Hydraulic Components - Brake System (avant) Audi A4 B8

BRAKE SYSTEM, BLEEDING

Note. Only use new brake fluid conforming to US-Norm FMVSS 116 DOT 4. Genuine VW/Audi brake fluid conforms to this specification. Do not use any silicone-based fluid. Avoid contaminating brake fluid with particles or lint (e.g. from cleaning cloths). Rinse off spills, by using plenty of water. Do not work with compressed air and do not move vehicle while the system is open. During the final road test, ensure that a ABS-controlled brake test is performed at least once (pulsation must be felt at the brake pedal). The brake system indicator light blinks when the brake fluid is too low or the ABS system or parking brake is malfunctioning.

Bleeding Procedure

Note. There must be a positive pressure of 2 bar to bleed the ABS Hydraulic Unit -N55-. Pressure setting must be checked at bleeder device. Only place brake pedal load device on brake system during assembly, then bleed.

Special tools and workshop equipment required

1. Brake filler bleeder unit VAS 5234
2. Adapter VAS 5234/1

Bleed the brake system with the brake filler bleeder unit VAS 5234 with the adapter VAS 5234/1

Follow Brake filler bleeder unit VAS 5234 operating instructions.

Remove plenum chamber cover Removal and Installation .

Raise vehicle.

Connect Brake filler bleeder unit VAS 5234 with adapter VAS 5234/1.

Open bleeder screws in the specified sequence and bleed (support with pedal pressure if necessary).

Bleeding sequence

1 - Left front brake caliper

2 - Right front brake caliper

3 - Left rear brake caliper

4 - Right rear brake caliper.

Bleed until brake fluid comes out with no bubbles and foam.

Close bleeder screws.

Lower vehicle.

Install plenum chamber cover Removal and Installation .

BRAKE FLUID, CHANGING

Brake Fluid, Changing

Refer to appropriate service information.

BRAKE LINE ROUTING

Brakes and brake lines are delivered as ready-to-install replacement parts.

Secure brakes and brake lines at original fastening points when installing.

Lines to hydraulic assembly

Items -1- through -4- hex nuts (-M10- and M12 dia. 5 mm brake lines), 12 Nm tightening specification.

Items -5- and -6- hex nuts (-M14- dia. 8 mm brake lines), 16 Nm tightening specification.

Scheme 143

Brake hose to brake caliper to front axle

Item -1- brake hose, ensure retaining tabs are seated correctly in bracket.

Item -2- retaining spring.

Item -3- brake line, 17 Nm tightening specification.

Scheme 144

Item -1- brake line, 17 Nm tightening specification.

Item -2- retaining spring.

Item -3- brake hose, ensure retaining tabs are seated correctly in bracket.

Scheme 145

Brake line routing in wheel housing to front axle

Item -1- brake line, 12 Nm tightening specification.

Item -2- intermediate piece.

Item -3- brake line, 12 Nm tightening specification.

Scheme 146

Brake line connecting in wheel housing to front axle

Item -1- brake hose bracket.

Item -2- brake line, 12 Nm tightening specification.

Scheme 147

Brake line routing to rear axle

Item -1- brake hose, 12 Nm tightening specification.

Item -2- brake hose bracket, ensure retaining tabs are seated correctly in bracket.

Item -3- retaining spring.

Item -4- brake line, 12 Nm tightening specification.

Scheme 148

DESCRIPTION AND OPERATION

FN3

FBC

FN3 BRAKE CALIPER ASSEMBLY OVERVIEW

Note. Install complete repair kit when servicing. New brake calipers are filled with brake fluid and are pre-bled. Apply thin coat of assembly paste G 052 150 A2 to brake cylinders, pistons and seals.

Scheme 149

1. Caps Remove guide pins to remove. Insert guide pins after installation.
2. Guide pins 30 Nm Replace «BUSHING AND GUIDE PINS, REPLACING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__bushing-and-guide-pins-replacing)
3. Bleeder valve Apply a thin coat of assembly paste G 052 150 A2 to threads before screwing in. 10 Nm
4. Protective cap Push onto bleeder valve
5. Brake caliper housing
6. Retaining spring Insert with both ends in holes of brake caliper housing NOTE: Retaining spring must be pressed under brake carrier after it is inserted in both holes. If improperly installed, the wear of the outer brake pad cannot be adjusted, thereby increasing brake pedal travel.
7. Bushing Insert in brake caliper housing Replace «BUSHING AND GUIDE PINS, REPLACING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__bushing-and-guide-pins-replacing)
8. Brake carrier Bolt to brake caliper housing
9. Seal
10. Pistons First apply thin coat of brake cylinder paste G 052 150 A2 on piston Diameter 57 mm.
11. Protective cap Do not damage the piston when inserting it.

