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Rear differential hissing

Discussion in '2nd Gen. Tacomas (2005-2015)' started by toglide, Jul 12, 2011.

  1. Jul 12, 2011 at 1:27 PM
    #1
    toglide

    toglide [OP] Member

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    Okay this was really weird. I'm not sure if anyone else has had this happen to them,
    so I thought I would post it and find out.

    I was in the process of changing my rear differential oil and removing the fill plug. After breaking the plug loose and turning it to remove it, it started hissing like there was pressure or a vacuum inside the differential. I have never seen this happened before but admit I haven't change differential oil that often. I did check the vent after draining the oil and it looks fine. Just wondering if this is normal?
     
  2. Jul 12, 2011 at 1:34 PM
    #2
    Crom

    Crom Outside...

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    Entirely possible. If the air trapped in the diff became hot it would expand creating pressure, and you relieved the pressure when you open the fill plug. That said, the air should not be trapped in the diff.

    In the photo below, the stem sticking out of the axle housing is supposed to allow the diff to breathe. You can see where mine spit up some diff oil, probably when off roading on bumpy roads in the desert.

    Maybe yours got plugged up? :notsure:

    [​IMG]
     
  3. Jul 12, 2011 at 1:36 PM
    #3
    jberry813

    jberry813 The Mad Scientist

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    ^This.

    You're diff breather is clogged.
    Time for diff breather mod.
     
  4. Jul 12, 2011 at 6:17 PM
    #4
    joes06tacoma

    joes06tacoma Well-Known Member

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    Yep, wait too long and it might take out an axle seal too.
     
  5. Jul 12, 2011 at 8:19 PM
    #5
    toglide

    toglide [OP] Member

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    Thanks guys I'm going to pull that breather out tomorrow and have a closer look at it.:bowdown:
     
  6. Jul 12, 2011 at 8:25 PM
    #6
    jberry813

    jberry813 The Mad Scientist

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    ...too much shit to list.
    When I did my diff breather mod, my old breather had turned into a one-way check valve. It could release built up pressure inside the diff (blowing) but could not suck in air once the diff cooled down.
     
  7. Jul 13, 2011 at 10:14 AM
    #7
    toglide

    toglide [OP] Member

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    So I pulled the breather out today and the same thing happened. The rear different is under a vacuum.
    So I pulled the cap off the breather and found this.

    [​IMG]


    It's a check valve.
     
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