97 suburban road noise rearend?

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Nickvto, Oct 18, 2011.

  1. Nickvto

    Nickvto New Member

    First of all this is my first suburban, and I love this truck! But I have a few issues. I bought the truck last Nov/2010. I was told the previous owner had changed the T-case with a junk yard T-case. He told me the old one would not engage. After he changed the case the truck immediately started making road noise. He told me that it was the junk yard T-case, possible bearing. I asked him if the truck was reliable with the way it sounds. He said yes, and it has been for almost a year now. I want to fix this noise though. Its annoying, and makes me feel like it might break down with a heavy load or long haul...like say 4 hours straight freeway. I took it to a shop right after I bought it. They told me it was the rear-end. So I'm not sure who to believe.

    The noise:
    It starts almost from a roll and builds as you go through the gears. at about 60 it gets a little softer but not much, and will drive you crazy after awhile. It will however get quite if you take your foot off the gas, and I noticed spinning the tires in the snow I could replicate the sound without going to far. I also noticed when the truck bounces the noise gets better on the up, and worse on the down.

    Now I had some issues with the 4x4 mid winter. It stopped engaging into 4x4 high. I think I had the blinking light of death on the switch. Anyways after a few try's the light went solid but did not engage. It will however go into 4 low with a clunk. Maybe it's this thermal actuator switch I have read about because it stopped working in the very dead of winter.

    Any help would be appreciated. I can add any information you think might make a difference. Please...If you have had any of these issues please inform me. I have an 18 month old, and cannot drive this beast much longer knowing it has a big fail coming soon. I just might have to upgrade to an 01-04 suburban:)
  2. TMair

    TMair Member

    I think the first thing I would do is either get a second opinion, from another shop, I would explain to them what you have been told by the guy you bought it from and see what they say, second option would be to get it up on blocks or what ever, with the rear tires free to spin, put it in gear and get under it so you can listen for where the noise is coming from, if you have to use a screw driver, or long metal bar, you can put that against the T case, and listen through it by putting the other end next to your ear, then just check around, the noise can telescope through the frame, and the body making sound like it is coming from where it is not if you just try to listen to it as you drive it.
    Did the first shop you took it to just drive it down the road, or did they put it up on a hoist so they could get under it?

    Edited to add: If you do put it up on blocks make sure it is secure, I would hate to have you inadvertanly run over yourself. Also make sure you have nothing on that can get caught on the drive shaft, or other moving parts!!!!!
    Last edited: Oct 18, 2011
  3. Nickvto

    Nickvto New Member

    97 suburban road noise

    Thank you for the response. I was thinking about taking it to a dealer. I thought maybe with there experiance with suburbans that an older tech would know whats wrong with it.

    I have put the truck on jacks, and I can hear the noise but, I have no clue where its coming from. And like the 1st shop said they wouldnt know it was truly the rearend untill they opened it up.

    The guy I bought the truck from said it was prob a bad bearing on the input shaft of the T-Case. I do know that the truck has a slight clunk on start up, and when putting it in gear. Now I know this could be u-joints, but I tried to move the shaft and could not budge it. It does have some in/out play.

    Is it possible, that with a bad bearing on an input/output shaft act as a U-joint clunk? And could that explain why the noise goes away slightly when the truck is bouncing, flexing the drive shaft as the rearend goes up and down. I say bouncing becuase the previous owner installed adjustable air shocks in the back for hauling. Is this something that came stock? There are no markings on the shocks and I have no clue what there max psi would be. Of course with less psi it bounces like car with bad shocks. I have 45psi in it now, and have read that some air shocks go to 200psi. The more psi the better the truck rides. Im just afraid of blowing the shocks not knowing how much psi they can handle. It drives great under load (pulling 16ft trailer).

    If these air shocks are not oem, then allowing the truck to bounce like that, I would think it could have some impact on the bearings, shafts and U-joints. May have answered my own question but I value other opinions.

    Thanks for you time.

    P.s. Im not sure how the first shop checked it out
    Last edited: Oct 19, 2011
  4. TMair

    TMair Member

    A bad bearing can allow the shaft to drop, or move in/out, which could cause a clunk sound, especialy in the transmission/transfer case, if you take a long bar, or a long screwdriver and put one end on the transfer case where the shaft goes in, and where the out put shaft comes out, and put the other end next to your ear you can hear what is going on in there, it will help you to narrow down where the noise is coming from, if a bearing is bad you should be able to hear it doing the bar method, or you could go to the parts store and get a stethoscope made to listen for those things, they look just like what the Dr. uses, except it will have a long slender rod on the end that you put on what ever you want to listen to.
    Before I paid a lot of money to have some one tear it down I would try and make sure what needs torn down and this is a way to narrow it down.

    Edited to add: Sorry I can't help with the shocks, I would think if you google the brand and ask about pressure you could find that info.

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