View Full Version : Brake pedal fades slowly to floor

2004-01-04, 21:34
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?

Earl Branham
2004-01-04, 21:52
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.


2004-01-04, 21:59
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.

Tim Wilmoth
2004-01-05, 00:52
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"

2004-01-05, 03:41
i would start with your brakes know to start with the farthest one from the master cylinder right? just checkin.......might still have some air in them yet

2004-01-05, 19:47
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.

2004-01-05, 22:23
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.