I had previously posted some issues with brakes on my m813a1. Since then I have rebuilt the air pack and installed it, and installed a new master cylinder today, then I bled out the master cylinder, and air pack then the axles according to the pubs, I started and operated my truck. Previously the brakes on the front and middle axle would stick because air pressure wasnt being relieved and the fluid pressure was stuck at the brakes locking them up. Now since the install of the new master cylinder and rebuilt air pack, the truck will move and then once I press the brakes it stops, and when I let go of the brake pedal there is a time delay sometimes between ten to twenty or more seconds before the brakes release. During this ten to twenty seconds when I try to let out the clutch, the brakes will kill the motor until the air pressure makes a clicking sound and it gets built up to 120 psi on the dash pressure gauge farthest from the drivers seat, is there some sort of valve or check ball that is supposed to relieve air pressure in the system from the brake pack which would in turn release the fluid pressure from the wheels once the brake pedal is let go of? What component or part controls the air pressure relief once the brake pedal is released? I am thinking that the air pressure relief is delayed and causing the fluid pressure to keep the axles locked up. If anyone has encountered this and know how to fix this issue please , I could use some insight on this issue. Thanks in advance.