Announcement

Collapse
No announcement yet.

Symptoms of bad master cylinder

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Symptoms of bad master cylinder

    Even after doing some research and reading the bently, I just want to double check what the symptoms of a bad master cylinder are. I've replaced the calipers, pads and rotors all around, and I've bled the brakes probably 4 times now with a pressure bleeder. Every time I quickly stomp on the pedal the brakes immediately grab, but every time I slowly and gradually apply the brakes the pedal goes to the floor. If I slowly press the brakes but then stomp on the pedal then the brakes instantly grab. I'm like 95% sure I've bled the brakes correctly, only pumping to about 12psi, along with working the brake pedal, and there's no leaks.
    My Feedback

    #2
    Sounds like a bad master cylinder. Pumping builds pressure but holding it down and having it slowly go to the floor means it's losing pressure when it shouldn't. Had one do this and found it was leaking inside the brake booster. It wouldn't put this off as brakes are kinda important.
    "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

    85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
    88 M3 - LACHSSILBER/SCHWARZE
    89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
    91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

    Comment


      #3
      It does sound like a master cylinder. If it's also leaking In to the booster you will need to replace that too since brake fluid will break down the diaphragm in the booster
      Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

      https://www.r3vlimited.com/board/sho...86#post4944786
      Alice the Time Capsule
      http://www.r3vlimited.com/board/showthread.php?t=360504
      87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

      Comment


        #4
        It's possible to replace a master cylinder using a pressure bleeder, right? Or do I have to do that bench bleeding procedure?
        My Feedback

        Comment


          #5
          Originally posted by E30 Wagen View Post
          It's possible to replace a master cylinder using a pressure bleeder, right? Or do I have to do that bench bleeding procedure?
          bench bleeding is recommended and should make it easier to get the system fully bled. You can do without it but why would you
          Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

          https://www.r3vlimited.com/board/sho...86#post4944786
          Alice the Time Capsule
          http://www.r3vlimited.com/board/showthread.php?t=360504
          87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

          Comment


            #6
            Figured I ought to update this thread. The issue was that I simply hadn't bled the brakes well enough. I got the help of a friend to manually bleed the system and now the pedal is nice and firm.
            My Feedback

            Comment

            Working...
            X