just hit 40,000 now brake pedal slowly goes to floor.

all the way around are disc. new brakes on front and rear are about half.

Engine not running pump and hold the pedal and it still goes to the floor. not leaking between the master cylinder and booster . so the pedal still studly goes to the floor whether the motor is running or not.

thats what I'm thinking . I have rebled the system and double check everything . whether the motor is running or not the pedal still slowly goes to the floor. this is why I bought a brand new one instead of rebuilt one to begin with .

Disconnect the M/C and plug the ports (probably with the plastic caps that it might have come with) and bleed just the M/C like that and see what it does--If you get a good pedal , then you've got a leak somewhere else. If the pedal still sinks without any fluid leaking by the plugs than you've got a bad M/C. Was the part from Advance Auto Parts? If so get your money back and get one from NAPA.

Bought it from napa , bled system one more time and got more air out. Drive it tomorrow and if peddle still Goes to floor I will plug it off and try it soley like you suggest, that is a great idea.

I hope you get it figured out. I also hope for my sake (not yours) that it is not the M/C since you already got it where I suggested.......always had the best luck with their parts. For your sake , whatever it is , I hope it's not a pain in the.................