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Brake Problem

Discussion in 'General Chevy & GM Tech Questions' started by dwcruz, Mar 16, 2009.

  1. dwcruz

    dwcruz New Member

    I have a 89 fullsize Blazer Straight axle front and rear. With brake booster and regular master cylinder. No hydro boost. The problem I am having is after I gravity bled and had someone pump the pedal as I open the bleeder screw, I have no air bubbles coming out of the wheel cylinders or calipers. Just clean fluid, the pedal feels solid until I start the truck and step on the brake pedal then it goes almost to the floor. I can pump the pedal a few times and build pressure but then as you hold the pedal down it slowly goes back down. If I turn the truck off it feels like it has a solid pedal again. Any help would be appreciated???
    Dan
  2. mjalstad

    mjalstad New Member

    Maybe try bleeding it at the master cylinder as well. otherwise you may want to search and see if you can find if it has a specific bleeding sequence and try that.
  3. dwill3015

    dwill3015 New Member ROTM Winner 1000 Posts

    Welcome to the site!
  4. Z71_guy

    Z71_guy New Member 1000 Posts

    welcome to the site
    try to find the bleeding sequence and try it like that
  5. ct9a

    ct9a New Member 1000 Posts

    Welcome to the site. Try bench bleeding the master cylinder first. If the pedal continues to go to the floor after that, then I would start looking for a leak somewhere. Check your pedal push rod, sometimes the seal in the MC goes bad and can start to leak down the rod and into the cab. Good luck.
  6. GaryL

    GaryL New Member ROTM Winner Platinum Contributor 1000 Posts

    When you are bleeding the system, the truck must be level. If not level, air can get trapped in the high part of the wheel cylinders/calipers. Other than that, it sounds like you may have a leak at one of the wheels.

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