FBC BRAKE CALIPER ASSEMBLY OVERVIEW

Note. Install complete repair kit when servicing. Apply thin coat of assembly paste G 052 150 A2 to brake cylinders, pistons and seals.

Scheme 150

1. Bolt 30 Nm
2. Protective cap Insert in brake caliper Replacing «PROTECTIVE CAP AND GUIDE PINS, REPLACING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__protective-cap-and-guide-pins-replacing)
3. Guide pins Slide through the boot Replacing «PROTECTIVE CAP AND GUIDE PINS, REPLACING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__protective-cap-and-guide-pins-replacing)
4. Protective cap Install on the bleeder valve.
5. Bleeder valve Apply a thin coat of assembly paste G 052 150 A2 to the threads before screwing in. 15 Nm
6. Brake caliper housing
7. Retaining spring Ensure installation position is correct.
8. Protective cap Do not damage when installing piston Coat with Assembly paste G 052 150 A2
9. Pistons First apply thin coat of brake cylinder paste G 052 150 A2 on piston Diameter 57 mm.
10. Seal Coat with assembly paste G 052 150 A2.
11. Brake carrier Removing and Installing «BRAKE CALIPER WITH FRONT BRAKE CARRIER»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#mechanical-components-brake-system-avant) The 4 retaining pins for the brake pads on the brake carrier must not be loosened under any circumstances.
12. Bolt 196 Nm

ELECTRONIC PARKING BRAKE REAR CALIPER ASSEMBLY OVERVIEW

Note. When servicing, install entire repair kit. Apply thin coat of assembly paste G 052 150 A2 to brake cylinders, pistons and seals.

Scheme 151

1. Self-locking bolt 35 Nm Always replace Counterhold at guide pin when loosening and tightening.
2. Brake caliper housing with actuator
3. Bleeder valve 10 Nm
4. Dust cap Push onto bleed valve
5. Seal Removing and installing «REAR BRAKE CALIPER PISTON»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__rear-brake-caliper-piston)
6. Pressure nut To operate parking brake
7. Pistons Removing and installing «REAR BRAKE CALIPER PISTON»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__rear-brake-caliper-piston)
8. Guide pins Grease before pulling on protective cap Delivered as a replacement part with sufficient grease. Replacing «REAR BRAKES GUIDE PINS AND PROTECTIVE CAPS, REPLACING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__rear-brakes-guide-pins-and-protective)
9. Protective cap Pull onto brake carrier and guide pin. Replacing «REAR BRAKES GUIDE PINS AND PROTECTIVE CAPS, REPLACING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__rear-brakes-guide-pins-and-protective)
10. Brake carrier with guide pins and protective cap Supplied as pre-assembled replacement part with sufficient grease on guide pins If protective caps or guide pins are damaged, install repair kit. Use grease packet supplied to lubricate guide pins.
11. Protective cap Removing and Installing «REAR BRAKE CALIPER PISTON»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__rear-brake-caliper-piston) Pull onto the piston with the outer sealing lip.

BRAKE BOOSTER/BRAKE MASTER CYLINDER ASSEMBLY OVERVIEW

Note. Master brake cylinders can no longer be disassembled, servicing is not possible. Use only new brake fluid. Observe information on brake fluid reservoir!

