911 Carrera 4S Coupe AWD F6-3600cc 3.6L SOHC (1997)
brake master cylinder.
Note
Also carry out this operation if the hydraulic brake system has been drained virtually completely or if air is found to remain trapped in
the system after bleeding (e.g. if pedal travel is excessive).
Caution:
Double the pumping cycles on high-mileage vehicles or older vehicles but use only half the brake master cylinder stroke in these cases (to avoid
damage to the master cylinder, i.e. primary cups).
-
Switch off and disconnect bleeding device. Top up brake fluid if required.
Note
When replacing the hydraulic unit on vehicles with ABD (Automatic Brake Differential) or if the hydraulic unit has been removed, the ABD
circuit (in the hydraulic unit) must be bled as well. Refer to Bleeding the ABD Circuit.
Bleeding the ABD Circuit
-
Preparatory operations: Bleed brakes in conventional manner.
-
Leave the bleeding device connected (switched on) to bleed the ABD circuit. Bleeding pressure approx. 1.5...2.0 bar. Overflow hose (for
venting) on expansion tank is clamped off with a hose.
-
Connect System Tester 9288 to the diagnostic socket. Switch on ignition. Select "Bleed" menu.
-
Open right-hand rear bleeder valve (use recipient bottle).
-
Press Start button on System Tester. This causes certain functions in the hydraulic unit to be started (return feed pump, ASV valve and USV
valve are triggered).
Bleed until the escaping brake fluid is free from air bubbles.
Additionally and during the whole bleeding process, depress brake pedal (at least 10 times) across the full pedal stroke (to the pedal stop)
(pumping).
Warning: On high-mileage or older vehicles, double the pump cycles and use only half the brake master cylinder stroke (to avoid damage to the
master brake cylinder/primary cup).
-
Close right-hand rear bleeder valve. Then immediately actuate Stop button taste on System Tester.
-
Switch off ignition and disconnect System Tester.
-
Correct brake fluid level if required.
