Jump to content

Transmission Cooler Lines


Recommended Posts

I’m finally moving into my transmission cooler lines, as they’ve been leaking constantly because someone did a nasty job while splicing in a transmission cooler. The horrible hose clamp job has led to it leaking ATF and melting the rubber stuff there as well as coating all the metal and wires. I’m sick of it and I don’t need a transmission cooler because I’m not hauling anything with it. What’s the way to go here? da2ce5f4b0e94b380388aa8eed3a15c8.jpg

Link to comment
Share on other sites

I went through this myself and finally replaced the whole system. I used braided an -6 lines along with a moroso tranny oil cooler (has a built in filter and does multiple passes). Converted the whole thing to an fittings and have had zero leaks now. Cost about $400 for the cooler and all fittings but it’s virtually bullet proof now. If you somewhere that gets cold than it is recommended to keep your tranny cooler in the radiator to pre-heat the tranny oil on cold days. You can also run the an lines and fittings with the radiator cooler. Here is a nice write up that I used for some part numbers: http://there4.io/2019/07/17/Jeep-XJ-Transmission-Cooler-Line-Ugrade/

Link to comment
Share on other sites

Just bypass the rad. Run an external cooler and call it good. I've done it on my old XJ and my WJ. I live where it gets cold and never had issues. My WJ has a tranny temp monitor and the other day it was ~20* here, tranny temp didnt get above 125 and it was fine. Hasnt caused issues and historically never had issues. 

Link to comment
Share on other sites

I went through this myself and finally replaced the whole system. I used braided an -6 lines along with a moroso tranny oil cooler (has a built in filter and does multiple passes). Converted the whole thing to an fittings and have had zero leaks now. Cost about $400 for the cooler and all fittings but it’s virtually bullet proof now. If you somewhere that gets cold than it is recommended to keep your tranny cooler in the radiator to pre-heat the tranny oil on cold days. You can also run the an lines and fittings with the radiator cooler. Here is a nice write up that I used for some part numbers: http://there4.io/2019/07/17/Jeep-XJ-Transmission-Cooler-Line-Ugrade/

Appreciate it! I’m in California, and I don’t usually see less than 20 degrees where I’m at.


Sent from my iPhone using Tapatalk
Link to comment
Share on other sites

Just bypass the rad. Run an external cooler and call it good. I've done it on my old XJ and my WJ. I live where it gets cold and never had issues. My WJ has a tranny temp monitor and the other day it was ~20* here, tranny temp didnt get above 125 and it was fine. Hasnt caused issues and historically never had issues. 

Did you use the original hard lines? Because mine are so shot that they’re leaking both for the hose clamps and the disconnects.


Sent from my iPhone using Tapatalk
Link to comment
Share on other sites

6 hours ago, Dammerung said:


Did you use the original hard lines? Because mine are so shot that they’re leaking both for the hose clamps and the disconnects.


Sent from my iPhone using Tapatalk

 

Yes, I also flared the ends for new hose clamps. Would also suggest the fuel line clamps versus the worm gears. Few bucks more but a much better seal. 

Link to comment
Share on other sites

1 hour ago, Dammerung said:

On a side note because chances are I’m gonna be removing this trans cooler, radiator, and AC condenser in one fell swoop, what brand of radiator do you you guys recommend?


Sent from my iPhone using Tapatalk


Novak, Mishimoto or the old jeepspeed Griffin radiator. The Novak is the biggest core and has no trans cooler built in. Also uses an inline filler cap. Mishimoto seems to be a good all around. The new cold case radiators look promising as well

Link to comment
Share on other sites

  • 9 months later...

Reviving this thread because I’m finally getting around to it. I bough an FF Dynamics rad (which looks absolutely stunning!) and now I’m trying to decide what external trans cooler I should run. I think just running an external one without routing through to the radiator would probably be best, but what do you guys think?

Also, any recommendations on coolers? I want to know what you guys run and what fits between the condenser and grill. I’m personally looking at the Derale 13311, but I’m not too sure. Would one like that be too small?


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

Link to comment
Share on other sites

The trans “cooler” in the radiator helps warm up the tranny fluid on cold days. Since it never gets below 80 here I bypassed it and just ran a moroso stand alone tranny cooler. The tranny needs to really keep a nice steady temperature ideally in about the 160* range. The stock radiator keeps it a bit on the hot side. There are pros and cons to both and heat does kill the aw4. Keeping the radiator cooler plus an external cooler and a gauge that monitors the trans fluid temps would be great all around for most places that see all 4 seasons.

Link to comment
Share on other sites

13 hours ago, Dammerung said:

Reviving this thread because I’m finally getting around to it. I bough an FF Dynamics rad (which looks absolutely stunning!) and now I’m trying to decide what external trans cooler I should run. I think just running an external one without routing through to the radiator would probably be best, but what do you guys think?

