Low Pressure Test
WARNING: This page is about a different car, the 2004 BMW Z4 and 2003 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.
Detach hose from connection piece. Install Vacuum Tester (34 3 100) between connection piece and vacuum hose of non-return valve. See Fig 1 . Start engine. Check buildup of partial vacuum. Switch off engine. Press the brake pedal to set a vacuum pressure of not more than 11.6 psi (0.8 bar) and wait for the value to stabilize. When the brake pedal is not pressed, the vacuum pressure is permitted to drop over a test period of one minute by a maximum of .87 psi (0.06 bar). If specified values are not reached:
- Check line connections for vacuum seal.
- Replace vacuum non-return valve.
- Check seal between brake booster and brake master cylinder (sealing ring) for perfect condition and correct seating.
- If specified values are not achieved when test is repeated, replace brake booster. See BRAKE BOOSTER under REMOVAL & INSTALLATION.