Scheme 152

1. Brake fluid reservoir Do not remove screen in brake fluid reservoir. Removing and Installing «BRAKE FLUID RESERVOIR»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__brake-fluid-reservoir)
2. Brake fluid reservoir cover Not installed in all vehicles. Removing and Installing «BRAKE FLUID RESERVOIR COVER»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__brake-fluid-reservoir-cover) NOTE: The cover is not installed on all vehicles.
3. Sealing cap with seal and brake fluid lever warning switch --F34
4. Bolt 5 Nm
5. Wiring to the clutch master cylinder
6. Brake Booster Adjusting ball head (Scheme 153) Function test: With engine switched off, depress brake pedal firmly several times (to deplete vacuum in tool). Depress and hold brake pedal with average foot pressure and start engine. If brake booster is working properly, pedal will be felt to give noticeably under foot (booster assistance becomes effective). With adhesive seal If malfunctioning: replace as complete unit. Removing and Installing «BRAKE BOOSTER»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__brake-booster)
7. Pedal support bolt 20 Nm
8. Brake pedal Removing and Installing, with Manual Transmission «BRAKE PEDAL, WITH MANUAL TRANSMISSION»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#mechanical-components-brake-system-avant__brake-pedal-with-manual-transmission) Removing and Installing, with Automatic Transmission «BRAKE PEDAL, WITH AUTOMATIC TRANSMISSION»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#mechanical-components-brake-system-avant__brake-pedal-with-automatic-transmission)
9. Brake lamp sensor Removing and Installing «BRAKE LAMP SENSOR»(/audi/a4/b8-2007-2012/remont/anti-locktraction-control/#anti-lock-brake-system-avant__brake-lamp-sensor)
10. Bolt Connects brake booster to the mounting bracket 25 Nm
11. Hex nut For brake master cylinder 49 Nm
12. Brake line Brake master cylinder to hydraulic unit 16 Nm
13. Brake line Brake master cylinder to hydraulic unit 16 Nm
14. Seal Replace
15. Brake Master Cylinder Cannot be serviced. Replace as complete unit if malfunctioning. Removing and Installing «BRAKE MASTER CYLINDER»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__brake-master-cylinder)
16. Sealing plugs Moisten with brake fluid and press into brake fluid reservoir

Note. Use only new brake fluid. Observe information on brake fluid reservoir!

Scheme 153

a = 164.7mm ± 0.5mm

Note. Surface -1- for measuring. When measuring, ball head must be arranged at a right angle to surface of brake booster. Measure to end of ball head without gasket installed.

Ball head to the push rod, 30 Nm.

VACUUM PUMP ASSEMBLY OVERVIEW

Note. Only the vacuum pump is shown in the illustration and not the installation location

Scheme 154

1. Bolt 9 Nm Remove to remove pump. NOTE: The pump is not designed to be disassembled.
2. Vacuum pump
3. Vacuum hose Secure with hose clamps that match those used in production.
4. Bolt 5 Nm NOTE: Installing the bolt depends on the model. Alternatively, secure the vacuum hose with the hose clamp for the vehicle version.
5. O-Ring Replace NOTE: Installation of the O-ring depends on the model.
6. O-Ring Replace NOTE: Installation of the O-ring depends on the model.
7. O-Ring Replace NOTE: Installation of the O-ring depends on the model.

The construction of the vacuum pump V192 depends on the engine.

The electrical vacuum pump V192 is switched on by the engine control module depending on the intake line pressure.

Scheme 155

1. Vacuum line
2. Electrical connector
3. Brake System Vacuum Pump -V192- Removing and Installing «VACUUM PUMP»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__vacuum-pump) Checking «BRAKE SYSTEM VACUUM PUMP, CHECKING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__brake-system-vacuum-pump-checking)
4. Check valve Removing and Installing Checking «CHECK VALVE, CHECKING»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__check-valve-checking)
5. Vacuum pump V192 bracket Removing and Installing «VACUUM PUMP BRACKET»(/audi/a4/b8-2007-2012/remont/mechanical-hydraulic/#hydraulic-components-brake-system-avant__vacuum-pump-bracket)
6. Bracket nut 20 Nm

BRAKES, TESTING FOR LEAKS

Note. The hydraulic brake system must be bled. Only install genuine parts or components approved by Audi in the brake system. If the brake fluid replacement interval specified by Audi is exceeded, replace the brake fluid. Check the system visually for leaks. Fix leaks and remove dirt on the hydraulic system.

Switch engine off.

Press brake pedal until there is no more brake assistance - "pump the brake booster empty". The brake pedal becomes hard.

Press brake pedal about 20 mm out of resting position.

Hold the force on the pedal steady for about 20 seconds.

The brake pedal travel must not increase.

Release brake pedal.

Press firmly on brake.

Hold the force on the pedal steady for about 20 seconds.

The brake pedal travel must not increase.

If the pedal sinks down during one of the tests, repeat the visual inspection on the brake system.

If no leaks are found, the brake master cylinder probably has leaks and must be replaced.

