Brake Bleeding: Service and Repair

Bleed primary and secondary hydraulic brake systems separately, bleeding longest line first on each system. Do not allow reservoir to run dry during bleeding operation. Never reuse fluid that has been drained from hydraulic system.
1. Loosen master cylinder to hydraulic line nuts and wrap shop cloths around tubing below fitting to absorb escaping brake fluid.
2. Depress brake pedal slowly by hand to floor of cab, forcing air trapped in master cylinder out at fitting.
3. Hold pedal down and tighten fittings, then release brake pedal. Releasing brake pedal before fittings are tightened will allow air to enter the master cylinder.
4. Repeat steps 1 through 3 until air ceases to escape at fittings and brake pedal is firm.
5. Bleed rear brakes as follows:
a. Pump pedal several times, then hold pedal down firmly.
b. With pedal firmly depressed, open bleeder screw on one rear brake until pedal fades to floor, then close bleeder valve.
c. Repeat procedure until a continuous flow of brake fluid is released from bleeder valve.
d. Repeat steps 5a through 5c on other rear brake.
6. Bleed front brakes using same procedure as for rear brakes.
7. Fill master cylinder reservoirs to {1/4} inch from top of reservoirs.
8. Centralize the pressure differential control valve, if applicable, as follows:
a. Turn ignition switch to ``ACC'' or ``On'' position.
b. Push brake pedal down, allowing piston to center itself, turning off warning light.
c. Turn ignition switch to ``OFF'' position.
9. Check brake operation and ensure pedal is firm, then road test vehicle.