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Not enough vacum for brakes?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Nrose07, Dec 2, 2001.

  1. Nrose07

    Nrose07 1/2 ton status

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    y brake booster has always hised when I'm on the brakes. Sucking in from the interior, goin into the booster itself. but the booster/reserve will hold a vacum after I shut down the engine. So I replaced the booster with a perfect condition one out of a 9' K5, still does it but not as bad. Sometimes it's perfect, usually after some decelerating where the manifold should be greatest. So it got me thinking that I might have to much cam and not enough vacum? Would it cause these symptoms? The brakes work, alittle spongy, but the noise is annoying. And yes I have flushed and bled the brakes. Cam specs (off the top of my head) 214/216 dur. and .464/.468 lift

    Displacement, cubes, and did you say you drive a riceburner???
     
  2. Sparky

    Sparky 1/2 ton status

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    Usually not enough vacume means that the breaks will get hard not spongy. You might want to look else where for the spongy breakpart. Perhaps you have old rubber flexible break line that is expanding when you hit the breaks or your rear self adjusting breaks arent self adjusting anymore. How much vacum do you have at the maniflod? Plug in a vacum gage and get back to us. If all else fails you can get a hydraulic break booster system off a 1 ton chevy. It uses the power steering pump to power a break booster.

    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     
  3. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    A spongy pedal is usually a sign of a worn master cylinder. That may not be it, but it might be a good place to start.

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot> click here </a>
     
  4. 83K5BLZR

    83K5BLZR Registered Member

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    The sound of the booster sucking air is normal. The booster uses air from the interior to create a differential pressue within the booster itself to help provide the assisted braking. The air is sucked in through a rubber boot and passes through a filter. Make sure that the boot and filter are still present.
     
  5. Nrose07

    Nrose07 1/2 ton status

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    Filter? Where is the filter supposed to be?

    Displacement, cubes, and did you say you drive a riceburner???
     
  6. backlash

    backlash 1/2 ton status

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    In the engine compartment to the right of the booster, in-line, to the engine. It's a little plastic piece about 4 in. high if I remember corectly.
     
  7. Triaged

    Triaged 1/2 ton status

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    I think he was talking about the felt thing that is on the back side of the booster. It filters the air going from the cab to the booster and should also muffle the sound some.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
    <a target="_blank" href=http://community.webshots.com/user/triaged>See it Here </a>
     
  8. 83K5BLZR

    83K5BLZR Registered Member

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    There is usually a filter inside the dust boot of the booster. As stated in a earlier reply, it filters the air from the passenger compartment. Sorry for the delayed answer.
     
  9. ftn96

    ftn96 1/2 ton status

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    Yes, too big a cam can mess with your vacum to the brakes. But the numbers you posted off the top of your head are not large enough to really casue the problem you are tlaking about. However, if you find that the cam is the problem, you can get an electric vacum pump to remeedy the problem.

    But honey, this is the last thing I need to get for the Jimmy....?!?!?!?!?!?[​IMG]
    <a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
     

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