How to Bench Bleed Your Brake Master Cylinder

  • 1-3 hours
  • Intermediate
  • 6-50
What You'll Need
Work table or bench
Fresh brake fluid
Strong and firm plastic rod
Protective overalls and working gloves
Plastic tubing

It is mandatory to bleed brakes after installing a new brake master cylinder. The procedure makes sure that air is removed from the unit. It might take some time before desired results are achieved; therefore exercise patience when pumping through and through. However, to make the bleeding process more effective, use bench bleeding technique. This is where the master cylinder is supported on a work bench as the procedure as carried out.

Step 1 – Remove Brake Fluid

Use a large syringe to remove any brake fluid from the brake fluid reservoir. Attach plastic tubing and drain it into an empty bucket. Take care not to spill the fluid on other parts of the car as it easily destroys paint. Keep it far away from eyes as well; it is good practice to wear eye goggles when handling brake fluid.

Step 2 – Disconnect Rubber Brakes Lines

Place a drip pan on the floor before disconnecting brake lines from the metal lines in the car. Excess fluid can drain into the pan to minimize spillages. Carefully remove the reservoir from the car with the brake lines still attached.

Step3 – Secure Master Cylinder on a Work Bench

Position the maser cylinder on a work bench or table and make sure it is supported properly. Another idea is to use a vise and position the mounting flange between the jaw clamps. Position the attachments for the brake hoses to the fluid reservoir upward. Do not use too much force when clamping the master cylinder.

Step 4 – Fill Reservoir with Fresh Brake Fluid

Connect the hoses from the fluid reservoir to the master cylinder. Make sure they are secure and slightly above the master cylinder to allow easy flow of the fluid. Put fresh brake fluid in the reservoir, let it fill it up to the seam and do not replace the cap.

Give the new set up about 15 minutes. Watch out for when the fluid starts to drip from the plastic fittings.

Step 5 – Start Bleeding Master Cylinder

Get two clear 18 inch long plastic tubes and connect them at the end of both fittings. Fix the other end of the tubes into a jar about 1/3 full of brake fluid. Position the jar so that the tubes are slightly higher than the fittings in the master cylinder.

Firmly but gently, push the piston in about one inch in the master cylinder using a screw driver. Do not go further than this and repeat the process until the bubbles gradually decrease in size and dissipate. The amount of brake fluid in the jar should increase.

Step 6 – Remove Brake Fluid

Remove brake fluid out of the reservoir and disconnect hoses from the master cylinder. Reinstall it in the car as well as all the other components. Make sure all parts are fastened properly and secure.

Reattach reservoir hoses and fill the fluid reservoir with fresh brake fluid. Check the level after a while and top it up again. Adjust the brakes and bleed the brakes all around.