brake problem

[ryanruggles at uniserve.com (Ryan Ruggles)]

I just put in a used brake master cylinder into my rabbit Gti.  I bled the system.  It seems to brkae normally at first but If I keep my foot on the peddle for more then a few seconds the peddle goes down further like it loses pressure.  Could I still have air in the lines?  I didn't "bench bleed" it and I don't exactly know what bench bleed means.  Any ideas?


Ryan