A brake bleeder kit is a tool set used to purge air from hydraulic brake systems. Any air bubble trapped inside brake lines will compress under pressure, causing a spongy brake pedal and reduced stopping power. The standard two-person brake bleed requires one person to pump the pedal while another cracks the bleeder screw. The bleeder kit allows a single mechanic to do the job using vacuum pressure or a one-way check valve.
A vacuum bleeder kit uses a handheld pump to draw brake fluid out through the caliper bleeder screw, pulling air bubbles with it. A pressure bleeder connects to the master cylinder reservoir, pushing fresh fluid down through the lines. To get a clean job, wrap the threads of the bleeder screw with Teflon tape. This stops air from leaking past the threads and entering the catch hose, which can make it look like there is constant air in the line.