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Noise while accelerating

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by gsmith, Nov 26, 2011.

  1. gsmith

    gsmith New Member

    Hello, I have a 2001 z71 extra cab and I have a strange noise while driving. The noise sounds like air sucking or maybe a loose exhaust heat shield. The noise will stop when you take your foot off the accelerator pedal and return as soon as you press the accelerator. The noise only appears while driving, not while sitting still in park or neutral. The truck is all original and i had it up on a lift and everything is tight with nothing loose or rattling that I could find, also with no codes or check engine lights. Any ideas? Thanks in advance.
  2. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    Is a a howling noise? Like a pinion bearing, u-joint, or midshaft bearing on the drive shaft? Is it 4x4? Does the noise change with hard acceleration?
  3. gsmith

    gsmith New Member

    The noise doesn't change under acceleration, it's the same sound as driving down the road with your foot on the accelerator pedal. It sounds like air passing through the air intake box maybe. I replaced the fan clutch but i just wasted my time and money still the same sound and no bearing sound. I think i have noticed that it will stop when crossing a bump in the road or my it may be just jarring my foot on the accelerator pedal. Thanks

    ---------- Post added at 10:28 AM ---------- Previous post was at 10:25 AM ----------

    I also forgot, it is a 4x4. It gets locked in 4wd only a few times a year, it hasn't been in mud or water. Thanks
  4. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    So, help me understand. It only does it in gear? If you rev it in neutral, you get no noise? Does it make the noise when you put it in gear, leave your foot on the brake and give it some gas? I was getting a "sucking" or "squirting" noise in my yukon occasionally when it shifted from first to second. I ran some injector cleaner thru and it went away. Have you opened the air box and checked in there? In cold temperatures I have seen a lot of squirrel and mice make nests in the box. I also had a weird noise with my foot on the gas in my yukon. It sounded like it was coming from the front, but it ended up being the pinion bearing in the rear, the noise just bounced under the body and made it sound like it was in the front. As soon as I let off the gas it would go away. If it only does it in gear and while moving I would have to say that it has something to do with the drive train. Either front or rear. I have been told that the front diff bearings and gear lash adjuster screw tabs tend to go bad in the trucks with the push button auto, 2wd, 4high, 4low, selector. If the tabs break off, they allow for the gear lash to change and can also make some noise. I have heard that those transfer cases are always slightly engaged in 4wd no matter what. You could always pull the front drive shaft, take it for a ride and see if that changes anything. Could be the front pinion bearing. If you have a local gear shop near you they should be willing to take it for a drive for free, the guy I went to was pointing out all sorts of sounds, if anything it will rule out front diff issues. Sorry, so long winded. I am just guessing at possible causes as I can not hear the noise.
  5. gsmith

    gsmith New Member

    Thanks Pikey, from what I can tell the drivetrain is the only option. I have held the brake and pressed the throttle at the same time and no noise. I'm guessing the drivetrain is the only thing left. Thanks for your help
  6. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    I would take it to a rear end shop. Let them drive it. Pick their brain, and then fix it yourself.
  7. gsmith

    gsmith New Member

    That was my next step. Thanks again
  8. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    Please let us know what it was when you figure it out.
  9. gsmith

    gsmith New Member

    Thanks for your help, I will be glad to let you know what I find out. Have a great Christmas
  10. JakeMatthew

    JakeMatthew New Member

    DId you ever figure out what this was? Mine has the same exact noise like you described with the bumps and everything.

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