HOW TO: Change your front/rear diff oils

Discussion in 'How To' started by jeepkj02, May 6, 2006.

  1. jeepkj02

    jeepkj02 Full Access Member

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    Difficulty Level: 3/5

    Materials Needed:
    2.10 quarts of 75W90 or if your tow 75W140 (Rear)
    1.25 quarts of 75W140 (Front)
    1 Bottle of friction modifier (if you have a Trac-Lok)
    1 Tube of RTV or Paper gasket
    1 can of WD40
    Grease/Anti-seize
    Drain Pan
    1 can of Brake cleaner

    Tools Needed:
    Floor Jacks
    Jack Stands
    Ratchet
    Impact Wrench (optional)
    1/2" Socket
    15mm Socket
    Empty 3/8" Ratchet w/no socket
    8mm Allen
    Lower Pump Unit
    Scraper/Wire Wheel
    Hammer/Rubber Mallet
    Flathead screwdriver
    A case of your favorite beverage (beer)


    Rear axle: (about 60 minutes)
    1) Set parking brake. Jack the rear end up. Place your jack stands in place.
    2) Get your drain pan ready.
    3) Remove rubber fill plug.
    4) With a 1/2" socket, unbolt the diff cover (all 10 bolts)
    5) Take your flathead and place it between diff cover and housing and hammer, repeat on the other side.
    6) Remove cover and let the oil drain. Clean guts with brake cleaner.
    7) Inspected for any damage and wipe metallic shavings.
    8) Spray some brake cleaner on the back of the diff cover and wipe.
    9) Remove the old RTV lube on the housing and cover.
    10) Apply a small bead of red RTV on the diff cover and let it cure for between 1/2-1 hour. An alternative method is to use a paper gasket, or a LubeLocker gasket.
    11) Apply some anti-seize on the base of each bolt
    12) Begin to tighten the bolts in a star shaped pattern. Torque for the bolts are 30 ft/lbs.
    13) Start to fill the diff with oil until oil starts to come out of the fill hole. Replace rubber fill plug.
    14) Remove jack stands and floor jacks.


    Front axle: (about 45 minutes)
    1) Set parking brake. Jack the front end up. Place your jack stands in place.
    2) Remove skid plate (if applicable). There are four 15mm bolts on each corner.
    3) Get your drain pan ready.
    4) Take a 3/8" ratchet (without a socket) and remove the fill plug.
    5) With your 8mm allen remove the drain plug. Let the diff completely drain out.
    6) Replace the drain plug. Do not tighten this too much because this diff is make out of aluminum and will crack.
    7) Start to fill the diff with oil with oil until oil starts to come out of the fill hole.
    8) Replace the fill plug.
    9) Replace the skid plate. Put some anti-seize on the threads of the bolts.
     
    Last edited: Jan 28, 2008
  2. 2003KJ

    2003KJ Member

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    ahhh yes, been meaning to do a write up on this for a while now.

    The rear has been pretty much covered. The only difference is I let the RTV cure on my cover for about 30 minutes and its held up great.

    As for the front, this is really simple. There are two plugs, unlike the back. You have a drain plug, and a fill pulg. All you have to do is:

    Unblot the drain plug.
    let old oil drain out.
    Put drain plug back on.
    Unbolt fill plug.
    Fill with new oil.
    Put fill plug back on.

    YOU'RE DONE!!! This is of course, if you DO NOT have any skid plates up front. I would imagine that skids up front would have to be taken off.
     
  3. Bennett

    Bennett Active Member Administrator

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    Hey you are missing a tool... A case of your favorite beverage. (Cheers)

    Excellent write up!

    Bennett
     
  4. jeepkj02

    jeepkj02 Full Access Member

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    Forgot that one!! (beer)
     
  5. feetwet

    feetwet Full Access Member

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    Anyone tried using a suction pump to suck out the fluid and avoid taking off the diff cover?

    Any thoughts on trying this?
     
  6. tjkj2002

    tjkj2002 Full Access Member

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    Why? Feeling lazy?

    Remove the cover and get all the metal shaving out(which save bearings) and get a good look at your gears to make sure nothing is out of the ordinary.
     
  7. jggv98

    jggv98 Full Access Member

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    Wich is best or more durable, using RTV or the paper (housing cover gasket)???
     
  8. tjkj2002

    tjkj2002 Full Access Member

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    RTV,Permatex Ultra Gray RTV is the best I've found for diff covers and any other apps.
     
  9. 2002KJ

    2002KJ New Member

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    User Manual

    Just a check the User Manual:

    Correct amount of the 8-1/4 rear differential oil is 70 ounces, front is 42 ounces. The correct fill level is 1/2" below the fill hole.
     
  10. tjkj2002

    tjkj2002 Full Access Member

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    Yes but that is at idle height,not jacked up which will tilt the rear diff some making the correct fill leval at the bottom of the fill hole.
     
  11. liberty84

    liberty84 Full Access Member

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    For the rear--why do u need to place it on stands?

    Also is just one cover and one rubber plug ,right?
     
  12. Powerslave

    Powerslave Banned

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    No, they say you have to jack the rear end up, and with it up; the rear end hangs/swings down, changes the position/angle of the fill hole and diff. Not to mention, it is HARDER to fill with it on the ground, beause you can't quite get your container spout to hit the mark..

    If not jacked up, it is said you put slightly too much in, because the diff is not in the right position. I tried to top off mine (I did) by simply crawling under it. If you do not have a FULL BOTTLE of gear oil, you can't angle it up right to squirt it in, there is no room to raise the bottle up. You also have to BEND the spout end into the hole... It's doable, just more work.
     
  13. liberty84

    liberty84 Full Access Member

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    Ok so I'm gonna put the stands on the axle,
     
  14. jtp1661

    jtp1661 New Member

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    Diff Oils Service Intervals

    How often should the rear differential oil be changed?
    My Liberty is 2wd and has never been in high water or serious off-road situations.
     
  15. draganjr

    draganjr New Member

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    I wonder the samething, I know the book says every 15K miles (Schedule B) but Schedule A does not say anything about it. I know a few mechanics that say not to change it at 15K but could go longer then that exspecially if it is a normal none towing vechile. I also have a 4X2.
     
  16. TruLiberty

    TruLiberty Full Access Member

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    i read diff fluid should be every 40-60k miles.
     
  17. lynxer

    lynxer Full Access Member

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    How do I know if I need friction modifier? I have a 2002 Lib Limited.

    Thanks guys!
     
  18. Deviations

    Deviations Full Access Member

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    The easiest way to determine if you have Trac Loc is to get the build sheet from Chrysler.

    Google "chrysler build sheet" and you'll find out how (just email your vin to a specific Chrysler email)

    You'll get the build sheet back in less than a day (at least I did).
     
  19. TruLiberty

    TruLiberty Full Access Member

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    bought all my stuff today to do this tomorrow. ran me around 34 bucks, but i bought sparks too, for another 36. 70 bucks for something that would cost over 300 at a shop lol.
     
  20. lynxer

    lynxer Full Access Member

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    I got all my stuff today too!
    I am going to work on my KJ tomorrow!
    [​IMG]