High Pitched Squeal from 89 Sub Rear Axle

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Big6ft6, Jan 21, 2009.

  1. Big6ft6

    Big6ft6 Rockstar 100 Posts

    I have a very high-pitched squeal that comes from somewhere near the rear axle of my truck.

    I have a 14-bolt semi-floating rear axle with 208k miles on it.

    -the noise sounds almost like needle dragging on peice of glass/smooth metal...it is that high.
    -Noise is constant, not undulating
    -the noise is not very loud, if I had a radio it would drown out noise even at low volume
    -Noise stops below 5 mph
    -Noise DOES NOT change at all (volume/pitch etc) when I step on the brakes.
    -I jacked up the rear end of the truck and put it in gear, sitting back by the axle I could hear the noise, but it is so high pitched that I could not isolate where it is coming from?
    -rear end does have fluid, I double checked.

    I just want to be sure this isn't something that I should repair now to avoid major/expensive repair later? LIke an axle bearing or pinion bearing in the differential that is going to heat up and melt something together!
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    No rocks stuck under the lip of the brake drums is there?
    Or possibly something inside the drum?
  3. Big6ft6

    Big6ft6 Rockstar 100 Posts

    Tim, that is a good idea I'll have to check. I'm scared to look at the brakes on this thing...but one of these days I should pull the wheels off and accept what might be under there. Who knows..maybe I'll luck out and the brakes will be one of the few things that were done after 150k by the previous owner!

    It seem wierd that the noise stops under 5 mph.

    another clue I'll add:
    - the noise doesn't change between acceleration or coasting.

    Can anybody help me rule out any of the following based on the symptoms, or are all these possibilities?
    -Universal joint
    -axle bearings
    -pinion bearing in the differential
    -dragging rear brake shoe (wouldn't the noise stop when I step on the brakes if this were it?)
  4. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    All the items you listed are good possibilities. I know you had it up on a lift and running, did you try using a stethescope to locate the noise?
    You can make one with a piece of flexible rubber tubing and a short section of metal tube in the end.
    I have a few disposable stethescopes they use at hospitals, if you ask the nurses they'll usually give them to you.
  5. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    a screw driver works too

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