Bleeding The Brake System

Information 

• Check brake fluid quality. Only use new DOT4 brake fluid (Hydraulan 404). 
• The brake fluid change interval for DOT4 brake fluid (Hydraulan 404) is 2 years. 

Information 

• To check the escaping brake fluid, ensure absolute cleanliness and make sure there are no air bubbles. 
• A transparent hose and a collecting bottle must be used to determine the amount of brake fluid used. 

1. > VAS 6860 - Brake filling and bleeding equipment  must be connected. >Connecting bleeding device to the reservoir 

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   Connecting bleeding device to the reservoir

   1. 1.1 Open the brake fluid reservoir.
   2. 1.2 >VAS 6860 - Connect brake filling and bleeding equipment  to the reservoir and switch on.
   3. 1.3 Set the bleeding pressure to 2.0 bar.
2. Perform the first bleeding procedure (general bleeding) in the sequence -1 to 4-  (only using >VAS 6860 - brake filling and bleeding equipment  ).

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   First bleeding procedure

   1. 2.1 Open the outer bleeder screw -A -  .
   2. 2.2 As soon as clear, bubble-free brake fluid emerges, close the outer bleeder screw -A -  .
   3. 2.3 Open the inner bleeder screw -B -  .
   4. 2.4 As soon as clear, bubble-free brake fluid emerges, close the inner bleeder screw -B -  .

   Information 

   High brake fluid loss when bleeding:

   • Make sure that there is sufficient brake fluid left (the reservoir must not run dry). 
   • Empty the collecting bottle after every bleeding procedure. 
3. Perform second bleeding process in the sequence -1 to 4-  (using >VAS 6860 - brake filling and bleeding equipment  and PIWIS Tester).

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   Second bleeding procedure

   1. 3.1 Connect the PIWIS Tester  to the vehicle and start it. Switch on ignition.
   2. 3.2 Start the diagnostic  software.
   3. 3.3 Select brake booster  control unit.
   4. 3.4 Select the Maintenance/repairs  menu.
   5. 3.5 Press F12 to select the start-up function  .
   6. 3.6 Follow the instructions on the PIWIS Tester  .

   Information 

   As soon as the brake system has been opened, the secondary circuit must also be bled on vehicles with electronic brake booster. This does not apply when you are just changing the brake fluid.

   Information 

   You will need another person to help by pressing the pedal!

   Information 

   High brake fluid loss when bleeding:

   • Make sure that there is sufficient brake fluid left (the reservoir must not run dry). 
   • Empty the collecting bottle after every bleeding procedure. 
4. Perform the third bleeding procedure (additional bleeding of the secondary circuit) in the sequence -1 to 4-  (using the >VAS 6860 - brake filling and bleeding equipment  , pressing the brake pedal and using the PIWIS Tester).

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   Third bleeding procedure

   1. 4.1 Connect the PIWIS Tester  to the vehicle and start it. Switch on ignition.
   2. 4.2 Start the diagnostic  software.
   3. 4.3 Select Porsche Stability Management (PSM)  control unit.
   4. 4.4 Select the Maintenance/repairs  menu.
   5. 4.5 Press F12 to select the service bleeding  function.
   6. 4.6 Follow the instructions on the PIWIS Tester  .
5. Fit and tighten each bleeder screw after bleeding the system.

   Front bleeder valves (grey cast iron): >Tightening torque 14 Nm (10.3 ftlb.) 

   Front bleeder valves (PCCB): >Tightening torque 20 Nm (14.8 ftlb.) 

   Rear bleeder valves (grey cast iron): >Tightening torque 14 Nm (10.5 ftlb.) 

   Rear bleeder valves (PCCB): >Tightening torque 14 Nm (10.5 ftlb.) 

   Information 

   The brake fluid level in the reservoir must be between the MIN and MAX markings after bleeding the brake system.

6. Disconnect >VAS 6860 - brake filling and bleeding equipment  from the vehicle.
   1. 6.1 Check brake fluid level and correct it if necessary.
   2. 6.2 Close the cap on the brake fluid reservoir.
7. Use the PIWIS Tester  to commission the electric brake booster.
   1. 7.1 Select brake booster  control unit.
   2. 7.2 Select the Maintenance/repairs  menu.
   3. 7.3 Press F12 to select the start-up function  .
   4. 7.4 Follow the instructions on the PIWIS Tester  .
8. Start the vehicle electrically and create a vacuum in the electric brake booster. Check brake-pedal travel and pedal feel.

   Information 

   You will need another person to help by pressing the pedal!

   Information 

   The brake fluid level in the reservoir must be between the MIN and MAX markings after bleeding the brake system.

9. If the pedal travel is too long or if the pedal feels too soft, perform a fourth bleeding process (to remove remaining air bubbles) in the sequence -1 to 4-  (using >VAS 6860 - brake filling and bleeding equipment  by actuating the brake pedal and using a rubber hammer).

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   Fourth bleeding process (only if pedal does not feel OK)

   1. 9.1 >VAS 6860 - Brake filling and bleeding equipment  must be connected. >Connecting bleeding device to the reservoir 

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      Connecting bleeding device to the reservoir

      1. 9.1.1 Open cap on brake fluid reservoir.
      2. 9.1.2 >VAS 6860 - Connect brake filling and bleeding equipment  to the reservoir and switch on.
      3. 9.1.3 Set the bleeding pressure to 2.0 bar.
   2. 9.2 Open the outer bleeder screw -A -  .
   3. 9.3 Repeat the following procedure five times (per brake calliper).
      1. 9.3.1 Slowly press the brake pedal fully and keep it pressed for 2 to 3 seconds.
      2. 9.3.2 Slowly release the brake pedal until the brake pedal is back in its initial position.
      3. 9.3.3 Gently tap the brake calliper using a rubber hammer while pressing the brakes.
      4. 9.3.4 After pressing the brakes for the fifth time, keep the brake pedal pressed and close the outer bleeder screw -A -  .
   4. 9.4 Open the inner bleeder screw -B -  .
   5. 9.5 Repeat the following procedure five times (per brake calliper).
      1. 9.5.1 Slowly press the brake pedal fully and keep it pressed for 2 to 3 seconds.
      2. 9.5.2 Slowly release the brake pedal until the brake pedal is back in its initial position.
      3. 9.5.3 Gently tap the brake calliper with a rubber hammer while doing this.
      4. 9.5.4 After pressing the brakes for the fifth time, keep the brake pedal pressed and close the inner bleeder screw -B -  .
   6. 9.6 Screw in and tighten each bleeder screw after bleeding the system.

      Front bleeder valves (grey cast iron): >Tightening torque 14 Nm (10.3 ftlb.) 

      Front bleeder valves (PCCB): >Tightening torque 20 Nm (14.8 ftlb.) 

      Rear bleeder valves (grey cast iron): >Tightening torque 14 Nm (10.5 ftlb.) 

      Rear bleeder valves (PCCB): >Tightening torque 14 Nm (10.5 ftlb.) 

   7. 9.7 Disconnect >VAS 6860 - brake filling and bleeding equipment  from the vehicle.
      1. 9.7.1 Check brake fluid level and correct it if necessary.
      2. 9.7.2 Close the cap on the brake fluid reservoir.
10. Start the vehicle electrically and create a vacuum in the brake booster. Check brake-pedal travel and pedal feel.

    If the pedal travel is too long or if the pedal feels too soft, carry out the bleeding procedures again.