FILLING AND BLEEDING THE HYDRAULIC BRAKE SYSTEM After adjusting the brake shoes always check to make sure the, master cylinder is filled to the bottom of filler opening with SAE 70Rl Heavy Duty Brake Fluid. Be sure engine is stopped, apply brakes several times to relieve the vacuum in the Hydrovac system Whenever the brake system has been disconnected the system must be bled at all four wheel cylinders, Figure 75 and the two bleed screws at the Hydrovac cylinder, Figure 74, It is recommended that a pressure type bleed tank be used for bleeding the hydraulic brake system.
Figure 75
Figure 74
To bleed the brake system proceed as follows: 1. Fill and bleed the pressure tank according to the tank manufac-
turer's instructions. 2. Connect the pressure tank to the master cylinder filler opening. 3. Loosen the upper bleed screw on the Hydrovac cylinder. When air bubbles cease to appear close bleed screw. Repeat the operation on the Hydrovac lower bleed screw. 4. Loosen the bleeder valve on the furthest wheel cylinder from the Hydrovac cylinder. Observe flow of brake fluid from the bleed screw. When air bubbles cease to appear close bleed screw. 5. Repeat this bleeding operation on the balance of the wheel cylinders.
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