Power Brake Booster
WARNING: This page is about a different car, the 2004 MINI Cooper, 2003 MINI Cooper, and 2002 MINI Cooper. However, it is still accessible from the selected car via links, so may be relevant.
Release clamp and detach vacuum hose. Connect Tester (343100) between connection and vacuum non-return valve. Start engine. Check whether a vacuum forms. Switch off engine. Depress brake pedal to set a maximum value of .86 bar, then wait until the value stabilizes. When the brake pedal is not depressed, the value may drop by a maximum of .06 bar within a test period of one minute. See Fig 1.