How Brake Bleeding Works

Preparations for Bleeding Brakes

Now that you've got your supplies, you can begin to prepare for the actual bleed. Conveniently, no matter which method you use, the same basic supplies apply. The day before you plan to bleed the brakes, consider applying penetrating oil to the bleeder valves to loosen them. These valves are hollow so you don't want to apply too much force — and don't tap them with a hammer, as this could cause damage. Gather a bunch of old rags to have on hand. Brake fluid ruins paint the moment it makes contact. To prevent damage, use the rags to clean any (inevitable) spills or drips right when they occur.

On the day of the bleed, place the vehicle on jack stands or a lift, and ensure the vehicle is secure. Remove all four wheels, then tighten one lug nut back against each rotor and place a square of lumber under the brake pedal to keep it from falling to the floor when you start bleeding the brakes. [source: Comeskey, Allen]


Refill the reservoir with fresh fluid before starting, and be sure to refill the reservoir throughout the bleeding process, keeping the fluid level above the seam at all times. Replace the reservoir cover each time you top off the reservoir. [source: Allen]

Connect the plastic tubing from the first bleeder valve to a disposable bottle on the floor. Make sure your tubing is long enough to reach the bottle without having to worry about it coming out of the bottle while you work. If this is your first time bleeding brakes, add a couple of inches of new fluid to the bottle, and keep the end of the tubing in the fluid to prevent air from sucking back up into the system.