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Tranny sauce leaking into t-case

Discussion in 'The Garage' started by Leadfoot, May 16, 2006.

  1. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Last year I swapped in a BBC and the truck was down for a LONG time. During the BBC install I also installed a new torque converter (which I filled). When I went to fire it up a few months ago, I noticed that the truck did not move too well. I ended up adding 3-4 quarts of ATF (which should have been a sign something was wrong). I figured more leaked out than I thought, etc, etc., but last night when I went to check the gear oil in my t-case and pull the top fill plug, a large amount of red gear oil came out (well above the fill plug hole).

    Now I know this is not uncommon, but I can't remember what seals the t-case from the tranny (700r4) and t-case (NP205)? I am using AA short shaft and a figure 8 TH350/NP205 adapter. I know there is an o-ring where the adapter meets the transmission, and a gasket where the adapter meets the case but is there anything else. I know the early adapters used two seals that ride on the drivesleeve, but I'm almost positive the newer styles don't. With that said, I can't figure out what should be stopping the fluid (or if my lack of drivesleeve seals is what's causing it).

    Feeling very stupid at the moment :o
     
  2. ntaj*ep

    ntaj*ep 1/2 ton status

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    Its that o-ring, but the one it calls for is incorrect. You have to get a bunch of o-rings and find the one that seals the best. If you search this has been covered before.:D
     
  3. MEK5

    MEK5 1/2 ton status

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    Its your adapter/drive sleeve seals.
     
  4. 88Silverado

    88Silverado 1/2 ton status

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    Im too lazy to change mine, every second oil change I pull the case fill plug and drain the excess then top off the trans. I call it my automatic fluid changing setup. :doah:
     
  5. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Actually I did search :D and came up with the part number for the 0-ring .
    The problem is the o-ring seals the transmission to the adapter to stop leaks, but is not responsible for preventing transmission fluid from entering the case.

    Quote from tarussell:
    "the 350/205 versions where the adapter has an extra support bearing in it. GM did away with it after 1972."

    This is what I was thinking of. I thought GM did away with the seals that ride on the drivesleeve (which is what prevents tranny fluid from entering the t-case), but it was the support bearing that they did away with in later years. And now that I think about it, it would make no sense if they had done away with the seals :o .

    Now the question is, what is/are the part number(s) for the drivesleeve seal(s)?

    TIA.
     
  6. blaznjon

    blaznjon 1/2 ton status

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    Sorry no part numbers.Here`s what I`ve seen for seals.My 76 k5 465-205 has paper gaskets one on each side of the adapter and one seal in the adapter on the transfercase side and a snap ring in the sleeve.My old 77 k20 350-205 the two paper gaskets one on each side,and 2 seals one on each side of the adapter and a o ring in the sleeve no bearing in the adapter.the 88 k30 with 400-205 I used to have had a big oring to seal the adapter tranyside tranfercase side the paper gasket.and a input bearing retainer with a seal in it.instead of just the big snap ring holding the bearing in place on the other ones.I looked at the 465-203 in the corner of the garage,it looks like there`s only the input shaft seal on the transfercase input shaft it dosen`t look like the there`s enough space in the adapter for a seal on the trany side.Don`t you hate when you had something apart and can`t remeber what it looked like.Only thing worse is ****ty camera phone pictures that you took so that you couldn`t forget.And three of your buddys looking at the pictures and trying to guess what`s that thing over by the other blurry thing.Good Luck Jon
     

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