Hydraulic System Bleeding

When any part of the hydraulic system has been disconnected for service, air may enter the system causing a spongy pedal action. Bleed the hydraulic system, after it has been opened, to ensure that all air is expelled.

Manual Bleeding

1. Clean all dirt from master cylinder filler cap.

2. If master cylinder is known or suspected to have air in bore, it must be bled before any of wheel cylinders or calipers. To bleed master cylinder, attach drain tube to fitting and submerge free end of tube in container partially filled with clean brake fluid. Loosen upper secondary outlet fitting approximately three-quarter turn.

3. Have assistant push brake pedal down slowly through full travel. Close outlet fitting, then return pedal slowly to full-released position. Wait five seconds, then repeat operation until air bubbles cease to appear.

4. Loosen upper primary outlet fitting approximately three-quarter turn.

5. Repeat Step 3.

6. To continue to bleed brake system, remove rubber dust cap from a rear wheel cylinder bleeder fitting.

   Place suitable box wrench on bleeder fitting and attach rubber drain tube to fitting. The end of tube should fit snugly around bleeder fitting.

7. Submerge free end of tube in container partially filled with clean brake fluid and loosen bleeder fitting approximately three-quarter turn.

8. Have assistant push brake pedal down slowly through full travel. Close bleeder fitting, then return pedal to full release position. Wait five seconds, then repeat this operation until air bubbles cease to appear at submerged end of bleeder tube.

9. When fluid is completely free of air bubbles, secure bleeder fitting and remove bleeder tube. Install rubber dust cap on bleeder fitting.

10. Repeat this process on opposite rear wheel cylinder. Then, repeat on both front calipers. Check to ensure that the caliper bleed fitting is positioned on the upper half of the front caliper. If not, the caliper is on the wrong side.

    Refill master cylinder reservoir after each wheel cylinder or caliper is bled, and install master cylinder cover and gasket. When bleeding operation is completed, fluid level should be filled to maximum fill level indicated on reservoir.

11. Always ensure disc brake pistons are returned to their normal positions by depressing brake pedal several times until normal pedal travel is established.

12. Check pedal feel. If pedal feels "spongy" repeat bleed procedure.

Pressure Bleeding

Tools Required:

• Rotunda Brake Bleeder 104-00064

For pressure bleeding, use a bladder-type bleeder tank only, such as the Rotunda Brake Bleeder 104-00064 or equivalent.

Bleed the longest lines first on the system being bled. The bleeder tank should contain enough new brake fluid to complete the bleeding operation. Use Heavy-Duty Brake Fluid C6AZ-19542-AA (ESA-M6C25-A) or DOT-3 equivalent for all brake applications. Never reuse brake fluid that has been drained from the hydraulic system. The pressure bleeder tank should be charged with approximately 69-206 kPa (10 to 30 psi) of air pressure.

 CAUTION: Never exceed 344 kPa (50 psi) pressure.

1. Clean all dirt from the master cylinder reservoir cover.

2. Remove the master cylinder reservoir cover. Fill the master cylinder reservoir with the specified brake fluid. Install the pressure bleeder adapter tool to the master cylinder, and attach the bleeder tank hose to the fitting on the adapter. Follow the instructions of the manufacturer to install the adapter.

3. If the wheel cylinders are to be bled, start with RH rear brake wheel cylinder and attach bleed tube snugly around bleeder fitting.

4. Open the valve on the bleeder tank to admit pressurized brake fluid into the master cylinder reservoir.

5. Submerge the free end of the tube in a container partially filled with clean brake fluid, and loosen the bleeder fitting.

6. When air bubbles cease to appear in the fluid at the submerged end of the bleeder tube, close the bleeder fitting. Remove the tube. Replace rubber dust cap on bleeder screw.

7. Repeat Steps 3 through 6 at rear wheel cylinder.

8. Attach a bleed tube to front brake caliper bleed screws and repeat Steps 4 through 6, starting at RH front wheel caliper and ending at LH front wheel caliper.

9. When the bleeding operation is completed, close the bleeder tank valve and remove the tank hose from the adapter fitting.

10. After disc brake service, ensure disc brake pistons are returned to their normal positions and the shoe and lining assemblies are properly seated. This is accomplished by depressing the brake pedal several times until normal pedal travel is established.

11. Remove the pressure bleeder adapter tool from master cylinder. Fill the master cylinder reservoir. Install the master cylinder cap.