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  1. #1

    Default Front output shaft stuck and now a squeaking noise

    My transfer case woes continue...
    (99 suburban with the NP246 AutoTrack transfer case, 1/2 ton)
    My front output shaft went through the last few months without a dust boot (had the MOST difficult time finding one). the driveshaft is now stuck on there (thanks to SMAG- snow + magnesium chloride = welded on parts). I've been spraying with PB Blaster for the last 4 days and I"m seeing some progress, but it's still not budging.

    Now it's making a squeaking noise when I drive (in forward only) that I think is coming from the front output shaft seal of the transfer case. Is it possible that the PB Blaster is causing some the seal to squeak? If so, how do I get it to stop?
    Starting to look for a lower mileage suburban now. Ever since I've hit about 175K it's been one problem after another.
    Thanks to everyone who contribute on this forum- GMTC rocks!
    Current Rides: |99 Chevy Suburban- the family truckster |93 Lincoln Town Car- 250K miles & still churning -now a fan of the Panther platform |95 BMW 325is coupe- Wheeee!
    Former GM cars: |78 Suburban 454 |71 Buick Electra 225 (deuce & a quarter) |75 Monte Carlo- 400SB- heaviest doors GM every made |70 Impala coupe- my 1st car

  2. #2


    The first thing that comes to mind is that PB Blaster is corrosive as well as lubricative (if that is a word haha)

    Google made me smart on this one.. From PB Blaster's website:

    Use caution when using PB on: plastics, paint, rubber*, fiberglass, belting and similar materials. Always apply to an inconspicuous area before proceeding with application as PB may stain such surfaces.

    *The petroleum solvents in PB will impregnate common black butyl rubber. If left in contact with these materials for extended periods of time they will begin to swell and deteriorate. However, these solvents evaporate and are not typically on applied surfaces for long periods. Components such as O-rings, control bushings, and gaskets, made from these materials get dry and hard after years of use. The penetrating/impregnating qualities of PB Blaster can restore some of the elasticity and softness to these old hardened components.
    I would assume that the rubber boot / seal on the oil seal is now starting to get soft / mushy and when you replace the shaft you will want to replace the seal.

    Inside the seal there is a metal spring that puts pressure towards the output shaft, thus creating a tight seal. if the rubber gets soft enough, it will / can wear off and you will be left with just the spring. metal on metal will squeak.

  3. #3


    Quick update:

    After spraying PB Blaster 3 different times over 1 1/2 weeks she finally broke free! The hi-temp grease that I had put on only 7-9 weeks ago was the consistency of chunky peanut butter. Cleaned it up, re-greased and installed with dust boot and we're good to go.
    Interestingly, my wife noticed that the car began to shudder and vibrate over 50 MPH during the week and 1/2 that I was letting the PB Blaster work. After re-installing the shudder is gone.
    Also the squeaking stopped and nothing is leaking from the front output shaft seal of the transfer case, so hopefully that holds and the PB Blaster didn't ruin it.

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