4L80E possible issues.

Discussion in 'GM Powertrain' started by White Gardens, Mar 29, 2010.

  1. White Gardens

    White Gardens New Member

    Ever since I bought the truck, it made a whining noise. Originally I though it was something under the dash as it sounded electrical/mechanical, and not necessarily a high pitched whine. Today I took it to one of my local mechanics and he took it for a test drive.

    Now, the noise is a whining noise that starts when the truck starts moving. It winds up with speed. The mechanic said it wasn't coming from the dash, but the drive-train, possibly the transmission. He thought that maybe the tail bearing might be going out, or possibly the carrier bearing for the split drive-shaft. Next week I might take it back in and have him run a microphone test on the drive components so he can isolate where the noise is coming from.

    Ultimately my question is has anybody run into this type of problems before with this trans?

    Another thing I want to add to is that the trans was replaced by the previous owner about 3 months ago, and I don't know if it was a re-build or re-man.
    Last edited: Mar 29, 2010
  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    A bad transmission mount or the exhaust touching the trans or transfer case will make a noise. a carrier bearing or center bearing noise will not change pitch when the transmission shifts. A transmission gear usually changes pitch during an upshift. Rather than take it back to your"mechanic" I would suggest taking it to a transmission shop. They are more familiar with these type of noises. Oh, and A 4L80E doesn't have a "tail bearing". :)
  3. White Gardens

    White Gardens New Member

    Ya, I'll be honest and say that I wasn't quoting him with 100% confidence. He just said a bearing of some sort and I thought he mentioned the tailshaft, but he will be willing to do a diagnostic test for me no charge. I flat out told him that I do most of the work myself, and he still said he would do it for free as I bought my first truck there 5 years ago.

    The noise doesn't change in pitch at all even at shifts. It is constant with speed and starts right when you get rolling. I'm leaning towards and hoping that it's the carrier bearing; siimple fix compared to the tranny.

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