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My 2500HD is making a weird noise...

Discussion in 'Chevy Trucks' started by Joel B., Dec 25, 2010.

  1. Joel B.

    Joel B. Senior Member
    from MN
    Messages: 233

    I have a 2002 2500HD that will intermittently make a "fssst" noise kind of like the shot of air you hear from a semi.

    Only does it when I'm moving.

    At first I thought it might be some snow hitting a hot exhaust but I tried throwing snow on the exhaust and it didn't make the same noise.

    All the gauges read fine and the truck runs good, but something is not right. I know snow stuffed in all the wrong places can cause problems………but that's not going to melt anytime soon!

  2. naturalgreen

    naturalgreen Senior Member
    Messages: 404

    where do you hear noise is it during accel or when does it happen
  3. Joel B.

    Joel B. Senior Member
    from MN
    Messages: 233

    Seems to be totally random, however, going down the highway I was hearing the noise every 12 seconds…..?
  4. mcwlandscaping

    mcwlandscaping 2000 Club Member
    Messages: 2,557

    Check all your fluids? Look under the hood for anything that doesn't look right? Smell anything out of the ordinary?
  5. naturalgreen

    naturalgreen Senior Member
    Messages: 404

    make sure no frayed belt or something wrapped up in there if its an air sound check it ist exhaust purging water through a rust hole u may only hear when water blocks hole up or down hill etc
    this is not super loud but u got me
  6. Snowzilla

    Snowzilla Senior Member
    from Iowa
    Messages: 397

    Could be a vacuum line cracked or leaking or maybe your power brake booster is going bad (has internal diaphragm that can leak). Check the vacuum line going from motor to the brake booster. If your engine bay is snow packed I would get it somewhere where it can thaw out before troubleshooting further.
  7. carkey351

    carkey351 Senior Member
    Messages: 229

    9 times out of 10 this "hissing" noise is a plugged exhaust pipe from a piece of catalytic converter that has broken and is lodged in the pipe.

    IF this is what is causing it, it usually can be heard most during acceleration, and you will usually lose some power/fuel mileage (which if you have a 6.0L will be hard to tell) FIX=replace cat or cut it out and replace with pipe (if in a non-eco state).:)

    other causes for that noise: broken exhaust manifold bolts (very common) will continue to get louder and worse over time; fuel pumps sometimes make noise when they are on their way out as well.