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Corp 10 bolt 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 -- As always thanks in advance for the info!

    I have an 87 silverado k5, TBI 305, 700 Raptor, NP 208, Corp 10 bolt, no lift, 32" tires.

    I am consistently developing leaks around the pinion. I have replaced the outer pinion bearing and seal, and the seal again. It will fix itself for a few months and come back. There aren't any other leaks in the ole pumpkin. At one point, I had an outer bearing go bad ... lots of vibration which lead to the original leak. So I have a few questions.

    (1) How much do I tighten down the pinion nut? I've heard everything from counting threads before hand to as tight as you can get it with the air gun. Would this matter in the leak?

    (2) Would a plugged vent cause this problem to reoccur? the vent line looks to be in good shape, attached to the bottom of the bed ... but I haven't actually checked it for obstructions. how would I check that?

    (3) There doesn't appear to be a worn area on the yoke that would screw up the seal. Would replacing the yoke fix things? Where do I get one? $$?

    (4) Could that original vibration in the driveline from the yoke wobbling have screwed something up so bad that it's time for an overhaul?

    Timely responses are appreciated ... I have to road trip to NOLA friday afternoon and I'd like to not frag the rear end on the way due to lack of lube.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Mine was leaking too for awhile. First couple of times the nut wouldn't stay tight, (which ruins the seal immediately apparently, wobbling) Finally I got sick of it, and replaced the yoke and seal. (third seal, first yoke swap) I tightened the nut as tight as I could with a breaker bar, after cleaning everything off, lock-tite'ing the nut, and siliconing the washer.

    Problem hasn't come back AFAIK. If it does again, or the back cover starts leaking again, I'm gonna let the thing come apart, because 5 times is too many to be under there trying to fix stupid leaks, that are not difficult (ideally) to stop.

    I too went through checking the vent. Unbolt the line from the bed, and blow into it. That was my check. I got a fair amount of air into the diff, so I figured it was clear. I did take the hose off to verify that IT wasn't obstructed first.

    The yoke I ended up with I guess (someone from here sold it to me) came off a mid/late 70's Camaro. Apparently most any 1/2 ton car/truck yoke from the 70's and 80's will work, but the 70's ones used a different u-joint, as my 12 bolt driveshaft, with the Camaro yoke, and 10 bolt axle, didn't require an adapter u-joint.

    Napa has "repair sleeves" for these, like a balancer sleeve. However, last I checked they were $30, and thats a lot of money to spend on something that is a pain to install, (and you can screw up) when you can buy a new one for $60 or so.

    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?
     
  3. Innerpiece

    Innerpiece 1/2 ton status

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    so a loosening nut causes a wobble that stretches the seal ==&gt; leak. That seems plausible and I didn't use any thread lock ..

    Anyone second that analysis?

    Should I silicone the snot out of the splined shaft?
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Can't second my own analysis, but I can say that I wouldn't silicone the splines, it could cause other problems. Clean the yoke out, where the washer sits. Then silicone both sides of the washer. That will seal the inside of the yoke up pretty well, ("outside" of yoke is sealed by the pinion seal, inside is sealed by the nut/washer) and when the nut is tightened down, the solicone will keep that side sealed as well.

    IIRC, the yoke will bottom out on the splines in a worst case scenario (crush sleeve ruined I guess) meaning that the splines probably aren't the cause of any leaks, since they don't extend past the yoke "bottom". The nut threads COULD leak, but lock tite probably helps with that. Besides, not real likely for the gear oil to leak through those threads.

    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?
     
  5. Innerpiece

    Innerpiece 1/2 ton status

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    OK last chance to object --

    Heres the plan -- Replace the seal, sillycone the thrust washer, thread lock the nut, and tighten the shite outta the nut.
    Oh yeah -- I think the nut has a nylon ring deally around the top (the one time good deal lock nut) ... since I've had it off 3 times now it prolly isn't holding anymore...


    Any objections?
     

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