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Transfer Case Leak

Discussion in 'Early CJ5 and CJ6 Tech' started by boopiejones, Jun 29, 2020.

  1. Jun 29, 2020
    boopiejones

    boopiejones I can’t drive 55

    California east bay
    Joined:
    Mar 16, 2020
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    545
    980AECDC-0EDA-4CFB-98A5-89168AF50A41.jpeg View attachment 59288 I just replaced the fluid in my transfer case and after driving it, there is a leak out of a threaded hole in the advance adapters piece that connects the sm420 transmission to the d18 transfer case. I filled the transfer case until it seeped out the fill hole. The fluid level was much lower before I changed it, which would possibly explain why it wasn’t leaking before. Is there a special purpose for this hole that is leaking? A vent perhaps? Or should I just plug it? Assuming I should plug it, does anyone know the correct bolt size?

    Also, I replaced my transmission fluid about 3 weeks ago and I have smelled the fluid ever since while driving (but there is no leak). The shifter housing on the sm420 isn’t exactly the most air tight contraption, so I suspect I’m smelling it thru that. Is it normal to smell the fluid while driving?
     
    Last edited: Jun 29, 2020
  2. Jun 30, 2020
    Muzikp

    Muzikp Active Member

    Sacramento Ca.
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    Sep 27, 2016
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    I have the same setup, I'll go look at mine... but, is this looking front to rear on the driver side? Can't tell what I'm looking at.
     
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  3. Jun 30, 2020
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    Yes, it is looking front to rear from the driver side.

     
  4. Jun 30, 2020
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    I just figured the leak situation out. There should be two plugs, per page 3 of the instructions here: https://storage.googleapis.com/advanceadapters-com/downloads/50-2401.pdf?1593493139=1

    The advance adapters instructions were given to me by the PO when I bought the Jeep, and oddly, those instructions make no mention of any plugs. But the plugs are clearly needed and there are signs of a really old leak. My guess is that it eventually stopped leaking once the fluid level got low enough.

    The plug on the other side seems to be missing too, although I don’t see anything leaking out of it so I could be looking at the wrong hole.

    i sent an email to advance adapters to see if they know the plug size.

    any thoughts on the other question? the fluid smell from the transmission?
     
    Last edited: Jun 30, 2020
    Rick Whitson likes this.
  5. Jun 30, 2020
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    Mar 16, 2020
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    For anyone interested, I got a response from advance adapters this morning. The size for the two set screw “plugs” are 7/16"-14 x 1/2"

    Still looking for an answer on the fluid smell coming from the transmission while driving. Is that normal?
     
  6. Jun 30, 2020
    Muzikp

    Muzikp Active Member

    Sacramento Ca.
    Joined:
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    I looked at mine and I'll be dipped, I don't have the plugs either and there is a small amount of fluid that has leaked onto the case. Thanks for posting the size, guess I'll get some plugs (y)
     
  7. Jun 30, 2020
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    Let me know when you get your plugs in, and more importantly HOW you get them in. The access to the hole on the passenger side looks nearly impossible. I may need to see if my wife or 11 year old son can reach in there. Thankfully, that hole isn’t the one that’s leaking.

     
  8. Jul 1, 2020
    Ns0mniac

    Ns0mniac Member

    San Clemente, CA
    Joined:
    Aug 7, 2019
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    63
    I don't smell any fluid while driving with my 420, I don't remember whether or not the 420 has a breather though so maybe the shift tower itself is the breather and that's where your smell is coming from. My wife says I can't smell anything though. Are you sure it's not the transfer case? When mine was leaking I could smell it.
     
  9. Jul 1, 2020
    boopiejones

    boopiejones I can’t drive 55

    California east bay
    Joined:
    Mar 16, 2020
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    545
    Yes, I am sure it is the sm420 that smells. It started smelling immediately after I changed the fluid in the transmission (about 3 weeks ago). I’m 99% sure it’s just the smell of the fluid coming up thru the shift tower.

    I didn’t change the fluid in the transfer case until yesterday.
     
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  10. Jul 1, 2020
    Tom_Hartz

    Tom_Hartz Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    North Carolina
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    When I change fluids in the driveline I can smell it for awhile. My wife tells me I smell everything. No leak I would not be concerned at all.
     
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