and fluid).

I decided on the B&M cooler 70266. It is rated at 20,500 BTU. However, I do not know the rating of the stock transmission cooler, so I based my choice on the fact that this cooler is the same type (plate) but twice as tall as the stock cooler. The stock cooler is only about 4 inches tall while the B&M cooler is 8 inches tall.

The first thing I did was drain the transmission pan and the torque converter. Below is a picture of the transmission (pan removed) and the filter.




Below is a picture of the pan with the dirty magnet before I cleaned it:



The next picture shows the magnet after I cleaned it:



My next step was to remove the stock cooler. It is located in front of the radiator on the passenger side of the vehicle. Below is a picture of the stock cooler looking at it from the top (must remove a black plastic piece to see into the area in front of the radiator). It is held on by one screw on the bottom of the cooler and a screw on both the left and right sides of the cooler. All three had easy access.



The next picture shows the area in front of the radiator with the stock cooler removed. There is plenty of room to mount a larger cooler:



The stock cooler is mounted with the fittings pointed downward (to the ground) but the B&M installation instructions said to install the new cooler with the fittings up or to the side. I decided to follow the instructions which meant I would have to run hose from the existing supply and return lines up to the inlet and outlet fittings of the new cooler. This seemed easy enough except that I could only break loose the outlet line from the stock cooler. I could not break loose the supply line to the stock cooler. I was afraid to put a lot of torque on the fitting because the whole stock cooler was beginning to twist plus I didn’t want to damage the existing lines. Both supply and return lines have a short section where instead of tubing the line is hose (maybe about 4 inches long) not far from the stock cooler. I decided to cut both lines at this tubing and use hose barbs to connect my new lines that would run to the top of the new cooler. After I cut the lines, I could easily remove the stock cooler. Below is a picture of the stock cooler next to the new cooler:



I decided to use L-brackets to mount the new cooler. I purchased L-brackets from a local hardware store and used a hacksaw to cut them to size. I then drilled a 1/4 inch hole in each bracket and used a bolt and nylon lock nut to attach the bracket to the new cooler. I attached 2 brackets to the bottom of the cooler and one to the top passengers side of the cooler. I could not find an easy place to attach a bracket from the drivers side of the cooler to the truck without trying to make a fancy bracket. Below is a picture of the new cooler with the brackets attached. The picture also shows the 1/2 inch NPT hose barbs mounted into the cooler (these were purchased at a local brass and hose manufacturer):



I attached the bottom brackets to the pan that runs below the radiator. I drilled 3/16 inch holes in the brackets (you can see them in the photo above) and 7/32 inch pilot holes in the radiator pan. In the process of drilling, I discovered I’m not very good at drilling holes in the correct location. I had to re-drill several holes because they did not line up with the bracket holes. I used #12 x 3/4 inch sheet metal screws to attach the brackets to the radiator pan. Below is a picture of the bottom of the radiator pan with the pilot holes (picture taken before I had to re-drill). Again, you can see the existing transmission hose that returns to the transmission with the hose barb installed.



The upper passenger side bracket was attached to a column that ran top to bottom just to the left of the radiator. The picture below shows the upper passenger side mount.



For the top driver side mount, I simply used a cable tie from the cooler flange to a center support in the truck. The picture below shows the cable tie along with the supply line attached to fitting:



After this, the rest of the install went pretty easy. I attached transmission hose from the top of the new cooler to the hose barbs on the existing lines and used clamps to secure. I also used cable ties to secure the hose. The following pictures show the final install.

Install from the top:



Install from the bottom:



After this, I filled the transmission with Mobil1 synthetic (15 quarts @ $10/quart hurts). So far, nothing has leaked. I keep checking all the screws and bolts to make sure nothing is loosening up.

I can't give any temperature numbers because I have not towed my trailer. We have a trip planned to Florida in August, so that should be a nice test.

 

Man. Luv the details. I'm thinking of doing something similar. Did you ever get a temp reading after you install the new cooler?

 

Excellent write up!

 

Very good write up! Reps sent. I suggest that you check on that one hose shown in the last pic as it looks like it may have a chance wear due to vibration and rubbing on the sheet metal there.

 

Nice work, thanks for the detail and photos.

I am not a fan of standard cable ties in a hot, critical environment - they degrade and break when you least expect it. Keep an eye on them.

 

I just happened to run across this old post of mine and thought I'd give an update. I've had no problems or leaks with the transmission cooler. I did take the advice of Moto Mel and put some black plastic protector around the hose. Also, as Boat Tug suggested, I check the cable ties occasionally.

I've towed to Florida twice and Charleston, SC once. All three times in a hot August. Transmission temperatures ran between 190 and 195 F. Expedition now has 195k miles on it and is still going strong.

 

$150 for fluid, yikes!!!!

I always mount my coolers hose down with no issue, you can run the engine once with the cooler tipped if youre worried about trapped air. Also, Home Depot carries the NPT to barb connectors as an FYI.

 

I have that cooler on my 4runner, hell to get in due to how large it is, but I consistently stay below 190 even when I'm out off-roading...great cooler.

Though the downside is it doesn't have the low temp bypass like it counter part from Tru-Cool.

 

Synthetic is definitely more expensive the regular fluid.