Hy DougH6100, as Sweepleader said bench bleeding the master cylinder is the best way to achieve a good bleed of the system. There is also a proper sequence in which to bleed, your truck has a Hydrovac so it is to be bled first, according to the maintenance manual the uppermost bleed screw should be bled first and then the one at the end of the tubular projection, then depending on which rear brake system your truck is equipped with, Twinplex (Bendix) or FR-3 (Wagner). Twinplex have only one bleed screw per rear wheel brake, FR-3 have two bleed screws per rear wheel brake. After the Hydrovac bleed left rear brake, if two bleed screws are present (FR-3) bleed the lower one first, then the right rear, if your truck has Twinplex rear brakes the next wheel cylinder to bleed is the one bleed screw on the left front, then the right front. If your truck has FR-3 rear brakes then bleed the right front lower then upper then left front lower then upper bleed screws. The maintenance manual says that pressure bleeding is the only method recommended for trucks larger than one ton or equipped with a Hydrovac. Hope that helps, finger tips sore now.
