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tranny crack update

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by k5blazerus, Jan 13, 2002.

  1. k5blazerus

    k5blazerus 1/2 ton status

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    I have a 1986 chevy 4x4 3/4 ton 350 and it has a turbo 400 tranny in it. well I went to go get some stuffe out of my truck and I noticed a puddle of tranny fluid on the ground. So I was inspecting for a leak and I noticed on the bottom corner of the tailhousing that there was a hairline crack and it was leaking fluid out of it veary slow but enough to see it . is there anything I can do to fix it like have it tig weld.
    thanks colin

    Save the whales Harpoon a fat chick.<P ID="edit"><FONT class="small">Edited by k5blazerus on 01/15/02 10:32 AM.</FONT></P>
     
  2. arq

    arq 1/2 ton status

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    Re: tranny crack

    your gonna need to yank it out to do that. might as well get a new case. the 2wd/4wd versions of the cases should be the same just use your output shaft from the 4wd.

    ARQ.

    offroad baja!!!
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  3. k5blazerus

    k5blazerus 1/2 ton status

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    Re: tranny crack

    why would you need to pull it out to weld it .
    colin

    Save the whales Harpoon a fat chick.
     
  4. denver75k5

    denver75k5 1/2 ton status

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  5. arq

    arq 1/2 ton status

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    Re: tranny crack

    Depending on where the crack is, if you weld it you will heat up internal parts and if you get a seal too hot it may go bad. chances are that the crack will keep growing unless you get a real good welder to do it. paying a good welder person will cost you about the same as a case for your 400.

    ARQ.


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  6. Blue85

    Blue85 Troll Premium Member

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    Re: tranny crack

    Plus, it's an aluminum case, isn't it? To weld aluminum, it has to be very clean and aluminum is porous, so it already has ATF in it. The area would probably have to be ground away and then welded up.

    If you're screwed on this case anyway, why not try to JBWeld it and see how long it lasts?

    <font color=green>Today's Forecast: Partly cloudy with a chance of mud</font color=green>
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: tranny crack

    I agree with blue85, except I'd say what the hell, why not try to have someone run a quick bead across it? Talk to an aluminum cylinder head shop. I had one repair an AL transmission pump for me, no problems. They know what they can weld, see if they will do it. Nothing wrong with JBWeld I guess, except if its cracked from stress and is still under stress, the JB weld won't hold I'd bet.



    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
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  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: tranny crack

    To weld aluminum it needs to be clean...and I mean clean like you could eat off of literally. The amount of prep necessary for it to have a chance would require removal and dis-assembly. Also the amount of heat generated would cook any seals within 8" or so of where the weld is. Lastly, welding cast aluminum is tricky and creates even more stress in the material. On cast this is particularly bad because it is brittle. Many times welded cast aluminum will spider web from the heat stress of the welding.

    I'd get another case...and in the mean time JB weld it to try and keep the leak in check.

    Rene

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  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: tranny crack

    How clean can you get aluminum? I'm serious..I used to manufacture tables that were made out of extruded aluminum. That aluminum, no matter how we cleaned it, ALWAYS left a stain on a white rag if it was rubbed on the bare metal.

    I would guess that aluminum can be different levels of "pure" but I know that I can do the same thing on my GM auto tranny...rubbing a white cloth on the pan mounting surface will ALWAYS result in a smudge. (although that doesn't happen on a pop can, go figure)

    I understand cast (like cast iron, have to heat the metal up first) but for a crack this "simple" is it worth it to pull the t-case and then transmission, for a crack, or just weld it instead, and hope it holds?

    I see he mentioned an extension housing, if you can find one, they are very easy to replace. If its a 2wd. : (

    Dorian (who has NO experience welding ANY type of aluminum)




    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  10. chevyfumes

    chevyfumes Court jester

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    Re: tranny crack

    When my 350 cracked, I called welders and they all said the same thing about clean, and it would have been about the same for a rebuild, my question to you is do you know what caused the crack... My problem , I found was that my motor mounts went bad(I have a 74)because they had never been replaced and I'd only had the truck for alittle while , so if I were you I'd check the motor and tranny mounts really good and if you have to replace them I' d go with polyeurothane mounts its what I did... Good luck

    <font color=blue> I'd rather have a bottle in front of me, than a frontal lobotomy!
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: tranny crack

    We use all sorts of stuff to 'clean' aluminum before it gets welded. MEK, Xylene are the two most common, occasionally alcohol. The problem with cast Aluminum is that it will absorb a bit of tranny oil and the oil will try and burn when the crack is welded causing impurities in the weld. (means you get to start over again...)

    The amount of expansion and contraction during the welding process most likely will cause even more cracking depending on the rigidity of the piece and how large it is.

    Rene

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  12. k5blazerus

    k5blazerus 1/2 ton status

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    Re:update tranny crack

    well I took the t-case out and the adapter and I saw what the problem was. there is a nice little crack going around the case. how can tis happen to my daily driver. its a nice truck on 36 swampers and the last time I drove it off road was to go cyote hunting and the road was just a red cinder road . all my mounts are in good conditionI have no clue how this could have happened. I will post pictures tommorrow.
    colin

    Save the whales Harpoon a fat chick.
     
  13. denver75k5

    denver75k5 1/2 ton status

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    Re:update tranny crack

    Mine was cracked when I was Rearended by a car going about 45mph, I was told that I was missing a bar that goes from the "T" case to the engine block.

    " Wider IS Better!!!"coloradok5.com/gallery/albun51?&page=1
     

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