HIGH AND LOW PRESSURE TESTING

Special tools and workshop equipment required

1. Brake Pressure Gauge 0-250 bar V.A.G 1310A

Before beginning

Check brake system (brake master cylinder, brake hoses, brake lines and brake calipers) for leaks and function.

High pressure testing

Remove bleeder screw at one of the front brake calipers. Connect brake pressure gauge V.A.G 1310A and bleed.

Scheme 156

Install brake pedal loading device V.A.G 1869/2 between brake pedal and driver seat.

Scheme 157

Apply pressure to brake pedal until the gauge indicates a pressure of 50 bar.

The pressure must not drop by more than 4 bar during the test period of 45 seconds.

If pressure drop is large, replace hydraulic unit.

Low pressure testing

Push brake pedal loading device V.A.G 1869/2 back until pressure gauge indicates 6 bar positive pressure.

The pressure must not drop by more than 1 bar during a test period of 3 minutes.

If pressure drop is large, replace hydraulic unit.

BRAKE SYSTEM VACUUM PUMP, CHECKING

Description and function

The electrical vacuum pump is switched on by the engine control module depending on the intake line pressure.

Vacuum pump has On Board Diagnostic (OBD) properties. Detected faults are stored in engine control module.

Note. The function of the electrical vacuum pump can only be checked using OBD when the engine is switched off.

Special tools and workshop equipment required

1. Connect Vehicle Diagnostic, Testing and Information System VAS 5051B or VAS 5052.

Scheme 158

Procedure

Switch ignition off.

Press the brake pedal until there is no more brake assistance - "pump brake booster empty". The brake pedal becomes hard.

Connect vehicle diagnosis, testing and information system VAS 5051B or VAS 5052 to 16-pin Data Link Connector (DLC) in the vehicle with the ignition switched off.

Switch on Vehicle Diagnostic, Test And Information System.

The tester will now require up to 3 minutes to boot up.

Switch on ignition.

Select operating mode: On the display, select "Vehicle On-Board Diagnosis".

Select vehicle system: On the display, select "01 - Engine electronics".

At the upper right of the screen, the control module identification and coding are displayed.

Select diagnostic function: At this point, all diagnostic functions are available.

On the display, select "006 - Basic setting".

Press buttons 0 , 0 and 8 .

Confirm input with Q button.

Displayed at the bottom of the screen

Select "Activate" in the display to begin the test.

Displayed at the bottom of the screen

The brake pedal may no longer be actuated once the test begins.

The brake system vacuum pump -V192- supplies the brake booster with vacuum. At the same time, the control module performs a diagnosis of the brake booster system.

If the pressure within in the brake booster reaches the cut-off threshold by the time that was predetermined by the diagnostic function, the test has been passed.

Displayed at the bottom of the screen

Using the Go to button, the operating mode can be interrupted or ended.

If the pressure within the brake booster does not reach the cut-off threshold by the time that was predetermined by the diagnostic function, the test has failed.

Displayed at bottom of the screen

Perform "Guided Fault Finding" with the vehicle diagnosis, testing and information system VAS 5051.

The ignition must be switched off and on to repeat the test.

CHECK VALVE, CHECKING

Valve must allow air to flow in direction of arrow.

Valve must remain closed in opposite direction.

Observe correct installation position.

The arrow points to the vacuum pump.

REMOVAL AND INSTALLATION

FN3

FBC

FRONT BRAKE CALIPER PISTON

Special tools and workshop equipment required

1. Trim Removal Wedge 3409.
2. Piston Resetting Tool T10145.
3. Assembly Paste G 052 150 A2.

Removing

Force piston from brake caliper housing using compressed air.

Scheme 159

Note. Place a wooden board into the recess of the caliper housing so it is not damaged.

Remove seal.

Scheme 160

Use trim removal wedge 3409 for this.

Note. When removing, make sure that surface of cylinder is not damaged.

Installing

Insert inner seal in the brake caliper groove -arrow-.

Scheme 161

Press protective cap onto the brake caliper housing so that it contacts the brake caliper housing all around.

Scheme 162

It should no longer be possible to remove the protective cap from the brake caliper housing by hand.

Thinly coat piston and seal with assembly paste G 052 150 A2 before inserting.

Press brake piston lightly on protective cap.

Do not angle piston, to avoid damaging the seal sleeve.

