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Weird Rattling Noise

Discussion in 'GM Powertrain' started by jdsfighter, Sep 13, 2012.

  1. jdsfighter

    jdsfighter New Member

    Hey guys, strange issue here. About 2 months ago, I had my transmission rebuilt, ever since my truck has been making this odd noise.

    It started out only happening when the engine was cold and when I accelerated hard, but now it happens when I barely press the gas accelerating from a dead stop, or when I press on it hard while on the highway attempting to accelerate at high speeds.

    The sound is comparable to taking a large jug, placing a marble inside and shaking violently. From what I can tell, the sound sounds like it is coming from the drivers side rear (closest to me).

    If I'm accelerating, and I take my foot off the pedal and press it again, generally it will stop. It also doesn't make this noise when idling or when pressing the pedal in neutral or while in park (at least not that I can tell).

    Anyone have any clue what this sound could be?
  2. jdsfighter

    jdsfighter New Member

    Update: Had my father drive it to listen, he doesn't know the sound either, but while sitting the passenger seat, it is definitely much quieter. After getting off the highway, we put it in first and listened, and it happened much more audibly. Somewhat in second, and not much at all in third. We believe it has more to do with the higher RPM rather than the gear.

    Again high RPMs don't affect it when in park or neutral. The sound seems to be coming from directly in front of the drivers seat, almost as if it were coming from directly under the dash or shortly in front of it. It doesn't seem to be coming from under the truck, as it seems almost directly in front.
  3. stratct

    stratct New Member

    Spark knock? Fill up the tank with premium gas (if you can) and run a fuel treatment like gumout or preferably lucus
  4. jdsfighter

    jdsfighter New Member

    Here's an update, replaced a gasket on the drivers side exhaust, it was insanely loose, to the point it would swing. The noise seemed to cured, but after running seafoam through the engine I thought I could faintly hear it (unlikely).

    I just did the plugs and wires which revealed a cracked distributor. But we''ll see how it runs now.
  5. jdsfighter

    jdsfighter New Member

    Further update, the engine still makes the noise (albeit more quietly), we're are beginning to think clogged cats leading too much back pressure. But it only happens under load.
  6. redNecKansas

    redNecKansas New Member

    Is your truck auto or stick, 2wd or 4wd? If auto and 4wd try to jack up the rear axle and putting it in drive and listening to the transfer case. If it is coming from there then you most likely have what is "pump rub". Mine has established this issue and I am going to start to fixing her tomorrow evening. Good luck with finding the issue.

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