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NP208 rear seal leaking.. again

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bnc04, Jan 19, 2004.

  1. bnc04

    bnc04 Guest

    Hi, Stock 88 blazer with 90 thousand miles on it. I replaced the output seal on the transfer case to stop a slow leak, After 2-3 weeks, it is now back, did I do something wrong? I did replace the U joints at the same time and did not pay attention to the orientation so they may be 180 degrees out from what they were previously can this be the cause? I dont seem to have any vibration. TIA,
    Brett
     
  2. lukebaby1

    lukebaby1 1/2 ton status

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    Not all seals are created equal, The best one's I have found are the one's NAPA sells. they seem to last much longer than the local discount Auto house sells. You can even see the difference when you put the two side by side. I think the name on them is Balkamp. /forums/images/graemlins/laugh.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/thumb.gif
     
  3. 85scottsdale

    85scottsdale 1/2 ton status

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    The rubber seal around the drivehshaft on mine leaks, but doesn't drip. You can see that it leaks because it slings tranny fluid all on the under side. Haven't bothered with it though since it doesn't drip or anything.
     
  4. bnc04

    bnc04 Guest

    Thanks, This is leaking bad enough to put a bit on the driveway and slinging it all over underneath. I'll get one form NAPA and see how that goes.
     
  5. NerdBoy

    NerdBoy 1/2 ton status

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    The only time I have ever had the rear seal leak on mine was when the case filled up with fluid from a bad input shaft seal. The fluid level in the case is supposed to be low enough that it doesn't come out the rear seal. You might want to pull the fill (not drain) plug out of the case and see if fluid comes out. If it does, I'll bet you need to drop the case, and replace the input shaft seals. A good telltale sign of this is having to add fluid to the transmission without having any visible leaks.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Did you lube the seal prior to install? I'm not sure this is as critical on a slip yoke as it is on a fixed yoke, but when I did my pinion the first time, I neglected to lube the seal prior to bolting it back together, and within two weeks it was leaking again.

    After lubing the replacement, it hasn't leaked again.
     
  7. rick88blaze

    rick88blaze 1/2 ton status

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    If the bushing inside of the housing is worn out, it will let the slip yoke bounce around in the seal. This will cause it to leak also. /forums/images/graemlins/thumb.gif

    Rick
     
  8. bajaviking

    bajaviking 1/2 ton status

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    Are you sure that it is not the plug that goes into the slipyoke shaft on the u-joint end. They are known to leak and they make a real mess when they do.
     
  9. bnc04

    bnc04 Guest

    Wow, Thanks all for the advice and what to look for, I will be out of town for the next week and 1/2 but will investigate further when I return. You guys are awesome, Thanks again /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  10. Lance

    Lance 1/2 ton status

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    Make sure your output shaft on your t-case isn't bent. I had a similar problem as you described (slight vibration, fluid leak at seal).

    I replaced all the soft parts in my t-case and had my driveshafts rebuilt previous to this problem, so I was fairly certain neither of these thing were the cause of the problem. Discovered a crack in the tail-housing, thought that was the problem and replaced it, but the leak persisted. Pulled the new housing back off to clean / re-install it. While I was down there with the driveshafts removed (and wheels chocked), I had a buddy start up the truck and put the truck in drive. You could see the output shaft flexing the entire case as it made it's revolutions, which was in turn destroying the output seal.

    So if the suggestions above don't work, you may want to check into this.

    Be prepared the tranny fluid will pump out and it will make a mess. Dont' let it run like that for more than a couple of seconds to prevent burning up a bearing / pump. You should also wear some sort of eye protection as tranny fluid is NASTY.
     
  11. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    Make sure your output shaft on your t-case isn't bent. I had a similar problem as you described (slight vibration, fluid leak at seal).

    I replaced all the soft parts in my t-case and had my driveshafts rebuilt previous to this problem, so I was fairly certain neither of these thing were the cause of the problem. Discovered a crack in the tail-housing, thought that was the problem and replaced it, but the leak persisted. Pulled the new housing back off to clean / re-install it. While I was down there with the driveshafts removed (and wheels chocked), I had a buddy start up the truck and put the truck in drive. You could see the output shaft flexing the entire case as it made it's revolutions, which was in turn destroying the output seal.

    So if the suggestions above don't work, you may want to check into this.

    Be prepared the tranny fluid will pump out and it will make a mess. Dont' let it run like that for more than a couple of seconds to prevent burning up a bearing / pump. You should also wear some sort of eye protection as tranny fluid is NASTY.

    [/ QUOTE ]

    Yeah that can happen on a lifted truck that goes wheeling, the forces from a sharp angle at the yoke tend to bend the shaft.
    That is why it's better to have the fixed yoke to have the slip working in line with the shaft.
    /forums/images/graemlins/thumb.gif
     
  12. Lance

    Lance 1/2 ton status

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    [ QUOTE ]


    Yeah that can happen on a lifted truck that goes wheeling, the forces from a sharp angle at the yoke tend to bend the shaft.
    That is why it's better to have the fixed yoke to have the slip working in line with the shaft.
    /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    You're right about that. Unfortunately my wants always exceed my budget, so I had to put off installing the SYE until I could afford a new shaft from High Angle.
     

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