another bleeding the breaks question

rustynut Posted By rustynut, Sep 15, 2009 at 4:14 PM

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  1. rustynut

    rustynut
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    Jan 5, 2008
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    hi all,
    got a gmc 2500 4wd
    changed the steering pump and cooler a short while ago
    to my surprise this pump is not only for steering but for the power breaks as well
    anyone know if i need to bleed those breaks after this type of surgery ?
    rn
     
  2. Flatbedford

    Flatbedford
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    Mar 17, 2009
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    First. Do the brakes work OK? If they do, don't mess with them.
    I'd say you should not have to bleed. The power assist and the actual brake system are separate systems. Your truck must have what is called "hydro boost brakes ". You only need to bleed the system if you open the brake lines, wheel cylinders, or calipers.
    I didn't know that GM trucks used this setup. Is your truck diesel powered?
     
  3. WayneB

    WayneB
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    Aug 7, 2009
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    Flatbedford is correct, hydro-boost and brake hydraulics are separated. As a side note, pulling a vacuum on the power steering reservoir while running will get rid of the whining quickly. They have a hose and a suction cup type adapter that they sell at some parts stores and from some tool dealers that FINALLY became a required tool some five yrs or so ago at the dealerships, boy did that make a PITA job faster and better. Nothing worse than trying to get the foam from forming then running the wheels back and forth twenty five or more times.
     
  4. Dune

    Dune
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    I had hydroboost brakes on a C-30, 6 wheeler.
     
  5. fbelec

    fbelec
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    hydro boost is a real piece of work. try cornering with a heavy load on the back then while turning the wheel as far as it will go to make the corner you put on your brakes and the wheel and the brakes have a war with each other.
     
  6. Flatbedford

    Flatbedford
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    Mar 17, 2009
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    That's why I'm curious. I wouldn't expect to see hydroboost on a 3/4 ton. I'm thinking diesel because diesels don't make enough vacuum for power brakes. I know that the Ford light truck diesels have, or maybe had (don't know about the newer ones) a vacuum pump for the power brakes.
     
  7. struggle

    struggle
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    6.5 Turbo diesel? I had one in 1994. Same system with hydro boost brakes.
     
  8. rustynut

    rustynut
    Feeling the Heat 2.
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    Jan 5, 2008
    364
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    Loc:
    mid mich
    just wanting to be sure on that bleed or not
    brakes seem a bit light
    when the cooler went out i lost brakes and steering at the same time - totally
    was messing around in the yard so no problem with traffic.......
    never saw that one before
    thats a 3/4 ton gmc 4wd w/ 6L gas motor
    thanks for the tip on the whining
    it seems to have finally stopped
    rn
     
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