Blow protective cap on with pressurized air (max. 3 bar). The protective cap will thereby jump over the brake piston.

Press brake pistons into caliper using Piston Resetting Tool T10145.

Scheme 163

Do not angle piston, to avoid damaging the seal sleeve.

Note. The inner sealing lip of the protective cap thereby slips into the groove on the piston.

BUSHING AND GUIDE PINS, REPLACING

Note. When removing, mark brake pads that will be used again. Install in the same position, otherwise braking effect will be uneven!

Removing

Loosen brake caliper at pins -12-.

Scheme 164

Remove brake caliper.

Do not let the brake caliper hang from the brake hose. Secure it to the body with suitable cable ties or wire. Do not support the weight with the brake hose.

Remove bushing from brake caliper.

Installing

Installation is in reverse sequence.

Use new guide pins.

Removing

Special tools and workshop equipment required

1. Disassembly wedge 3409
2. Piston Resetting Tool T10145
3. Assembly paste G 052 150 A2

Force piston from brake caliper housing using compressed air.

Scheme 165

Note. Place a wooden board into the recess of the caliper housing so it is not damaged.

Remove seal.

Scheme 166

Use trim removal wedge 3409 for this.

Note. When removing, make sure that surface of cylinder is not damaged.

Installing

The surface of the piston and seal must only be cleaned with mineral spirits and then dried.

Thinly coat piston and seal with assembly paste G 052 150 A2 before inserting.

Insert inner seal in the brake caliper groove -arrow-.

Press protective cap onto the brake caliper housing so that it contacts the brake caliper housing all around.

It should no longer be possible to remove the protective cap from the brake caliper housing by hand.

Thinly coat piston and seal with assembly paste G 052 150 A2 before inserting.

Press brake piston lightly on protective cap.

Do not angle piston, to avoid damaging the seal sleeve.

Blow protective cap on with pressurized air (max. 3 bar). The protective cap will thereby jump over the brake piston.

Press brake pistons into the caliper using Piston Resetting Tool T10145.

Do not angle piston, to avoid damaging the seal sleeve.

Note. The inner sealing lip of the protective cap thereby slips into the groove on the piston.

PROTECTIVE CAP AND GUIDE PINS, REPLACING

The guide pins must be removed if the protective caps are damaged.

Removing

Note. When removing, mark brake pads that will be used again. Install in the same position, otherwise braking effect will be uneven!

Press retaining spring -7- in the center.

Note. The spring is tensioned, keep hands protected. When removing the spring, make sure it does not scratch the brake caliper or damage the paint.

Remove retaining spring carefully.

Remove bolts -1- on the brake caliper.

Remove brake caliper.

Do not let the brake caliper hang from the brake hose. Secure it to the body with suitable cable ties or wire. Do not support the weight with the brake hose.

Remove protective cap -2- on the outside from the groove on guide pin.

Pull guide pin -3- outward out of the protective cap.

Remove protective cap from brake caliper.

Installing

Carefully press the guide pin into the protective cap as far as the first groove.

Insert protective cap in the brake caliper.

The protective cap must be seated in the center of the brake caliper.

Press guide pin through the protective cap.

The protective cap must not be seated in both grooves on the guide pin.

Check the movement of the guide pin. Both guide pins must slide.

Install brake caliper and tighten bolts -1- to 30 Nm.

Position retaining spring -7- on the outer brake pad.

Press retaining spring in the center and insert the center tab of the retaining spring in the hole on the brake caliper.

Note. The spring is tensioned, keep hands protected. When removing the spring, make sure it does not scratch the brake caliper or damage the paint.

The retaining spring tab must sit correctly in the hole -arrow- in the brake caliper or it can spring out and the brake pad will not be held in place.

Scheme 167

REAR BRAKE CALIPER PISTON

Special tools and workshop equipment required

1. Torque Wrench V.A.G 1331
2. Torque Wrench V.A.G 1332
3. Piston Resetting Tool T10145
4. Disassembly Wedge 3409
5. Vehicle Diagnostic, Test And Information System VAS 5051B

Removing

Remove pistons as far as possible from brake caliper

Force piston out of brake caliper housing using compressed air.

Scheme 168

Note. When removing, make sure that surface of cylinder is not damaged. Place a wooden board into the recess of the caliper housing so it is not damaged.

