How To: Change Rear Differential Fluid

Discussion in 'How-To Submissions' started by dixie_boysles, Nov 19, 2012.

  1. dixie_boysles

    dixie_boysles New Member

    Written By: dixie_boysles


    Discalimer: Neither I nor this site takes any responsibility in any damage or actions resulting from this . When performing this, you are doing so at your own risk

    In this how-to I will be showing you my method to replacing the gear oil in your rear differential. There may be other ways, but this is the way that I found best. This was for my 04' Lariat with 3.73 Limit Slip. The same steps go for a Ranger.

    Materials needed:

    - Gear Oil ( quantity and specs manual calls for)
    - 1 Tube of TransX Friction Modifier (for people with limited slip only!!!)
    - 1 tube of RTV Sealant (The gray kind if possible)
    - 1 Can of brake cleaner
    - Old Rags

    Tools Needed:

    - 3/8" Drive Ratchet
    - 1/2" Socket
    - Extension
    - 1/2" wrench if needed
    - razor blade or gasket scraper
    - Hammer
    - Oil Drain pan

    Tips:

    - Wear old cloths as you dont want gear oil or rtv sealant on you
    - I wore medical gloves to keep the smelly gear oil off my hands (that stuff stinks)
    - you should always loosen the fill plug before you start the job to make sure the plug will come out. You'll be in a tough situation if you pull the pan, drain the fluid, re-install the pan then find out you can't get the fill plug out.


    Procedure:

    Gather Materials:

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    Put truck in park and apply brake. Place Oil catch pan under rear differential

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    Using the 1/2" Ratchet or Wrench, start loosening all of the bolts

    I took them all out but the top Two, used them to hold the cover so it wouldnt fall for the next step.

    [​IMG]

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    Once that is done, it's time to break the seal. Using a combination of the screw driver and the hammer, try to pry away the bottom of the cover from the axle. dont force too much in one area.

    [​IMG]

    Then oil should start to drain

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    When it drain all the oil then go ahead and remove the remaining two top bolts. Inspect the gears

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    Use the razor blade to clean both mating surfaces on the axle and cover

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    Use brake cleaner to clean the gears and the back of the diff cover

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    Once both surfaces are clean, apply RTV sealant around all the holes and a good solid bead around the perimeter of the cover

    [​IMG]

    Put cover on and hand tighten all the bolts, let RTV dry for an hour then tighten completely using a cross bolt pattern similar to tightening lugs for wheels.

    Using the 3/8" drive ratchet, loosen oil drain plug

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    Once loose, begin filling. I mixed my friction modifier with a qrt before putting it in. fill until the oil is level with the fill hole. Plug the hole. Done.
     
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  3. djfllmn

    djfllmn ^^^ I am Mr. Clean!

    ******Before cracking the diff cover loose make sure you can get the fill plug out*****

    nice write up scott
     
  4. rango88

    rango88 Chuck Norris Drove a Ram

    Nice dude, good job :)
     
  5. Muscleford

    Muscleford Drives "the Fridge"

    I wouldn't spray brake cleaner into the diff to clean the oil off the gears it may damage seals and then you have a nice mess. Clean the cover yes.

    Just my two cents.
     
  6. OP
    dixie_boysles

    dixie_boysles New Member

    its under tips now lol. gotta read noob!
     
  7. mcdonald58

    mcdonald58 New Member

    how often should this be done? at what mileage interval? good write up.
     
  8. djfllmn

    djfllmn ^^^ I am Mr. Clean!

    depends if your submerging the diff on a regular basis or not...id say every 70-75K if you drive like i do
     
  9. mcdonald58

    mcdonald58 New Member

    I think I'll do this soon since I'm nearing 50k and I have now idea what has been done to my truck in the past.
     
  10. mcdonald58

    mcdonald58 New Member

    thanks again for this write up i will be tackling this on saturday while im doing my transmission.
     
  11. OP
    dixie_boysles

    dixie_boysles New Member

    no problem, just remember to look in your manual for how much oil you need for a Ranger, this was for my F150, but the process is still the same.

    Also, a tube or piece of hose would be of great help in filling the diff
     

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