How Do You Bleed a Master Cylinder?

How Do You Bleed a Master Cylinder?

To bleed a master cylinder, remove it from the vehicle, and secure it in a bench vise. Attach a master cylinder bleeder kit to the output ports, push in the cylinder and pinch the lines to rid the reservoir of air bubbles.

  1. Secure the master cylinder in a bench vise

    Insert one of the mounting holes of the cylinder between the clamps on the vise. Ensure the cylinder is level before you tighten the vise.

  2. Install the bleeder kit

    Screw the fittings that come with the kit into the output ports on the side of the master cylinder. Secure the hoses of the kit to the fittings. Place the opposite ends of the hoses in a bucket.

  3. Bleed the cylinder

    Top off the brake fluid reservoir on the cylinder with fresh fluid. Push in the primary piston with a plastic or wooden dowel, and immediately pinch the hoses from the kit. Pull out the dowel, and let go of the hoses.

  4. Monitor the brake fluid level

    Monitor the level of brake fluid in the reservoir, and top off the fluid frequently.

  5. Finish the bleeding process

    Continue bleeding the cylinder until air bubbles stop rising to the top of the reservoir. Remove the hoses from the output ports, and cap the ports.