What are some signs of a transmission going bad?

Discussion in 'Questions From New Drivers' started by JohnSmith69, Aug 17, 2020.

  1. JohnSmith69

    JohnSmith69 Bobtail Member

    Feb 23, 2020
    I have a 10 speed Eaton and I've noticed it's making weird grinding noises when I let off the accelerator at 10th gear coming down to 9th and 8th. Do you think my tranny is going bad? I've replaced the clutch less than a year ago and my truck is a 2012 Freightliner with half a million miles.
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  3. Brettj3876

    Brettj3876 Road Train Member

    Nov 18, 2014
    Canceling cancel culture/CCC
    More of a winning noise or does it sound like gears. Check your ride height and carrier bearing/slop in the yoke
    JohnSmith69 and TripleSix Thank this.
  4. Ridgeline

    Ridgeline Road Train Member

    Dec 18, 2011
    Have a mechanic ride with you or have them test drive it.

    Oh and what was the last oil analysis say about the transmission oil?
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  5. TripleSix

    TripleSix God of Roads

    Apr 10, 2009
    Copied in Hell
    Mine was a whining noise in the big hole, 17th and 18th gear suddenly grenaded. Dropped to 16th gear and still made my delivery...at 50 mph max speed.
    AModelCat, JohnSmith69 and Brettj3876 Thank this.
  6. CropShop

    CropShop Bobtail Member

    Mar 24, 2020
    It could also be one of your rear ends. We had a dump truck that started growling after a rebuilt trans was installed. Called trans company and they said check your rears. Found a carrier bearing out in one.
    baha and JohnSmith69 Thank this.
  7. baha

    baha Road Train Member

    Jul 25, 2013
    1st have the ride hi. ck, replace the air ride Hi. valve and have it adj. to the factory ride Hi. look up the correct setting on the web. and have a tape with you to ck. their work
    JohnSmith69 Thanks this.
  8. MACK E-6

    MACK E-6 Moderator Staff Member

    Sep 19, 2005
    Baltimore, MD
    Last time I had a carrier bearing let go there was sort of a howl or squeal you would only hear when driving past a stand of trees on the your left, or next to to something that reflects sound like a jersey barrier. It made that noise for a good 20K miles. I tried to tell the parts changers something wasn't right because I could even feel slop in it.

    But what does a driver know? :rolleyes:
    77fib77 Thanks this.
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