Brake pedal fades slowly to floor

Discussion in 'Parts Interchange' started by demo913, Jan 4, 2004.

  1. demo913

    demo913 Well-Known Member Supporting Member

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    I installed a new master cylinder, rear brakes and wheel cylinders and bled the brakes but still the pedal slowly fades to the floor.
    Any ideas?
  2. Earl Branham

    Earl Branham Certified Old Fart Supporting Member

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    demo; did you bench bleed the master cylinder? Needs to be done, or it will keep air in. Sounds like you got a bad one, though. Try the bench bleed, and if it doesn't work, take the master back and get another one.

    Earl
  3. demo913

    demo913 Well-Known Member Supporting Member

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    Yes I bled the master cylinder but it came with new bleeding instructions. This MC did not come with fittings and hoses, just two solid plugs. As the instructions said I installed it, put plugs in holes, filled MC and pumped out air. Did not seem like a good system to me but I followed the instructions.
  4. Tim Wilmoth

    Tim Wilmoth Member

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    Hey I put a master cyclinder on my car today and bench bled it like the instructions said and then bled the brakes . Works fine so I really dont know why yours is fading. Maybe as Earl said " a bad mc" Dont know:confused: Later Tim "my comet gt"
  5. Grabber75

    Grabber75 Member

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    i would start with your brakes first.......you know to start with the farthest one from the master cylinder right? just checkin.......might still have some air in them yet
  6. bmcdaniel

    bmcdaniel Senile Member Supporting Member

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    If the master cylinder has a bad bore seal the fluid will bypass it and not build pressure. Keep applying presure to the pedal. If it sinks to the floor it usually means a bad bore seal. Often you can pump the pedal back up again but steady pressure will make it sink.
  7. hotrodbob

    hotrodbob Member

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    There is an internal leak in the system. Master is the most likely source, but look at your wheels/tires. Is there any brake fluid leaking on to them? If so the wheel cylinders are the problem. Also look at your fire wall. The MC can leak out there as well.

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