your original problem with the master cyl is the normal, classic failure, where the o-rings begin to allow pressure bypass, and pressure seeps away.
example - you hit the brakes and initially they are soft, but you pump them a couple of times and they firm up. also - sitting at a red light with your foot on the brake and the pressure slowly bleeds away. a couple of pumps firms them back up. also - no brake fluid is actually lost.
so - do you think this is the same thing, or are you actually losing fluid. as suggested, check capliers and cylinders for signs of leaking - black, excessive dust, or maybe even wet. maybe spray them off good with brake cleaner and recheck in a few days. i'm guess its possible for them to fail, but i've never replaced a brake booster...
also - just give them a good bleeding. that never hurts, unless you brake a bleeder.
01 1500 Reg Cab 4wd 5.2 auto 3.55 285/75/16 steps tow hooks sc3815 180 3923 trans cooler filter posilok powertrax (removed) timbren britebox pioneer head rockford amp speaker cobra cb firestick hughes plenum water pump timing chain oil pump rear main hub bearings brakes shocks cracked dash cad bushings seals ujoints trackbar tcase Robert Griffin Trans
Last edited by dhvaughan; 02-10-2010 at 10:29 PM.