Brake Booster Problem

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by RickM, Sep 5, 2017.

  1. RickM

    RickM Veteran Member

    393
    15
    Apr 16, 2004
    Gaithersburg, MD
    My pedal is way to hard. The brakes work but I have virtually no assist. With the engine running I have about 16-17 inches of vacuum at the booster.

    I disconnected the vacuum line that goes to the booster and hooked up a hand vacuum pump.

    I could not get the booster to pump up any higher than 5 inches of vacuum.

    Does this mean the booster is shot? Is there anything else that can cause the booster to not hold/pump up vacuum?

    I did remove the check valve at the booster and it is OK.

    I am using 3/8 fuel line between the test vacuum pump and the brake booster. Could the hose be collapsing internally? I heard that you should not use fuel line with the brake booster, only vacuum hose.

    Thanks
    RickM
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    9,721
    298
    Nov 4, 2004
    Ringgold, GA
    When you said you could not get higher than 5" vacuum, did the booster hold the vacuum or did it quickly leak back down? If it leaked down, the booster is bad. However, you should be able to hear a vacuum leak when the engine is idling. Another thing you might want to check if the master cylinder is pushing fluid out like it should. It's easier if you get a helper and bleed the brakes, the pedal should push easily as you're bleeding.
     

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