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Ugh....Tranny leakin from the adapter- Steady drip.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Zeus33rd, Oct 28, 2002.

  1. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    It leaks from where the tranny and the t-case adapter meet. A fairly steady drip. Now I've got a couple questions on my options here...
    1.) Has anyone replaced the rear seal on a TH350 with it in the truck still? How difficult is it? Can I just unbolt everything and slide the t-case back far enuff to change the seal? Or does the t-case have to come out on the ground? I hope not...203's are frickin heavy. /forums/images/graemlins/crazy.gif

    2.) I've got a TH400 in great shape that I was savin to swap in when the 350 barfs its guts out. But the adapter I have is TH400 to a 208 t-case. Goin out on a limb here.....Is the TH350 to 203 adapter the same as a TH400 to 203 adapter would be? Or do I need to find a TH400 to 203 adapter? If I swap in the 400, what drive shaft mods will have to be done? Is the crossmember different? Linkage? Kick down stuff?

    Basically, I'm tryin to figure if I should just swap out the rear seal on the TH350, Or go all the way and swap the TH400.... /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/crazy.gif
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Joe, everything is different about that swap, longer transmission housing, wrong adapter, shorter rear shaft needed, longer front shaft needed, electric kickdown for TH400's, crossmember would need to be moved back. Just fix the leak and save the swap for when you have all the parts and the time to do it slowly so that you don't have any surprises.
     
  3. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Thanks Scott.....I kinda figured all that. I guess it's time to start gatherin the parts. lol, You know where there's a 400 to 203 adapter? /forums/images/graemlins/pimp1.gif
     
  4. FWP

    FWP CRS

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    Look real close, and make sure the tranny or the adapter isn't cracked, causing your leak...Just an FYI....
     
  5. thatK30guy

    thatK30guy 1 ton status Premium Member

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    What about the large O-ring? Is it still in there or did you forget to install one?
     
  6. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    I've never had the tranny and t-case seperated, the last time they were apart was probably alittle over 2 years ago when the tranny was rebuilt. Where does this O ring go? What is it called so I can go get one? Part # anyone? Looks like I'm gonna be droppin that damn heavy ass 203 this weekend....Ugh. Anyone wanna come help me? /forums/images/graemlins/crazy.gif /forums/images/graemlins/1zhelp.gif
     
  7. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    I got under there and got my nose like 2" from it...No cracks that I could see. /forums/images/graemlins/crazy.gif
     
  8. dawson444

    dawson444 1/2 ton status

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    Yea, what he said, O ring??? Where is that? Is there actually a seal there or is there suppoose to be a gasket? I just put some RTV on on the adapter where the T case meets the adapter. I actually pulled heavy thing out last week and put more RTV on there and it is still leaking. It is a TH400-203. Please help!
     
  9. CooknwithGas

    CooknwithGas 1/2 ton status

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    There is an o-ring between the adapter and the tranny. It's Round - about six inches in diameter. The t-case gets a gasket. That's the way it is on my 350 to 203. I see no reason it would be different on yours.

    One more thing - there is no other seal than the o-ring. It's easy to install as long as you have the NP203 pulled back. TAKE CARE - you know it's heavy. Mine fell when I was taking it out. Don't let yours fall and you can slide it back. Make sure you have a good jack and make a support with plywood and a few 2x4's.

    One more thing. You will have to remove the crossmember and tranny mounts - this is a small job I started that was supposed to take 20 minutes and ended up taking a few weeks because one of the tranny mount bolts broke in the t-case adapter. I ended up with a replacement t-case adapter. Use lots of penetrating fluid and don't get in a hurry taking those bolts out. - the cross member has eight bolts - two of which you have to leave in place because they are between the frame and the body. I recommend replacing the other six with new Grade 8 bolts from Lowes or Home Depot - they are cheap. I think they were less than $10 for all of the bolts, nuts, washers and lock washers.
     
  10. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Thanks for the reply. /forums/images/graemlins/smile.gif /forums/images/graemlins/thumb.gif I think what I'm gonna do is seal it up and start gatherin the parts to swap to 465/205. Then I can forget about all this $hit. /forums/images/graemlins/pimp1.gif
     
  11. thatK30guy

    thatK30guy 1 ton status Premium Member

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    What cookinwithgas said.....

    There are O-rings on ALL the adaptors, where they mate to the tranny. And like Cookin said, they are about 5 to 6 inches round and sit in a little recessed surface in the adaptor.

    I would bet you were missing this o-ring. /forums/images/graemlins/eek.gif /forums/images/graemlins/thumb.gif
     
  12. 4x4Freak

    4x4Freak 1/2 ton status

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    Any idea where these o-rings can be purchased? I just got a 205 and I need one.
     
  13. CooknwithGas

    CooknwithGas 1/2 ton status

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    In Reply to: "Thanks for the reply. I think what I'm gonna do is seal it up and start gatherin the parts to swap to 465/205. Then I can forget about all this $hit. "

    Don't expect it to be an easier job to put in a different tranny-T/C setup. You may have crossmember issues and driveshaft issues. Also shifter issues. It's always easier to clean up what you have than to put a different set-up in place. Be ready for some challenges.

    Good luck.
     
  14. thatK30guy

    thatK30guy 1 ton status Premium Member

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    You can get them from GM, but expect some hassle with them in getting the correct one. I've been back and forth with them because what their book shows is the wrong one. Their part number in the book/computer is an o-ring that is too small. They had to do some searching to get the right one. /forums/images/graemlins/tongue.gif

    To save your time and trouble with the dealer, just call someone like Randy's Ring & Pinion and they should get it right for you the first time. /forums/images/graemlins/wink.gif /forums/images/graemlins/thumb.gif
     

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