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Rumbling at decelleration

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by eshorvath, Oct 17, 2002.

  1. eshorvath

    eshorvath 1/2 ton status

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    I am hearing a rumble from the exhaust when I let my foot off the peddle..
    What causes this?
     
  2. eshorvath

    eshorvath 1/2 ton status

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    Does anyone know what causes this? How can I fix it? Is it normal?
    Ed
     
  3. eshorvath

    eshorvath 1/2 ton status

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    Does anyone know what causes this? How can I fix it? Is it normal?
    Ed
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    My truck does the same thing. I'm pretty sure it has something to do with a change in the exhaust backpressure when you let off the gas........
     
  5. 90K5

    90K5 1/2 ton status

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    What gearing and tire size do you have? If its at higher speeds and you have low gears its engine braking and everything does that
     
  6. POWERMAD

    POWERMAD 1/2 ton status

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    Ya oughta hear mine LOL
     
  7. Chaz88K5

    Chaz88K5 1/2 ton status

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    did you just install a lift on it?...if so may be that the drive line angles are off...or maybe you even have a u-joint goin out..
     
  8. eshorvath

    eshorvath 1/2 ton status

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    I am running 36x12.5 tires. I think I have standard gearing, I never changed it.
     
  9. eshorvath

    eshorvath 1/2 ton status

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    I have had the lift on it for over a year. I just put a new motor in it.
     
  10. eshorvath

    eshorvath 1/2 ton status

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    What would drive line angles or a u-joint going out have to do with rumbling from the exhaust?
     
  11. eshorvath

    eshorvath 1/2 ton status

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    Would extending my ekhaust out further from the mufflers help? Right now my exhaust ends behind the mufflers. Goes from headers through 36 inch segments to mufflers.
    Has this same thing happened to you?
     
  12. Chaz88K5

    Chaz88K5 1/2 ton status

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    how about your catalitac converter?
     
  13. eshorvath

    eshorvath 1/2 ton status

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    What Cat converter???
    Mine entire EGR, smog stuff fell off when I hit a speed bump. Heehee
     
  14. Chaz88K5

    Chaz88K5 1/2 ton status

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    hum...uh....yea....i dont have a clue...next
     
  15. imiceman44

    imiceman44 1 ton status

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    definitely, if you extend pipe after the muffler, you will reduce the rumble.
    The longer you go the smoother the sound. Stock there was 3 feet after the muffler.
     
  16. eshorvath

    eshorvath 1/2 ton status

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    Is it bad to run my truck like this?
    Ed /forums/images/graemlins/confused.gif
     
  17. imiceman44

    imiceman44 1 ton status

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    Just more noise, if you don't mind it
     
  18. eshorvath

    eshorvath 1/2 ton status

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    Is it normal or ok for my truck to run like that? It only happens when I take the gas off.
    Ed /forums/images/graemlins/confused.gif
     
  19. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    i know that if you have a transmission with a lockup convertor, it will continue to stay locked up until you either apply the brake or get on the gas again. my truck does it, but it's very quiet.
     
  20. morphed86k10

    morphed86k10 1/2 ton status

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    my first thought was that its mildly backfiring. There are a lot of things that could cause it, on mine the valve which works in conjunction the smog pump was toasted (diffuser or diverter or something) so air when getting injected when it shouldn't. Do you have even a slight miss at idle? Is it worse when you are coasting at high RPM? Make sure your ignition is in good shape and timing is correct.
     

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