Brake Bleeding: Service and Repair

Overview
Bleeding brakes (vehicle with PSM)
PSM (Porsche Stability Management) is standard in the 911 Turbo (996).

Note:
^ Observe brake-fluid quality. Use only new DOT 4 brake fluid.
^ The brake-fluid change interval using Super DOT 4 brake fluid is two years.


Procedure for bleeding
1. Bleed brakes as usual.
2. Then bleed at front on right with running booster pump.


1st Step: Bleed Brakes As Usual

Caution:
^ For vehicles with extremely high mileage or for very old vehicles, damage to the brake master cylinder can occur and the primary boots can be damaged.
^ Double the number of pumping cycles and use only half of the master brake cylinder stroke.

1. Fill reservoir to its top edge with new brake fluid.





2. Connect a bleeding device to the brake fluid reservoir. Switch on the bleeding device. Bleeding pressure approximately 2.0 bar.

Note: Bleed the outer bleeder valve first.

3. Continue bleeding at the brake calipers in the sequence: Sequence: Rear right / rear left / front left / front right.
4. Open each bleeder valve until clear, bubble-free brake fluid emerges.
5. Use a transparent hose and a collecting bottle to check the escaping brake fluid accurately for cleanliness, lack of air bubbles and to determine the brake fluid used.
After installing a new brake master cylinder and/or a new hydraulic unit, do the following while bleeding:
^ Open the right rear bleeder valves, then fully depress the brake pedal several times.
^ Hold for 2 - 3 seconds after each depression, then release slowly.
^ Repeat this procedure in the sequence rear left / front right front left. This will remove all air bubbles (from the primary circuit).

Note: Also carry out this procedure if the brake hydraulics was largely empty or if after bleeding residual air can be detected by excessive brake-pedal travel.

6. Continue bleeding at front on right with running booster pump (Step 2).

2nd Step: Bleeding At Front On Right With Running Booster Pump

Caution: For vehicles with extremely high mileage or for very old vehicles, damage to the brake master cylinder can occur and the primary boots can be damaged.

^ Double the number of pumping cycles and use only half of the master brake cylinder stroke.

Note:
^ Bleed brakes as usual
^ Do not carry out booster pump activation with the Porsche System Tester 2 until after this has been done (after conventional bleeding) as otherwise damage to the booster pump can occur.
^ To bleed at front on right with running booster pump the bleeding device remains connected (switched on). Bleeding pressure approximately 2.0 bar.

1. Connect the Porsche System Tester 2 to the diagnostic socket.
2. Switch ignition on. Select the "Bleed" menu in the PSM system. Entry takes place through the ABS system (automatic status change after PSM).
3. Open the front right bleeder valve (use hose and collecting bottle).

Note: After a certain period of time has elapsed, the Tester switches off automatically (leaves the menu). If necessary, continue the procedure after a certain waiting time (select Bleed menu again)

4. Press the Start button on the System Tester. In this way the booster pump is activated.
5. Bleed until clear, bubble-free brake fluid emerges.
6. In addition (throughout bleeding operation) fully depress (pump) brake pedal as far as the stop at least ten times.
7. Close the right front bleeder valve. Then immediately press the Stop button on the System Tester. In this way pump operation is ended.
8. Switch ignition off and disconnect System Tester.





9. Switch off and disconnect the bleeding device. Correct the brake fluid level if necessary.