How to Vacuum Bleed Your Brakes

In a lot of cases vacuum bleeding can be just as effective as pressure bleeding the brake system. Speedway Motors offers an extremely simple and easy to use Mityvac, hand operated vacuum/pressure pump under part number 91083895. The vacuum pump is an extremely versatile service tool that can be used to perform a number of useful tasks. The pump and its accessories are useful to transfer fluids, help to bleed brakes and aid in other tasks.

• Always make certain that the master cylinder reservoir is filled and that a supply of new, clean fluid of the proper type is on hand to top off the reservoir as the fluid level drops during bleeding.
• Slip 1 1/2” of tubing between the pump and the lid of reservoir jar at port marked “TO PUMP” and attach the 31/2” plastic hose to the bottom of the cap.
• Affix at least a 12” piece of tubing to the other reservoir jar port. Be certain that the cover of the reservoir jar is secure.
• Select the appropriate adapter(s). The L-shaped universal adapters should fit snugly over the brake bleeding fitting in order to seal properly. The tapered adapters fit inside the thru-hole of fitting and will generally seal well when inserted tightly with a pressing and twisting motion. Attach adapter to reservoir hose.
• Place wrench on brake bleeding fitting. Attach adapter and pump assembly, and pump 10 to 15 times.
• After evacuating about 2-inches of fluid into the jar, close the fitting and refill the master cylinder with new brake fluid. Repeat all previous steps on all remaining wheels.
• If fluid is not drawn into the jar after opening the fitting, make certain the lid of the jar is tight. You will not be able to produce the necessary vacuum in the jar if the lid does not fit securely. Occasionally some dirt will get into the brake line, in which case the pump may not be totally effective. If this happens, have someone touch the brake pedal once lightly, with the bleeding valve open, then proceed to use the pump.
• Before test-driving, check the pedal, it should feel firm when depressed and it should hold constant pressure without dropping.