Brake question-'92 GMC PU

Discussion in 'Shop Talk' started by Old Jack, Nov 6, 2005.

  1. Old Jack

    Old Jack Truth Seeker

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    My brakes are gasping when I hit them. Sounds like it's sucking air. I checked the master cyl and the wheel cyls and don't see any leaks. It appears to have a vacuum assist coming off the intake manifold.
    The hose looks good, I can't see any breaks or wear.
    The brakes work good , I'm just concerned about this sound.
    It's a 92 GMC 1/2 ton sierra
    Any ideas?
     
  2. Beeman

    Beeman Well-Known Member

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    The power brake booster uses vacum for the assist. Is the power assist working properly? A quick test is to pump the brakes a few times with the truck off. While holding your foot on the brake pedal start the truck, the pedal should drop as vacum replenishes to the booster. In line at the booster should be a vacum check valve which holds vacum at the booster. After running the truck shut the truck and pull that check valve out of the grommet at the booster, you should hear the air flow into the booster as you open the vacum.
    I've heard many of them whoosh, as long as it's working I wouldn't worry. The only fix is replacement of the booster.
     

  3. Old Jack

    Old Jack Truth Seeker

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    Thanks Beeman.
    I tried the tests. Everything went as you explained.
    Does mean that down the road I should expect to replace the booster?
     
  4. idontno

    idontno Well-Known Member

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