Allison MD3060 oil leak

Discussion in 'Class A / Diesel Pushers' started by mooschi, Jan 11, 2009.

  1. mooschi

    mooschi New Member

    1997 American dream w/Allison MD3060. I have a transmission oil leak that is coming from what appears to be a pluged orifice that could be used for the dipstick if it were to be mounted on the opposite side of the transmission. The plug has a rubber seal with a metal plate above it and a 1/2 inch not protruding from the top. The oil leaks from this plug primarily when the vehicle is parked and shut off.
    Can anyone tell me how to stop the leak? Any ideas would be appreciated. :(
     
  2. dbarton291

    dbarton291 Senior Member

    RE: Allison MD3060 oil leak

    From the factory, the 3060 had the option of having the dipstick on either side of the transmission. The unused hole has a plug installed in it. The factory plug is a push in plug and I don't think Allison ever used a plug that had a nut on it(could be wrong about that but I know the new ones are a push in plug). I wonder if someone removed the factory push-in plug and replaced it with a welch type plug.

    My suggestion is, remove the plug that is in the transmission case now, probably by loosening the nut you see. Careful this plug does not fall into the trans. When the plug is removed you should just see a smooth aluminum bore. The factory push-in plug has an o-ring on it that seals the hole.

    Get an inspection mirror and a light and see if the hole in the case is damaged. If it's not, get the factory plug from an Allison dealer or distributor and replace it. You can locate your nearest Allison authorized service and parts facility by using the service locator at www.allisontransmission.com.

    If you want to try a quick and easy fix, if the welch plug that's in there is the right size, maybe you can just carefully tighten the nut.

    It leaks only when shut off because when the engine is shut off, half the oil in the torque converter drains into the sump.

    Just a free opinion. I hope this helps.
     
  3. mooschi

    mooschi New Member

    RE: Allison MD3060 oil leak

    Thanks for the response!! I will try to tighten the nut. I think I tried once before and found that the whole plug turned. Should I try holding the metal plate with a plieres and turning the nut? I will go to the Allison dealer in Phoenix and see if I can get the push in plug you mentioned. How much oil will I lose if I pull the plug out completely? I might learn something about the plug if I took it clear out.
    Thanks again for the advice.
     
  4. dbarton291

    dbarton291 Senior Member

    RE: Allison MD3060 oil leak

    I did some checking. The expander type plug was used in production until early 1997. It is part number 29514963, so you've probably got the original plug. You're looking at a bolt head. There is a nut inside the transmission. I think to really tighten that plug, you've got to drop the control module and hold the nut while turning the bolt. I was afraid I had that wrong.

    The new one piece push in plug is part number 29530328 and is used with seal part number 29507823.

    Refer the service outlet in Phoenix to Allison service information letter 11-WT-97. You may be able to pull the old plug and install the new one without dropping the control module, which is sort of a big job. That's not an oil pan you're looking at. It's an aluminum plate onto which is bolted the entire valve body, so it's heavy.

    I don't remember how much oil comes out if you pull the plug. Sounds like a good excuse to change the oil and filters and put TranSynd in it. Yes.....I'm sorta partial to TranSynd....
     
  5. mooschi

    mooschi New Member

    Re: Allison MD3060 oil leak

    Thanks again, I will be at the dealer later this week and see what parts he has in stock. Hope I can do the job without a major disassembly. Unfortunately, I just had the oil and filters changed.
     
  6. mooschi

    mooschi New Member

    RE: Allison MD3060 oil leak

    I took another good look at the expansion plug on the transmission and found it loose enough to remove without tools. I took it out and cleaned it good and found that I could tighten the bold on top by holding the metal top with a pliers. I reinstalled it and tightened it good and will watch it for a while. In the mean time I will get the new push in plug described in on of the responses so I am ready if it still leaks.

    Thanks again for the help. :)
     
  7. dbarton291

    dbarton291 Senior Member

    RE: Allison MD3060 oil leak

    No problem at all. If the expansion plug was that loose, that was probably your leak. Outstanding! Hot dang.
     

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