Leaking Master Cylinder- Options?

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by dadgonebroke, Jan 25, 2018.

  1. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

    Feb 26, 2004
    Bloomington, MN
    I used a new NAPA master in mine.
    I have no idea why a rebuilt would be more.

    I painted mine cast grey and shot clear over that.
    It still looks new after a few years of use.

    Make sure you do a good job of bench bleeding prior to installing.
  2. kenny77

    kenny77 Veteran Member Lifetime Gold Member

    Jul 31, 2001
    Ft. Lauderdale, FL
    I had this happen on mine. It was leaking out the rear seal and then down the front part of the booster. I spotted it real quick because the level was dropping after a couple of drives. When I took the MC off I saw there is a lip on the booster where it fits, and the fluid never went inside.
    Ending up getting a new one from NPD even had the original style bleeder valves.
    Parts stores in Florida are a joke, for my Camaro I don't bother anymore
  3. dadgonebroke

    dadgonebroke Veteran Member

    I went with the Raybestos from RockAuto with the lifetime warranty. I got it today and I'm disappointed but not surprised that it's made in China!
  4. Ote

    Ote Member

    Sep 24, 2017
    Mine was leaking where yours is. I was also getting a bit of a leak at one of the proportioning valve connections. Tightened it up and no more leaks. I bought a new Master for 60 something if I remember correctly. Leak was where it attached to the vacuum booster. Cleaned everything, bled the unit and I now have better brakes than I did 40 years ago. Power brakes even work so-so. Don't get much boost with 10 inches of vacuum.
  5. dadgonebroke

    dadgonebroke Veteran Member

    New master cylinder and the pedals still mushy! Grrr! I didn't do the install but my mechanic says he had a hard time bleeding one of the rears but got it done apparently. Looks like it's going to go back to hopefully find a solution!
  6. Ote

    Ote Member

    Sep 24, 2017
    Before I installed the new master, I purged all of the old fluid from the brake system. I read somewhere that brake fluid attracts moisture over time (40 years in my case) and water in the fluid will make brakes mushy feeling. My rear brake bleeders were rusted shut and of course wouldn't bleed. Changing out fluid might be a long shot, but could help.
  7. dadgonebroke

    dadgonebroke Veteran Member

    It's back at the shop for a gravity flush this afternoon. Knock on wood!
  8. Burd

    Burd Veteran Member Lifetime Gold Member

    Oct 6, 2011
    I sent my OG master out for a pro rebuild 17 years ago, keep it original, the front calipers out too. Cheap. It all comes back bead blasted, paint them, done.
    My mechanic suggested Dot 5 fluid too, good choice.
  9. dadgonebroke

    dadgonebroke Veteran Member

    It's back after gravity bleed and brakes better but my mechanic says barely any fluid coming out of the rear bleeder on the MC and he says it's bad. Next!
  10. Ote

    Ote Member

    Sep 24, 2017
    Maybe proportioning valve problem?

Share This Page