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2021 Diff Noise & Low Fluid

Discussion in '3rd Gen. Tacomas (2016-2023)' started by CrimSonami, Apr 16, 2025.

  1. Apr 16, 2025 at 4:51 PM
    #1
    CrimSonami

    CrimSonami [OP] Member

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    So I searched and there’s a couple threads 2 years or older that I didn’t want to resurrect. Anyway,,,,

    Bought my 2WD SR5 March 24. Heard the unusual rear end noise but contributed it to the leaf spring harmonics I’d heard about. Not it. The noise doesn’t decrease at deceleration. Been here before back in my drag racing days. Crack the fill plug on the diff and immediately get scorched oil smell. Takes almost a quart of Lucas. Jack the left wheel off the ground, lotta slack! So what kinda hassle can I expect about honoring the drivetrain warranty when I call for service?
     
  2. Apr 17, 2025 at 5:42 AM
    #2
    akimmel

    akimmel Well-Known Member

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    Is the noise constant or only a certain speed range? I'd drain all the fluid into a clean pan and see if anything concerning comes out.
     
  3. Apr 17, 2025 at 6:04 AM
    #3
    CrimSonami

    CrimSonami [OP] Member

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    It's constant. I heard it on the test drive but contributed it to the harmonics issue I'd read about since the truck only had 32k on it. Really got my attention when I ran through the Buckee's car wash, and it did the "Clang" when the green light came on and I pulled it into gear to exit. Just didn't expect this kinda issue with a Toyota product.

    I haven't drained the fluid as of yet, just topped it off. Dunno if the service dept needs to smell what I did and see if there are any metal shavings. I'm sure there is based on the slack with the tire off the ground. I've since read that some 22-23 models were recalled for this and I'm wondering if mine is a late date year model production that didn't get recognized with the potential recall. Gonna call the local dealership today and get a gage on it.
     
  4. Apr 17, 2025 at 6:18 AM
    #4
    BLtheP

    BLtheP Constantly Tinkering Member

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    What are you feeling slack in? The diff when you rotate the tire? That description doesn’t really tell anything, and if it is rotational slack, that doesn’t mean much.

    the recall is for axle shaft nuts that don’t tighten properly because of welding debris on the housing. Unlikely to have anything to do with what you were experiencing.

    The smell may or may not tell something, but all diff fluid smells quite bad and often has a burning smell anyways. I have a feeling the dealer is going to tell you it’s normal and send you out the door. Not that it’s not worth getting checked out anyways, but I wouldn’t expect a lot from your visit.
     
    t0p_d0g likes this.
  5. Apr 17, 2025 at 6:57 AM
    #5
    CrimSonami

    CrimSonami [OP] Member

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    The slack is pretty sloppy. It has a low roar on decel. And why did it accept almost an entire quart of fluid? Where did it go in 32k miles?
     
  6. Apr 17, 2025 at 7:16 AM
    #6
    t0p_d0g

    t0p_d0g 私はタコマが大好きです

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    Have you seen any sign of a leak? If not it was probably under filled from the factory. Some of these trucks have the differential howl and get it replaced to just do it again. Go ahead and take it to the dealer and at least get it documented.

    With all that said if it were my Tacoma they would replace till they got it right if it took ten differentials.
     
  7. Apr 17, 2025 at 7:17 AM
    #7
    Smacky2020

    Smacky2020 Well-Known Member

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    Unless you are definitely going through warranty, I'd do a drain to see how much sludge/material is on the magnet. If a lot, then you probably have some damage.

    Could it be a bad wheel bearing? Those usually make a decent howl when they're going.
     
    CrimSonami[OP] likes this.
  8. Apr 17, 2025 at 7:23 AM
    #8
    BLtheP

    BLtheP Constantly Tinkering Member

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    Spider gears always have slack and it always looks like a lot at the wheel. Can’t say much about how normal or bad it is without comparing it to another truck.

    Plenty of them make noise coasting or decelerating. I don’t think the deceleration part really adds anything.

    The fill spec for diff fluid is anywhere between 0-5mm below the bottom of the fill hole. Filling it up til it spills out doesn’t necessarily mean you were under full. Although you probably were under full by a little bit since you were able to get a quart in there, but even then, that just means they under filled it a bit from the factory. Doesn't mean there was a leak. There should have still been plenty of fluid to do the job it needed to do.
     

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