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NP208 Slipyoke Leak

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Innerpiece, Jan 24, 2002.

  1. Innerpiece

    Innerpiece 1/2 ton status

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    Hi all --

    My searches have yeilded nothing -- but I know this has been discussed ...

    How do you plug the NP 208 slip yoke leak (leak at the slip-yoke/driveshaft junction)??

    Thanks
     
  2. Burbinator

    Burbinator 1/2 ton status

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    Tighten the fitting or, if it's missing, JB Weld it...

    My truck did the same thing...

    Haze gray and underway...<font color=blue>or blue, in my case.</font color=blue>
    <a target="_blank" href=http://community.webshots.com/album/26246038MbQsYWKcbo>U.S.S. Nimitz II</a>
     
  3. Innerpiece

    Innerpiece 1/2 ton status

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    what fitting?? the yoke is pressed onto the splined shaft ... and It's leaking from the center of the yoke.
     
  4. Burbinator

    Burbinator 1/2 ton status

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    That's what I'm talking about; the center of the yolk. Mine had a zerk type fitting in the center that was leaking. Whether it was factory or not is beyond me...I just tightened mine up and the leak is gone. If you don't have this fitting, drop the drive shaft, clean the yolk real good and JB Weld it...I heard it works just as well; good cleaning is key.

    Haze gray and underway...<font color=blue>or blue, in my case.</font color=blue>
    <a target="_blank" href=http://community.webshots.com/album/26246038MbQsYWKcbo>U.S.S. Nimitz II</a>
     
  5. Innerpiece

    Innerpiece 1/2 ton status

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    no such fitting on mine ... just a disc like plate that "fills" the center of the yoke ..

    On a related note -- I've heard some folks talk about putting jb weld or epoxy down the inside of the slipyoke to seal it from the inside ... anyone have any thoughts on pouring a 1/4 to 1/2 ounce of molten lead down there? It should seal ... should not take away slip in the slip yoke ... and hopefully conform to the space well enough to never come loose ... would that cause a balance issue??
     
  6. Burbinator

    Burbinator 1/2 ton status

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    My truck is a '91 with a 241...perhaps that's the difference (fitting).

    Pouring some material down the inside may work, but consider the function of the slipyoke. I would think that it would break up over time (epoxy or the like). Lead may present a balance issue...I don't know. You would also have to ensure that it was super clean for an epoxy type material to adhere...I suppose it's a matter of choice on which way to go.

    Haze gray and underway...<font color=blue>or blue, in my case.</font color=blue>
    <a target="_blank" href=http://community.webshots.com/album/26246038MbQsYWKcbo>U.S.S. Nimitz II</a>
     
  7. CaptCrunch

    CaptCrunch 1/2 ton status

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    JB weld may work.... but be careful how much you use. Keep in mind it could throw the driveshaft out of balance, although I have never seen it happen in this type case. I have used a high quality gasket maker on these before and been fine in the past, but they always seem to leak again over time. The best fix is get a new yoke from the salvage yard or have yours welded up. This would especially be recomended if you flex a lot.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  8. Innerpiece

    Innerpiece 1/2 ton status

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    how would I go about welding up the yoke end? I want this issue to go away damn near forever ... I tired of dealing with silly [censored] over and over and would much rather put some $$ into upgrades as opposed to fixes
     
  9. Innerpiece

    Innerpiece 1/2 ton status

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    &gt;&gt;&gt;SPROING&lt;&lt;&lt;
     
  10. jarheadk5

    jarheadk5 1/2 ton status

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    No fitting on mine either ('87 with 208).
    I did the JB Weld-thing to my slipyoke. Works great, no noticeable vibrations beyond what's normal for my K5. As stated, cleanliness is about the most important thing to consider for this fix. You don't want the "plug" of epoxy to come loose and try to migrate in the T-case. I hung the yoke up and poured a little ATF into the tube to soak down around the bottom for a day or so (ATF has lots of detergents, so it's actually pretty good at cleaning stuff). Then I dumped the ATF and flushed it with some kerosene a few times (do this outside if possible, with a fire ext. nearby--in case you didn't know, kero is flammable[​IMG][​IMG]). I let it dry overnight, then used about half a can of brake cleaner with the little straw on it to blast any remaining crap out of the bottom. I also used an old toothbrush to help dig out any stubborn dirt. I let the yoke dry overnight in the house, to stay at room temp (wife wasn't too happy about this...) for best adhesion. Mixed up the JB Weld at the usual 1:1 ratio (maybe just a bit less hardener), and used a cut-down tongue depressor (popsicle stick would be good too, seeing as how they're basically the same) to slowly load the JB into the bottom of the tube. Work the JB into the corners, where the splines meet the "bottom" of the tube, since that seems to be where the leak originates from. Once you've got a thin, even coating in the bottom of the tube, prop or clamp the slipyoke in an upright position (tube up, yoke down) as close to vertical as you can make it. In my opinion, this step is what ensures no wacky vibes, since at room temp the JB will "flow" for a few minutes and self-level in the tube. I let it dry indoors at room temp for a few days, then popped new u-joints in and installed it. No more leak.

    Ken

    January 28, 2002--The NEW Adventure Begins...
     
  11. Innerpiece

    Innerpiece 1/2 ton status

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    a few more ??'s then -- Either you have a very long toothbrush or there is some way to get the yoke off of the splined "slip" shaft ... Everything else I get (I've tried floating sillycone down there ... It self leveled pretty well but evidently didn't last too long). How do you feel about lead? I think that would be more permanent than JB weld.
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    There is a way to remove it from the output shaft. You chock your wheels, remove your rear driveshaft, and pull out the slip yoke.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  13. jarheadk5

    jarheadk5 1/2 ton status

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    Lead would probably work if the inside of the tube was cleaned well. I have a feeling the lead wouldn't want to self-level too much after pouring unless the slipyoke assembly was heated up some, to avoid having the lead solidify too quick. But I've never poured molten lead, so I really don't know...
    As far as the toothbrush goes, I may have had to throw needle-nose ViseGrips on it for reach, but I can't recall exactly.

    Ken

    January 28, 2002--The NEW Adventure Begins...
     
  14. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    If you must try to fix it, then you should.....block the wheels, drain the fluid, unhook the speedometer, pull the driveshaft, and then undo the bolts on the tailshaft and yank it off. Then you pull your seal out and look inside for the bushing where the drive shaft rides. Take a small chizel and pound it down into the housing. Then stick a large screw driver down there and smoosh that old bushing so you tip the shaft upside and have it fall out. BE CAREFUL, don't get to over agressive and crack your housing. Drive in your new bushing and seal. Be sure to put a little RTV on the outside of the seal so it drives in easy and seals well Then you'll have to do something about the end of the driveshaft. I suppose get a brand new one if its in bad shape, or live with its in decent shape. Put things back together and use RTV to seal the tailhousing, there are no gaskets available for this.

    Its going to leak no matter what though. We've had these question asked a few times, and even once by yours truely. We found out that everyone's leaked. Mine wasn't great and I redid it all, outside of the driveshaft part, and its pretty good now, but still a little drip now and then. I changed the front too, and that has stayed dry since then. I suspect its something to do with that bushing and how they designed it. The front output doesn't have that, just the seal, and it works great. My advice would be if it isn't emptying the case out every month, then take it with a grain of salt.


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