Also, any recommendations on coolers? I want to know what you guys run and what fits between the condenser and grill. I’m personally looking at the Derale 13311, but I’m not too sure. Would one like that be too small?
 

 

I'd bypass the rad. Even in cooler weather it's never been an issue for me. Heat kills transmissions not the cold. Yes it helps get it up to temp but ideal tranny temp is 165-170 and op temp of the 4.0 is 205. 

 

As for a cooler, a stacked plate cooler IIRC provides the best cooling but is on the more expensive side. I run a standard tube and fin and it's been fine. 

Link to comment
Share on other sites

 
I'd bypass the rad. Even in cooler weather it's never been an issue for me. Heat kills transmissions not the cold. Yes it helps get it up to temp but ideal tranny temp is 165-170 and op temp of the 4.0 is 205. 
 
As for a cooler, a stacked plate cooler IIRC provides the best cooling but is on the more expensive side. I run a standard tube and fin and it's been fine. 

What tube and fin do you run?


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD
Link to comment
Share on other sites

6 hours ago, Minuit said:

Hayden 678 is a very nice piece. I have mine plumbed in after the radiator.

:yeahthat: 

 

Run it like the factory did (first through the radiator and then through an external cooler) and it will work great.   Monitor your trans fluid temps for a while to verify the cooler is working well.
 

One must keep in mind that just because your temp gauge is showing 210 does not mean that your tranny fluid is also running 210. That would only be the case if your radiator was non functional. The tranny cooler is connected to the “cool” side of the radiator where coolant temps should be well below 210 before reentering the block. The external cooler is only meant to drop the temps an extra few degrees. This was a well thought out design from the factory. If your engine cooling systems is in good working order and you use a factory style or similar external tranny cooler, the system will be in optimal operating temp range in pretty much all conditions. 
 

Link to comment
Share on other sites

49 minutes ago, Dammerung said:


What tube and fin do you run?


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

A stand alone tube and fin will overheat your tranny. You need some sort of active cooling that will work at lower speeds. The stock tranny cooler is located on the cool side of the radiator so the idea that it will see the same temps as the engine is incorrect. The radiator acts more as a thermal “regulator”. The external cooler is only needed when the tranny itself is under additional load and generating more heat than normal (towing, crawling etc). The external cooler will only help the radiator “regulator” which is a far more effective active cooling system. A stand alone tube and fin cooler will not sufficiently cool your tranny. Keep in mind that the tranny is still getting a lot of heat transferred directly from the engine since they are bolted together. Plus, being an auto tranny, generates a lot of heat on its own, heat that requires more active cooling than only using a tube and fin setup. Stable temps are the key here. And the factory knew what they are doing. Not that it can’t be upgraded, but ditching the radiator setup for only a tube and fin “cooler” is not an upgrade. 

Link to comment
Share on other sites

15 hours ago, Dammerung said:


What tube and fin do you run?


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

 

I can't remember the exact one, it is a Hayden but don't remember which one. It's fairly large.  In regards to temps. I have a temp gauge on my WJ for the tranny. With it connected to the rad it was constantly at 190+ if it was a hot day it would go 200+, once I bypassed the rad I stay around 120-190 depending on the outside temp and what I'm doing. If it's hot (90+) and I'm towing a big load or creeping up a hill it's on the higher side. For driving around town unloaded rarely gets above 170 even in stop and go. My biggest reason for bypassing the rad was the leaks, the connectors where a constant issue and I got sick of tightening them. 

 

Here's my set up

qOeaa9Gl.jpg 

Link to comment
Share on other sites

On 12/6/2020 at 1:31 PM, Smokeyyank said:

Just bypass the rad. Run an external cooler and call it good. I've done it on my old XJ and my WJ. I live where it gets cold and never had issues. My WJ has a tranny temp monitor and the other day it was ~20* here, tranny temp didnt get above 125 and it was fine. Hasnt caused issues and historically never had issues. 


 If your at 125* when -20 it would seem like 80* would put you well over 200*. 

 

Link to comment
Share on other sites

On 9/14/2021 at 10:07 PM, Dammerung said:

Reviving this thread because I’m finally getting around to it. I bough an FF Dynamics rad (which looks absolutely stunning!) and now I’m trying to decide what external trans cooler I should run. I think just running an external one without routing through to the radiator would probably be best, but what do you guys think?

Also, any recommendations on coolers? I want to know what you guys run and what fits between the condenser and grill. I’m personally looking at the Derale 13311, but I’m not too sure. Would one like that be too small?


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

 

The factory heavy duty cooling system used an external cooler in-line with the trans cooler circuit in the radiator.

Link to comment
Share on other sites

 
The factory heavy duty cooling system used an external cooler in-line with the trans cooler circuit in the radiator.

I’ve decided to run a tube and fin cooler along with the radiator cooler. Better to be safe than sorry.


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...