Transmission Cooler Install with pictures

When I was researching doing a tranny cooler install I found lots of good threads but none with good photos of the plumbing, so I took a few and hope maybe this thread will help someone else ready to tackle the job.


Materials:

• Junkyard tranny cooler from Ford Explorer
• 6 hose clamps
• 2 unions
• 7 feet of 3/8" transmission line

The install for me required, on my 2001, to remove the entire facia. I mounted the cooler first, by bending one of the tabs on the cooler to mount to the top of the radiator support, and then drilling into the bottom support to mount the bottom tabs.


The top line is the return line going from the cooler back to the transmission with the cooled fluid. The bottom line is attached to the line going out of the bottom of the radiator with the hot fluid.


This photo shows the hot line that runs out of the lower radiator. The line covered in braiding is the original soft line that used to connect to the hard line that ran back into the transmission. The portion of the soft line in the braid is connected to a short hard line (not visible behind the steering gear box) that is screwed into the lower radiator. I spliced and connected with a union and 2 hose clamps. This hot fluid leaves the radiator and flows into the lower port of the transmission cooler.


This next photo shows the return line. The soft line that is attached to the hard line, to the right of the joint is the original return line and was under the braiding on the previous photo. I unioned in the return line and the cooled fluid flows out of the top port on the transmission cooler and into the hard line which takes it into the transmission.

This final photo shows how the lines are routed behind the bumper. I brought them down behind the bumper and through two of the factory holes that were in the body.

The line with the blue arrows comes down from the top port of the transmission cooler. I routed it along the inside of the body. It eventually wraps around past the steering gear box and junctions in as part of the last photo on the previous post.

The line with the red arrows takes the hot fluid from the junction in the 3rd photo in the previous post and is routed and ziptied to a hard line just under the oil pan. It runs through the hole in the body to the lower transmission cooler port.

(The dirty piece of metal in the foreground is my sway bar.)





I'm kind of seeing why there were few threads with plumbing pictures. It is pretty hard to get the whole view from under the Jeep.

I hope that this write up made a little sense and might help someone else. For reference the flow of transmission fluid is as such:

• out of lower radiator
• through hose into lower port of transmission cooler
• out of upper port of transmission cooler
• through hose into hard line back to transmission

One question you might have...did it help?

Why yes, yes it did. I took identical drives of about 16 miles (8 on highway and 8 on back roads) before and after and then took temps with an IR thermometer.

Before temps: Transmission pan 180 degrees, transmission 196 degrees
After temps: Transmission pan 155 degrees, transmission 166 degrees

Nice install

Some suggestions:

When possible, use hard line instead of hose. Use hose only for making short connections or where the connection needs to flex. At the line ends, use a double flare to create an obstacle to the hose clamp sliding off.

In the photo where you spliced on to an existing hard line/hose connection. If you cut off that factory crimp with a cutting wheel (The long way, and a shallow cut finished with a needle nose), there is a nice flare under it that you can slide your hose over and clamp the line.

A very nice install and very good writeup and photos.

However, I also have a 2001 and these statements do not match what I found:
"The bottom line is attached to the line going out of the bottom of the radiator with the hot fluid."

"the flow of transmission fluid is as such:

• out of lower radiator
• through hose into lower port of transmission cooler
• out of upper port of transmission cooler
• through hose into hard line back to transmission"

When I hooked up my cooler I believed what I read on other posts, and connected it the same way you did. However, I wanted to be sure the cooler was completely flushed, so I routed the hose that was destined to be hooked to the top of the radiator and instead ran it to a collection bottle. I was standing in front of the Jeep holding the hose in the bottle. I had my wife start up the engine and waited for something to go into the bottle, but nothing did. I waited about 5-7 seconds then had her shut it off -- something was obviously wrong. I then looked in the engine compartment and saw to my dismay that the ATF had shot out of the TOP radiator fitting and splattered on the brake booster housing and then dribbled, ran, and generally made a complete mess of the driver's side of the engine compartment.

What a mess! The V-channel of the LCA was completely filled with ATF, as was the spring bucket, the top of the jounce stop column -- it took over a week of mopping up, driving around, mopping up some more, and leaving the Jeep parked in various tilted attitudes before it stopped leaving spots.

