I have a 77 blazer whit power brake (rear drum,front disk) The problem is that i can't get any pressure buildup to the rear(the pedal goes to the floor)and wen i try to bleed the wheel cylinder i still get no pressure (can hold the pressure whit my finger,and whe i let go it just ooze out (no pressure!) that's whit my freind pushing on the pedal at the same time. Since i got no pressure at both wheel cylinder i tought that i had a bad line .So i removed the metal line that's comming from the front were it bolt to the rubber ones in the back ,Still no pressure (in the metal one!!) Next i removed the metal line at the combi.valve (the one that go to the rear)still no pressure at the valve!! then i remouved the line at the master and ... PRESSURE AT LAST!!!was not able to hold the pressure whit both my tumb and the pedal was harder to push(sure it was not like new but was better whit my tumb on it!!) So do i get a new master or a new metering valve or i'm way off!!! by the way i have no prob whit the front (got pressure and is bled (no more air in) ) PLZ HELP MEEEEEEE!!!!!!!!