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  1. #1

    Default Rear Differential Pinion Seal

    I recently noticed that my rear differential has started to leak oil as it is damp underneath where the driveshaft connects to the differential. I had it replaced at some shop here in Monument about a year ago. This time around I am going to replace it myself and wanted to see if anyone knows how difficult it is to replace the pinion seal and what kind of trouble i am going to run into possibly? I called the dealership and talked to the service guy who i use whenever i have something I can't do and he told me that since I have replaced the power steering gearbox and catalytic converter, etc. that this job should be pretty easy and he recommended that I just do it myself since he knows I work my suburban quite a bit. I will be replacing the differential fluid and gasket at the same time and I wasn't going to replace the pinion seal until it actually starts dripping fluid onto my driveway, think thats a safe idea? Thanks for the help.

    1996 Chevy k1500 Suburban 4x4
    5.7L 232000+ miles

  2. #2
    Sr. Mechanic John W's Avatar
    Join Date
    Sep 2007
    St Peters, Nova Scotia, Canada


    Before you replace the seal check to make sure the breather hose on the diff isn't plugged. My truck was showing the same signs of leakage but before replaceing the seal I took the hose off to check it. What I found was that the vent where it comes out of the diff was plugged with rust. I just shoved a stiff wire down through the rust into the diff housing and put the hose back on the fitting. The clean the housing off well and just watch it for a while. Oh yes, blow through the hose too to make sure that is not plugged as well.
    2000 4x4 Ext. cab 5.3 Z71
    2009 Corolla

  3. #3


    with the pinion seals you have to make sure you get the nut just tight enough to loose and it will leak to tight and you can ruin the bearing, if its just damp and not dripping i wouldnt worry about it, it it starts to drip or run down then replace it

    2003 Z71 Silverado LS
    Access roll up cover
    Bed Rails
    Billet Grill insert
    Bed Rug
    CB with PA system
    Waiting to be installed
    Two 8in RF HX2 punch( would have 12s but they got stolen)

  4. #4


    Thanks for the help. I will just keep an eye on the rear differential. I will definitely have to check the breather hose is clear as I have never thought about checking that.
    K1500 5.7L Chevy Suburban
    290000+ miles
    K&N CAI
    Black Bear Performance Tune
    TCI Servo and Shift Kit
    Long Tube Ceramic Pacesetter Headers
    Custom Side Swept Dual Exhaust
    Dual 2.5in electric DMH Performance Exhaust Cutouts
    BFG A/T 285s

  5. #5


    I might go change the differential fluid this weekend and the pinion seal hasn't developed any kind of drip. So would it be best to just leave it alone then if it hasn't developed any kind of drip? Also, last time i replaced the diff. fluid i bought a new gasket as well to install, is it possible to just take off the cover and reapply it with the seal that is on it, or would just be worth to replace the gasket while it is off anyways?

  6. #6


    i never use a gasket, i use RTV silicone gasket maker never had a leak

  7. #7


    Quote Originally Posted by Z71_guy View Post
    i never use a gasket, i use RTV silicone gasket maker never had a leak
    I never use a gasket either. RTV works just fine and as long as you start with 2 clean oil free surfaces you will never have the bolts getting loose as the gasket goes through it's hot / cold cycles.

    A note on the pinion seal. If you change it you are supposed to replace the crush sleeve, which is a PITA. The way around it is to index the nut exactly at a spot on the pinion shaft. I use a tiny wheel on a Dremell tool. Then upon reassembly use locktite on the nut and run it down to exactly the same place.

    2004 SILVERADO 2500HD LS
    Pro Comp Leveling Kit
    285-75-16 Cooper ST All Terrains
    Pro Comp Programmer
    Bilstein Shocks
    Linux Bed Liner
    Tinted Windows

    Other rides:

    1967 Landcruiser <350 Chevy>
    1970 Camaro
    1990 Geo Metro Convertible
    2007 FJ Cruiser

  8. #8


    I think i might just leave the pinion seal alone for now until it actually starts developing a drip somewhere on the pumpkin, as it sounds more complicated than I thought it was to replace the seal.

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