Manual Bleeding

The anti-lock brake system must be bled any time air is permitted to enter the hydraulic system, due to disconnection of brake lines or hoses for service. It is important to note that air in the hydraulic system will not cause a spongy pedal feel or additional pedal travel. However the Bosch anti-lock brake system monitors booster piston travel and booster pressure and may set a diagnostic trouble code, due to air in the brake system.

Brake lines can be bled, using a two person, manual bleeding method, as follows:
1. Depressurize the hydraulic accumulator by pumping the brake pedal a minimum of 25 times, see DEPRESSURIZING HYDRAULIC ACCUMULATOR.
WARNING: Failure to depressurize hydraulic accumulator, prior to performing this operation, may result in personal injury and/or damage to painted surfaces.

Fig. 47 - Bleeding Brake System:

2. Connect a transparent hose to the caliper bleed screw. Submerge the free end of the hose in a clear glass container, which is partially filled with clean, fresh brake fluid.
3. Slowly pump the brake pedal several times, using full strokes of the pedal and allowing approximately five seconds between pedal strokes. After two or three strokes, continue to hold pressure on the pedal, keeping it at the bottom of its travel.
4. With pressure on the pedal, have partner open the bleed screw 1/2 to 3/4 turn, close bleed screw and then release the pedal.
5. Repeat steps 3 and 4 until clear, bubble-free fluid flows from the hose.
6. Repeat the above sequence at each of the calipers. Calipers should be bled in the following order:
a. Left rear
b. Right rear
c. Left front
d. Right front