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Transfer Case Leak

Discussion in 'Early CJ5 and CJ6 Tech' started by boopiejones, Jun 29, 2020 at 9:20 PM.

  1. Jun 29, 2020 at 9:20 PM
    boopiejones

    boopiejones Member

    California east bay
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    Mar 16, 2020
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    91
    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 at 11:03 PM
  2. Jun 30, 2020 at 12:13 AM
    Muzikp

    Muzikp Active Member 2020 Sponsor

    Sacramento Ca.
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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 at 12:52 AM
    boopiejones

    boopiejones Member

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

     
  4. Jun 30, 2020 at 1:05 AM
    boopiejones

    boopiejones Member

    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 at 1:21 AM
    Rick Whitson likes this.
  5. Jun 30, 2020 at 11:10 AM
    boopiejones

    boopiejones Member

    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 at 6:32 PM
    Muzikp

    Muzikp Active Member 2020 Sponsor

    Sacramento Ca.
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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 at 7:13 PM
    boopiejones

    boopiejones Member

    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 at 12:15 AM
    Ns0mniac

    Ns0mniac New Member

    San Clemente, CA
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    Aug 7, 2019
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    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 at 12:51 AM
    boopiejones

    boopiejones Member

    California east bay
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    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 at 4:54 AM
    Tom_Hartz

    Tom_Hartz Member 2020 Sponsor 2019 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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