Transmission Cooler Leaking

lanthony2020 · **Joined:** Sun Feb 09, 2014 11:52 am **Posts:** 27

Hello, just had elbow surgery. Please bare with. Is the tranny cooler and AC condenser a one piece unit here? Where to get one. How hard to install? Mine is leaking fluid pretty badly.

THX
Lex

P.S How about a tranny stop leak?

dieselguy · **Posted:** Thu May 29, 2014 11:51 pm

lucas makes a good transmission additive and it will stop small seal leaks but nothing big. I use it in everything I own and throughout the years have put hundreds of thousands of miles on my vehicles. I use lucas additives in engine, gear cases and trannys. I have had hard shifting transmissions and add a bottle and almost instantly saw a difference. don't get me wrong its not gonna rebuild a worn out piece of equipment but it can greatly extend its life.

mass-hole · **Posted:** Sun Jun 01, 2014 12:36 pm

I think a lot of people just bypass the stock trans cooler and add in a stand alone unit with much better heat handling capacity. It sounds like the stock one is notorious for leaking.

dgeist · **Posted:** Thu Jul 03, 2014 3:39 pm

moved to discussion section.

papaindigo · **Posted:** Thu Jul 03, 2014 3:55 pm

On 05 and 06 KJ CRDs at least the tranny cooler is located in the bottom of the AC condenser. The lines to/from the cooler are attached by some sort of fitting that can leak; I believe there are repair options to that. If the cooler itself is leaking the standard option, IMHO, for any such situation is to simply install a good aftermarket tranny cooler right behind the grill and run your transmission lines to there; effectively cutting the leaky OEM cooler out of the system.

Shoot me a PM or email if you want links to several posts on adding a tranny cooler to accomplish the above.

dgeist · **Posted:** Thu Jul 03, 2014 4:04 pm

It's pretty common for the "conjoined twins" to start leaking. Here's the driver's side fitting on mine (viewed from under the grille area):

And a pretty good aftermarket option:
http://www.amazon.com/dp/B000C3DDKO/ref=wl_it_dp_o_pd_nS_ttl?_encoding=UTF8&colid=249J0KR92M1B7&coliid=I3JE9WYCO1L10X

There are several threads on the forum with various models and locations used for the aftermarket solution. The search tool is your friend.

Dan

Topan · **Posted:** Sat Jul 05, 2014 7:39 am

I made the mod to add a bypass cooler, as my stock cooler leaked, like it is the case to most of us.
If you do it, please go for a high quality one as mine seems to not being able to evacuate enough heat.
Here is my write-ip on the mount.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=62013

My cooler is a B&M, very strong but maybe not efficient enough.

dgeist · **Posted:** Sat Jul 05, 2014 9:32 am

Topan wrote:

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=62013
My cooler is a B&M, very strong but maybe not efficient enough.

Topan, I suspect you may not have enough surface area (cm^2) for your climate/terrain (der schweiz has a few more mountains then most places)

Whatever model/brand you choose, the surface area and placement are the most important aspects. As far forward as possible and with the exit at the top (regardless of input) is how you want the flow, and as large as you can fit is what size you want. Thinner cross-sectional models seem to fit better in the front of the cooling stack on the KJ.

Dan

Topan · **Posted:** Mon Sep 08, 2014 1:53 am

dgeist wrote:

Topan wrote:

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=62013
My cooler is a B&M, very strong but maybe not efficient enough.

Topan, I suspect you may not have enough surface area (cm^2) for your climate/terrain (der schweiz has a few more mountains then most places)

Whatever model/brand you choose, the surface area and placement are the most important aspects. As far forward as possible and with the exit at the top (regardless of input) is how you want the flow, and as large as you can fit is what size you want. Thinner cross-sectional models seem to fit better in the front of the cooling stack on the KJ.

Dan

Yes you are right, there are plenty of mountains around here and the trans is working/shifting a lot.
The by-pass cooler is in fact quite we'll expose to air flow and fluid out at the top. Still the trans is overheating.
I tried to add a fan to it but there is not enough space, fans are too thick.
So now that I have replaced the condensor/TOC, I will connect the stock TOC back again as there is a fan on it ( same than air on condensor) . And I will leave the by-pass cooler there but unplugged, just in case.
Am awaiting for the lines connectors from Mopar.

mass-hole · **Posted:** Mon Sep 08, 2014 9:21 am

Topan wrote:

dgeist wrote:

Topan wrote:

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=62013
My cooler is a B&M, very strong but maybe not efficient enough.

Topan, I suspect you may not have enough surface area (cm^2) for your climate/terrain (der schweiz has a few more mountains then most places)

Whatever model/brand you choose, the surface area and placement are the most important aspects. As far forward as possible and with the exit at the top (regardless of input) is how you want the flow, and as large as you can fit is what size you want. Thinner cross-sectional models seem to fit better in the front of the cooling stack on the KJ.

Dan

Yes you are right, there are plenty of mountains around here and the trans is working/shifting a lot.
The by-pass cooler is in fact quite we'll expose to air flow and fluid out at the top. Still the trans is overheating.
I tried to add a fan to it but there is not enough space, fans are too thick.
So now that I have replaced the condensor/TOC, I will connect the stock TOC back again as there is a fan on it ( same than air on condensor) . And I will leave the by-pass cooler there but unplugged, just in case.
Am awaiting for the lines connectors from Mopar.

