Allison MT 643R

Discussion in 'General RVing' started by opus, Oct 4, 2010.

  1. opus

    opus New Member

    Temperature sending unit issue. Is this what you would call a "sump type" sending unit?

     http://lh4.ggpht.com/_4XnTo50N_sc/TKZvAjszTyI/AAAAAAAAAt4/6OfN0nB08d8/s800/1001001727.jpg

    If so, obviously the sending unit is gone. Can I unscrew this plug and get a replacement without taking an oil bath? Is that a dry hole beneath that big plug? 
     
  2. dbarton291

    dbarton291 Senior Member

    Re: Allison MT 643R

    The oil pan on the MT643 (later production), had the dipstick opening on one side (plugged with a plastic plug at the factory, the OEM put in the dipstick tube) and that brass plug on the other side. That hole goes directly into the pan. If you take the plug out, oil will come out of it.

    Whatever kind of sender that is that's been installed into that brass plug is definitely not factory. It's probably broken off inside the plug. That's why it's not leaking.
     
  3. opus

    opus New Member

    Re: Allison MT 643R

    Come to find out, I guess it is a factory install. I talked to the gauge manufacturer and they are going to send me the correct sending unit.
     
  4. dbarton291

    dbarton291 Senior Member

    Re: Allison MT 643R

    Maybe somebody's factory, but not at Allison.
    The trans isn't original, either. The R in MT643R stands for ReTran.
     
  5. opus

    opus New Member

    Re: Allison MT 643R

    My mistake then, I was told the R stood for retarder.
     
  6. dbarton291

    dbarton291 Senior Member

    Re: Allison MT 643R

    If it has an output retarder, these were called the MTB643.

    The world transmissions have designations like MD3060R for retarder.
     
  7. opus

    opus New Member

    Re: Allison MT 643R

    Ok, thanks for clarifying this for me. I found the manufacture and the part number for the gauge/sending unit. Now, to find one. :)
     

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