Master Cylinder Bleeding (In-Vehicle or Bench)
NOTE:
When the brake master cylinder has been installed new or the system has been emptied, or partially emptied, it should be primed to prevent air from entering the system.
- For in-vehicle priming, disconnect the brake lines. For bench priming, mount the brake master cylinder in a vise.
- Install short brake tubes with the ends submerged in the brake master cylinder reservoir. See Fig 1. Fill the brake master cylinder reservoir with clean DOT 3 brake fluid.
- Have an assistant pump the brake pedal, or slowly depress the primary piston until clear fluid flows from both brake tubes, without air bubbles.
- If the brake master cylinder has been primed at the bench, install it in the vehicle.
- Remove the short brake tubes, and install the brake outlet tubes.
- Bleed each brake tube at the brake master cylinder as follows:
- Have an assistant pump the brake pedal, and then hold firm pressure on the brake pedal.
- Loosen the rearmost brake tube fittings until a stream of brake fluid comes out. While the assistant maintains pressure on the brake pedal, tighten the brake tube fitting.
- Repeat this operation until clear, bubble-free fluid comes out.
- Refill the brake master cylinder reservoir as necessary. Repeat the bleeding operation at the front brake tube.