Chevrolet Repair: 89 GMC 1500 5.7 4x4, gmc 1500, aluminum block

Question
Hard spongy brake pedal, swishing noise in brand new master when pressing pedal NO visible leaks or fluid loss. Dash brake light flashing 9 times instead of just staying on solid. The only part of system not replaced is isolation/dump valve and the aluminum block beside it. Barrie Ontario

Answer
Hi Cory... you must still have air in the system...try bench bleeding the master. also check that the centering valve pin is not out. it's the valve that should be on the front crossmember, you may have to hold it in while pumping brakes to centre it...once it is centered then bleed brakes normally...hope this helps