That seems weird. It's not like the one you added is small or anything. It's gotta be at least as big as the stock one.

Topan · **Posted:** Fri Sep 12, 2014 1:13 pm

Yes , agree, totally weird. The cooler I used for by pass is real large in cmxcm.
But sill , the trans is overheating as soon as I go steep on an off road trail. ( the 'hot trans oil ' light comes out on the dash board)
It started suddenly, never understood why....
Maybe the trans is just tired... :shock:

greiswig · **Posted:** Sat Sep 13, 2014 5:44 pm

Finally got to looking more closely at the transmission cooler. It is basically the bottom 3" of the combination ATF cooler/AC condenser, and about 5/8" thick. Wow. Around 50 whole inches to cool the fluid.

It seems like all the bypass solutions that I see here place a larger cooler, but don't have it mounted under the electric fan. I don't remember if there is enough room, but if there were 3/4"+ extra room, it would be nice to just sandwich another cooler in front of the AC condenser instead, wouldn't it? Then it would have the. Benefit of greater airflow?

geordi · **Posted:** Sat Sep 13, 2014 6:19 pm

This may seem counter-intuitive, but there is about an inch of space between the AC radiator and the main radiator. A narrow but HUGE cooler could fit easily in that space, and then you would have the benefit of BOTH fans helping cool things down.

greiswig · **Posted:** Sat Sep 13, 2014 7:24 pm

geordi wrote:

This may seem counter-intuitive, but there is about an inch of space between the AC radiator and the main radiator. A narrow but HUGE cooler could fit easily in that space, and then you would have the benefit of BOTH fans helping cool things down.

Most aftermarket units seem to be 3/4" thick, so that could work with a good bracket. Thanks, geordi...I'll look into it.

geordi · **Posted:** Sat Sep 13, 2014 8:22 pm

If you really want to be spiffy, get some measurements, and a boneyard AC condenser that matches could be a good option. Just cut off the ends of the hard lines, slide the hose over them and clamp. The AC condenser would be MUCH larger with many more fins than a transmission cooler, so it would transfer more heat away than a regular cooler.

The usual push-through plastic clips for auxiliary coolers are quite fine for mounting, I have used them to good effect on multiple vehicles and never had any problems with them. I believe they are sold separately from the cooler, but you may need to look on Amazon for them if the parts shack doesn't have them.

Topan · **Posted:** Mon Sep 15, 2014 6:59 am

geordi wrote:

This may seem counter-intuitive, but there is about an inch of space between the AC radiator and the main radiator. A narrow but HUGE cooler could fit easily in that space, and then you would have the benefit of BOTH fans helping cool things down.

Geordi, i think it is really a good idea....
i will defintely look B&M or other brands of oil coolers to see if they offer one that could fit into this gap. i dont expect the stock trans cooler (that i just replaced ) to last very long.
But still i will focus on the ones with good airflow, in order to avoid blocking the airflow to the engine.

geordi · **Posted:** Mon Sep 15, 2014 5:23 pm

Airflow to the engine is already excessive, that is why the engine loses temperature when the thermostat fails - the thermostat is the only thing making it get that high.

Sent from my iPad using Tapatalk HD

thermorex · **Posted:** Mon Sep 15, 2014 10:30 pm

I think part of the excessive cooling in the winter is the mechanical huge fan at work. Even if it's not engaged, it still moves a decent amount of air. When I ditched it and installed the ff dynamics e-fan, I haven't had those issues, but still temp drops if left idling for too long. But driving it, it gets faster to operating temps and tends to stay closer than with the viscous.

joelukex4 · **Joined:** Thu Sep 29, 2011 4:54 pm **Posts:** 386

thermorex wrote:

I think part of the excessive cooling in the winter is the mechanical huge fan at work. Even if it's not engaged, it still moves a decent amount of air. When I ditched it and installed the ff dynamics e-fan, I haven't had those issues, but still temp drops if left idling for too long. But driving it, it gets faster to operating temps and tends to stay closer than with the viscous.

Are you happy with the e-fan and are you still using it. Do you even use the fan in winter and does it increase mileage overall?

thermorex · **Posted:** Tue Sep 16, 2014 8:39 am

joelukex4 wrote:

thermorex wrote:

I think part of the excessive cooling in the winter is the mechanical huge fan at work. Even if it's not engaged, it still moves a decent amount of air. When I ditched it and installed the ff dynamics e-fan, I haven't had those issues, but still temp drops if left idling for too long. But driving it, it gets faster to operating temps and tends to stay closer than with the viscous.

Are you happy with the e-fan and are you still using it. Do you even use the fan in winter and does it increase mileage overall?

The most noticeable gain is when driving on Highway. I gained about 2 mpg. I. In the winter, city/highway combined, about 1 mpg. In my opinion it is worth to have. Don't expect though to get the mileage of a golf/jetta tdi, lol. It is a little gain that overall pays for the cost in time. In the winter, I haven't heard the fan starting at all (no towing).

Transmission Cooler Leaking

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