Bench bleed the master cylinder before installation on the vehicle. Bench bleeding removes air from the master cylinder. Bench bleeding reduces the time required to bleed the brake hydraulic system after installation.

1. Plug the outlet ports.
2. Mount the brake master cylinder in a vise with the front end tilted slightly down.
3. Fill the brake master cylinder reservoir with clean brake fluid.
4. Stroke the primary piston about 25 mm (1 in) several times using a smooth round-end tool. The primary piston will not travel the full 25 mm (1 in) stroke as air bleeds from the master cylinder.
5. Reposition the brake master cylinder in the vise with the front end tilted slightly up.
6. Stroke the primary piston about 25 mm (1 in) several times again.
7. Level the master cylinder in the vise.
8. Loosen the plugs in the outlet ports one at a time.
9. Push the piston into the bore in order to force the air from the cylinder. Tighten the plugs before allowing the piston to return to its original position. This prevents air from being drawn back into the cylinder.
10. Fill the master cylinder with clean brake fluid.
11. Follow normal bleeding procedures after installing the master cylinder. Refer to Hydraulic Brake System Bleeding in Hydraulic Brakes.