So I replaced my master cylinder on my 1995 Acura legend and there a hissing sound coming from the brake booster area. Upon more thorough inspection, I found that placing my finger on the bottom side of where the master cylinder and brake booster meet changes the pitch of the hissing, and thus the leak is coming from there. Is it enough to put gasket maker between the 2 parts to solve the issue?
Recently there was leakage detected near brake booster of my honda civic 2005 with a continously hissing sound from engine side. The problem which I was facing was that as soon as I switched OFF engine the brake pedal moved upward and became full hard and brakes failed to work. Removed brake master cylinder and found a broken round rubber seal which sits between brake master cylinder and brake booster. Replaced it and now all is fine.