On my 2001 XJ the hot ATF is fed into the bottom radiator fitting and comes out of the top fitting before going back to the transmission.

Have you actually checked to see which way the fluid is flowing in your system?

It looks as if the fluid is traveling "up" the cooler instead of flowing down..

I ran my lines straight from the trans to the cooler. I ran the flow top in bottom out on mine. I figured it would be easier on the pump to let gravity do some work.

Supposed to be bottom in, top out so no air gets caught in the cooler I believe.

sunburned said:

Supposed to be bottom in, top out so no air gets caught in the cooler I believe.

Click to expand...

Correct. It's also so the cooler 'fills up' with fluid from the bottom instead of draining down from the top and not utilizing the full potential of the cooler.

http://bmracing.com/wp-bnmcont/uploads/bm_cooler_techdoc.pdf

Lurch said:

Correct. It's also so the cooler 'fills up' with fluid from the bottom instead of draining down from the top and not utilizing the full potential of the cooler.

http://bmracing.com/wp-bnmcont/uploads/bm_cooler_techdoc.pdf

Click to expand...

Interesting..
Guess it makes sense

what if you bypass the radiator, does it matter at that point? seems like the loop would be the same.

djlarroc said:

what if you bypass the radiator, does it matter at that point? seems like the loop would be the same.

Click to expand...

If you're asking if the flow should still be bottom up, then yes. That's just how the cooler works most efficiently.

If you're just asking if you can bypass it, yes you can, but in cold climates, the fluid can benefit from being warmed up by the coolant.



I just saw that the OP sourced a junkyard cooler. It looks exactly like the B&M cooler that I have.

sunburned said:

I just saw that the OP sourced a junkyard cooler. It looks exactly like the B&M cooler that I have.

Click to expand...

Ford Explorer - $10 at the Pull and Save

sunburned said:

If you're asking if the flow should still be bottom up, then yes. That's just how the cooler works most efficiently....

Click to expand...

Yes, that is what i meant.. if you bypass, if there is still a certain way on running the hoses. If you access the lines right by the oil pan for example, how do you know which line is which, and if it goes into the top or bottom on the cooler. (Sorry for the thread jack).. just curious for it comes to install.

djlarroc said:

Yes, that is what i meant.. if you bypass, if there is still a certain way on running the hoses. If you access the lines right by the oil pan for example, how do you know which line is which, and if it goes into the top or bottom on the cooler. (Sorry for the thread jack).. just curious for it comes to install.

Click to expand...

On my 2001 the line that connects to the bottom of the radiator carries ATF from the transmission to the radiator. The line that connects to the top of the radiator carries ATF from the radiator to the transmission.

You should do the same with your cooler -- the bottom of your cooler is just like the bottom of the radiator. In other words, if you are bypassing the radiator and replacing it with your cooler, take the line that currently connects to the bottom of the radiator and connect it to the bottom of your cooler. Take the line that currently connects to the top of the radiator and connect it to the top of your cooler.

djlarroc said:

Yes, that is what i meant.. if you bypass, if there is still a certain way on running the hoses. If you access the lines right by the oil pan for example, how do you know which line is which, and if it goes into the top or bottom on the cooler. (Sorry for the thread jack).. just curious for it comes to install.

Click to expand...

For all years - look at the tranny. The line at the front of the tranny is the "out" line from the tranny. The line at the rear of the tranny is the "return" line.

Edit: I always run into the bottom of the cooler and return from the top fitting.

thanks for the clarification guys!

Sorry to revive an old thread here. What year explorers work best for this?

The second generation ('95-'01) with the 4.0L. When I did this mod, I had to trim the fiberglass nose piece and black plastic grill a little, but it was no big deal. Quick work with a Dremel.

Just to let you all know, apparently early Cherokees like my 1990 4.0 liter run the tranny fluid into top of radiator side tank, later cherokees like my friends 2000 4.0 liter run the fluid into bottom of radiator side tank. sometime between 1990 and 2000 jeep reversed the fluid flow thru the radiator. Be aware of this, check your hose routing. the front most fitting on tranny is outlet, rear most is inlet AW4 tranny.