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Brake booster...how to know if good or bad?

Discussion in 'The Garage' started by MTBLAZER89, Sep 27, 2004.

  1. MTBLAZER89

    MTBLAZER89 3/4 ton status GMOTM Winner

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    Brakes work but not good. Have to liteally stand on the pedal just to get it to slow down /forums/images/graemlins/yikes.gif Is there a way to troubleshoot this? What are the symptoms of a bad booster or a bad MC? Any ideas?

    Thanks
     
  2. Poohbair

    Poohbair 1/2 ton status

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    for the booster you should be able to start it and let it run for a few. shut it off and let it sit for a few minutes, maybe 5. Then pull the vaccum hose off the power booster. You should here a swoooooooosh of air. If not, then either the diaphram in the PB is bad, or the 1 way valve that pushes into it is bad. It has to hold pressure to work.
    As for the master cyl, cant help ya! /forums/images/graemlins/screwy.gif
     
  3. Muddytazz

    Muddytazz 1 ton status

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    If an m/c goes bad, your foot will go to the floor, so thats ruled out. If your booster is bad, it literally have to STAND on the pedal for the brakes to even think about stopping.
     
  4. ksblaze83

    ksblaze83 1/2 ton status

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    ttt....if there is fluid in the booster, does that mean the booster is bad? /forums/images/graemlins/thinking.gif
     
  5. mtnman210

    mtnman210 1/2 ton status

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    I just had the same problem. My pedal was hard as a rock and my truck didn't stop very well at all. It ended up that when the master cylinder had gone bad a few weeks before, it had leaked into the booster which caused that to go bad. I've since put in a new M/C and brand new booster and haven't any more pedal problems. plus the brakes are awesome now. So my suggestion for what you described would be a new booster.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Factory test is to start the truck, don't touch the brake pedal. Let idle for a few seconds (longer won't help) turn truck off, again without touching pedal, wait awhile (can't recall the time, 5 minutes should be enough) then try the pedal. You should have a MINIMUM of 2-3 fully assisted brake applies before the assist disappears.

    Dad had a booster go bad in his truck last year, interesting to try and stop is an understatement. Quite an expensive piece too.
     
  7. R72K5

    R72K5 Banned

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    if the booster does not hold enbough vaccum for 2 or 3 pumps of the pedal after just turnig off engine then its bad

    thgats about the only way to test a booster,

    and havngi to stand on pedal hard definitely sounds like fubar booster, for sure

    good luck
     

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