Bleeding the Brake

Discussion in '80-Series Tech' started by hkimsoft, Jul 15, 2005.

  1. hkimsoft

    hkimsoft

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    Should brake be bleeded with engine running? Some say yes, some say no...

    Thanks all.
     
  2. flintknapper

    flintknapper

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    Its not necessary to use the brake power booster to bleed the brakes, and IMO it takes away "the feel" of the pedal. Without the power booster you can pump up the pedal and hold it with a better sense of feel for leak down and the overall effort required.

    Just my thoughts.
     
  3. hkimsoft

    hkimsoft

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    Thanks. I just did bleeding because of soft/spongy feeling when depressing the brake pedal. But soft/spongy feeling is still there... No leaks, Brakes just fine, No sinking... I guess I would have to try replacing the MC. Any other thoughts?
     
  4. santiagol

    santiagol

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    Proportioning valve

    Make sure you also bleed the proportioning valve in the back.
     
  5. flintknapper

    flintknapper

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    What you describe is usually air somewhere in the system. I always bleed the MC first and then the lines. Also...check the condition of your flex lines for swelling (look for bulges or soft lines) this can cause what you describe as well.
     
  6. sixsracing

    sixsracing

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    Before you condemn the M/C you need to hold pressure on the pedal and see if it "leaks" down to the floor. If it doesn't, then the M/C may be fine. How long has it been since you checked the rear pads. Worn rear pads can give you a spongy feel in the pedal.
     
  7. santiagol

    santiagol

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    Besides air in the lines, also check the condition of the brake fluid - it has great affinity for water/humidity, which will ruin the compressibility properties of the brake fluid. If the brake fluid is cloudy or dirty, flush the whole thing until it is clean. It is easy and inexpensive, all you need is a willing partner to pump the brakes and keep the system full while you crawl around on your back.
     
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