Transmission Cooler Modification

Discussion in 'KJ General Discussion' started by devauxr, Aug 20, 2018.

  1. devauxr

    devauxr New Member

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    So I'm having an issue as I stated in another thread concerning my transmission going into limp mode on long distance trips. This has only started happening since I added a lift kid and 31" tires. I recently replaced both speed sensors (that was a whole debacle) and replaced the fluid and filter. The Liberty will go into limp mode in the same spot on my weekend trip to my cabin which has some hills and usually involves a lot of transmssion shifting. I think I'm running into an issue with this transmssion overheating or something along those lines because if I let the jeep sit for 10 minutes there's no issue. Another confounding issue I have is that it'll throw a code, but since the journey to my cabin is so long, by the time i get home the code goes away. Another fun thing is that the jeep will not do this on the way back, as it's all downhill and highways.

    So on to the meat of the subject, I currently have the external oil cooler for the transmission which I've read on this forum is less desirable / efficient than the in radiator cooling option. My radiator seems to have the fittings for the in-radiator cooling option. I was wondering if anyone who has swapped from the external cooler to the in radiator option had some advice on fittings to make this work, or if maybe a forum thread exists on this modification. I did try the search function so I apologize if this is all covered somewhere else.
     
  2. Damotee

    Damotee Full Access Member

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    This is just a guess, but could the transmission be heating because of the larger tires? Perhaps the gearing is wrong and now causing the transmission to work harder? Just speculating, of course.
     
  3. tjkj2002

    tjkj2002 Full Access Member

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    There is a write up in the how to section I believe.Run the hot trans fluid to the radiator 1st than to the OE stand alone cooler,and then finally back to the trans for the best cooling.Don't forget to change the ATF+4 since multiple overheatings kills AFT fast.

    Yes not re-gearing leads to this issue.Seen it all the time here in Colorado where those KJ's with the 42RLE(stand alone cooler only) would get the trans over temp light on the way to alot of the trails,on the highway but sometimes going from 6000 feet top 10,000+ feet before even getting to the trail head.Those KJ's with the 45RFE(in-radiator cooler) would never have a issue.
     
  4. tommudd

    tommudd Moderator Staff Member Moderator

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    You're just trying to mask an issue with the transmission running hotter now that you have larger tires, seen it before
    I'm running 4.10s and 30.6 inch tall tires, ( more than likely same height etc as your 31s ) and runs great pulling hills even with loaded trailers etc
     
  5. devauxr

    devauxr New Member

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    I'm not trying to mask an issue, I'm trying to find a legitimate fix. I've already replaced the speed sensors and done a fluid change. I was changing the solenoid pack when I realized that my jeep had a 42RLE instead of the 45RFE and therefore the solenoid pack that I had wasn't correct. In doing research on this forum it was presented that the mod was better for cooling. While i'm fixing an issue I'd be remiss to not make the system work as well as it possibly can regardless of the issue at hand. So yes, I'm trying to find the overall issue to my transmission problem, but also I'm going to fix an inefficient cooling system. Also I must point out one thing, I don't know if the transmission is actually overheating, I know there's a light specifically for on overheating transmission, but that light never comes on, instead it's just a check engine light of which I haven't been able to get checked while it was still on. I'm just using deductive reasoning. If the overall fix is regearing I might just go back to smaller tires. This thing is a weekend cabin jeep and i'm not looking to spend the money to regear.
     
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  6. tjkj2002

    tjkj2002 Full Access Member

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    If your not going to re-gear time for smaller tires than.

    I'd stop and pull the code when the MIL comes on,not continue driving and hope for the best(IE I want to dish out big $$$ on a repair that could have been prevented).
     
  7. devauxr

    devauxr New Member

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    I've got them laying around the garage and will be swapping them back in not too long. I do want to get this thing to throw a code and be able to read it in case it's some other issue though, so maybe i'll buy a code reader or borrow one and drive it up to the cabin and pull the code on the side of the road. If there's some sort of slippage, issue with the valve body, or the solenoid pack then just swapping tires would be band-aiding the issue which i'm not too fond of.
     
  8. jeeptorino68

    jeeptorino68 Full Access Member

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    You can do the in radiator cooler with the external. Go through the radiator cooler first then the external. Maybe upgrade to a bigger external? I am using thr hayden 403 cooler with the in radiator. Good combo. Install is easy
     
  9. devauxr

    devauxr New Member

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    That sounds about in line with what I'm thinking of doing. Does anyone know which kj's actually utilized the in radiator transmission cooling? I'm just trying to make sure I get the right fittings. Or more specifically if anyone knows which fitting specifically fits the radiator that's would be super helpful. I've been doing a lot of searching for the lines and fittings but i keep running into the fittings for the external cooler.
     
  10. Akley88

    Akley88 Full Access Member

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    the 02 did. this is the part number i ordered from rock auto and it came with the cooler in the radiator. MOPAR 52080118AB
     
  11. nbas

    nbas Full Access Member

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  12. Myke

    Myke Full Access Member

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    You can get a Bluetooth obd2 scanner from Amazon for $15 and the pick up and app like Torque or Dash Command to read the codes while driving.
     
  13. nbas

    nbas Full Access Member

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