Brake Master Cylinder: Service and Repair
WM 471519 Removing and installing brake master cylinder (HBZ)
Preliminary work
1. Remove both wiper arms -> 922519 Removing and installing wiper arm - section on "removing" 922519 Removing and installing wiper arm.
2. Remove cover in engine compartment -> 700219 Removing and installing front cover (engine compartment) - section on "removing" Service and Repair.
3. Remove cowl panel -> 664419 Removing and installing cowl panel - section on "removing" Service and Repair.
Removing the brake master cylinder
Information
- Before disconnecting the connector from the brake master cylinder (pressure sensor) first wipe off any moisture with a lint-free cloth.
- Brake lines are to be sealed with suitable plugs.
- In order to catch escaping brake fluid, place a cloth under the brake booster.
Information
- In the case of assembly work on the hydraulic connections, the electrical plug connections on the brake master cylinder must always be connected. This prevents the plug connections on the brake master cylinder and the inside of the plugs being splashed with brake fluid or water.
- Clean any plug connections that have become dirty or damp during removal or fitting with a lint-free cloth.
- Brake fluid on electrical contacts (even thinned brake fluid) leads to corrosion and may cause faults in the system.
- Remove any escaping brake fluid immediately; if necessary, rinse with water and dry.
The brake master cylinder is located on the left in the engine compartment, under the cowl panel cover -arrow- on the brake booster.
1. Push both connectors -arrows- on the plenum panel (oxygen sensor cable) from the bracket.
2. Open the cable clip on the plenum panel and loosen the cable.
3. Remove left plenum panel partition.
4. Disconnect the connector on the cover of the brake fluid reservoir and remove the cover -arrow-.
5. Remove the brake fluid from the brake fluid reservoir by suction. To do this, use a double-acting hand pump.
6. Bend both => see figure lugs on the brake fluid reservoir carefully outward and pull off the container upwards.
7. Loosen the brake lines from the brake master cylinder.
8. Unclip the brake line on the brake master cylinder to the left front wheel and remove the fastening clip -arrow-.
9. Remove the brake master cylinder from the brake booster.
10. Remove the connector of the pressure sensor at the underside of the brake master cylinder.
Installing the brake master cylinder
DANGER
Porsche Stability Management does not work without values for the current brake pressure.
- Danger of personal injury and material damage when the hydraulic unit is not calibrated.
-> After assembly of the brake master cylinder or hydraulic unit, the pressure sensor must be calibrated with the Porsche System Tester.
-> To do this, calibrate the pressure sensor in the menu ]] PSM ]] Calibration ]] Pressure sensor [[.
-> The security code is stored under menu ]] PSM ]] Actual values ]] Security code [[. The code is entered in the last four positions.
Information
- Cleanliness is essential when installing the brake master cylinder so that dirt does not enter the system. This can cause faults in the system.
- Replace worn sealing rings.
- Pay attention to tightening torques -> 47 Tightening torques for brake hydraulic system - section on "Technical values".
Install in reverse order.
1. Connect the connector of the pressure sensor to the underside of the brake master cylinder.
2. Fit the brake master cylinder loosely on the brake booster. Ensure sealing ring is seated properly between the brake master cylinder and the brake booster. Insert pushrod in the correct position in the brake master cylinder.
3. Loosely fit brake lines of brake master cylinder.
4. Fit the brake master cylinder on the brake booster and fit the brake lines. Fit the brake line of the left front wheel with the clip to the brake master cylinder.
5. Attach the brake fluid reservoir (observe sealing rings) and check for correct seating of the lugs.
6. First insert the seal of the plenum panel and then slide the plenum panel in from above. Fit the fastening screws.
7. Lay the cable and fit into clip on plenum panel.
8. Push the two large connectors into the bracket on the plenum panel.
9. Connect the connector to the cover of the brake fluid reservoir.
Subsequent work
1. Fit the right and the rear covers -> 700219 Removing and installing front cover (engine compartment) - section on "installing" Service and Repair and the cowl panel -> 664419 Removing and installing cowl panel - section on "installing" Service and Repair.
2. Install both wiper arms -> 922519 Removing and installing wiper arm - section on "installing" 922519 Removing and installing wiper arm.
3. Bleed the vehicle -> 470107 Bleeding the brake system - section on "bleeding" Service and Repair. After the bleeding operation, do not top up the brake fluid level above -MAX-.
4. Calibrate the pressure sensor with the Porsche System Tester.