Topic: Master cylinder leak

[mustang2003]

I just rebuilt my master with all new rubbers, spring , but I had to use the old piston, but it looked Ok, I keep getting a drip from the bottom of the push rod I checked and rechecked the rubber, It looks right to me, anyone have any ideas, Thanks

[Jugghead]

I have the same problem on a 350F
I rebuilt the master cylinder with a honda NOS kit, but still get brake fluid weeping from around the dust boot, coating the part of the lever that sits inside the metal of the reservoir.  Why it is doing this is beyond me, any help guys??

[paulages]

my rebuilt master was doing the same thing. when i pulled it apart, it had a small scrape in the bore, crossing the point where the center cup seals. other than a similar such defect, there isn't much that can cause such a leak. the dust boot doesn't do anything related to the brake fluid. it's the center piston cup that provides the seal at the lever end.