Remove old seal from brake caliper with Trim Removal wedge 3409.

Scheme 169

Installing

Install new seal in brake caliper.

Place new protective cap on brake pistons as shown.

Scheme 170

Install pressure nut to dimension -a- 15 mm.

Scheme 171

Insert protective cap in brake caliper groove. Use Trim Removal wedge 3409 to do so.

Scheme 172

Carefully slide brake piston into brake caliper. Move brake piston when doing so. Brake piston must be guided over pressure nut, this is only possible in four positions.

After brake piston has been guided onto pressure nut, press it as far as stop into brake caliper.

Scheme 173

Note. Ensure pressure nut is not damaged.

Install pressure nut clockwise as far as the stop.

Scheme 174

Make sure rubber makes contact around brake caliper housing -arrows

Scheme 175

Press piston into brake caliper by hand

Scheme 176

Note. The inner sealing lip of the protective cap thereby slips into the groove on the piston.

REAR BRAKES GUIDE PINS AND PROTECTIVE CAPS, REPLACING

If protective caps or guide pins are damaged, install repair kit. Use grease packet supplied to lubricate guide pins

Removing

Remove bolts -1- on brake caliper.

Remove brake caliper.

Do not let the brake caliper hang from the brake hose. Secure it to the body with suitable cable ties or wire. Do not support the weight with the brake hose.

Remove protective cap -9- from nut on the brake carrier.

Remove guide pins -8- from brake carrier.

Remove protective cap from guide pin.

Installing

Grease guide pin before inserting.

Slide protective cap over the groove on the guide pin.

Slide guide pin -8- with protective cap -9- through brake carrier.

Press protective cap over the groove on the brake carrier.

Insert brake caliper.

Install bolts -1- and tighten them.

BRAKE FLUID RESERVOIR COVER

Not installed in all vehicles.

The brake fluid reservoir cover has an opening on the left to check the brake fluid level. To prevent damage later, brake fluid must not enter between the brake fluid reservoir cover and the brake fluid reservoir.

Removing

Remove plenum chamber cover Removal and Installation .

Remove bolt -4-.

Remove brake fluid reservoir cover from vehicle.

Installing

Place brake fluid reservoir cover over the brake fluid reservoir.

Screw in bolt -4- and tighten.

Install plenum chamber cover Removal and Installation .

BRAKE FLUID RESERVOIR

Removing

Remove plenum chamber cover Removal and Installation .

Disconnect electrical connector from brake fluid level warning switch -F34-.

Remove brake fluid reservoir cover over brake fluid reservoir BRAKE FLUID RESERVOIR COVER .

To protect against escaping brake fluid, place enough lint-free cloths in the area below the master brake cylinder.

Extract as much brake fluid as possible from the brake fluid reservoir with the brake filler bleeder unit VAS 5234 and adapter VAS 5234/1.

With manual transmissions, remove the clutch hydraulic line -5- from the brake fluid reservoir and seal it.

Pull lower locking pin out of the brake fluid reservoir.

Remove brake fluid reservoir from the brake master cylinder.

Installing

Remove protective cap on new brake fluid reservoir just before filling it.

Coat plugs on brake fluid reservoir with brake fluid.

Insert brake fluid reservoir in the sealing plugs in the brake master cylinder.

Push lower locking pin through brake fluid reservoir.

Connect electrical connector from brake fluid level warning switch -F34-.

With manual transmission, connect the clutch hydraulic line -5- to the brake fluid reservoir.

Fill brake fluid up to marking.

Bleed brake system BRAKE SYSTEM, BLEEDING .

With manual transmissions, bleed the clutch .

Install brake fluid reservoir cover over the brake fluid reservoir.

Note. The brake fluid reservoir cover is not installed on all vehicle models.

Install plenum chamber cover Removal and Installation .

BRAKE MASTER CYLINDER

Removing

Special tools and workshop equipment required

1. Torque Wrench V.A.G 1331
2. Adapter VAS 5234/1
3. Brake filler/bleeder unit VAS 5234
4. Sealing plugs repair kit, Part no. 1H0 698 311 A

Removing

Remove plenum chamber cover Removal and Installation .

Remove engine cover.

Remove tower brace Removal and Installation .

Remove plenum chamber bulkhead Removal and Installation .

To protect against escaping brake fluid, place enough lint-free cloths in the area below the master brake cylinder.

Extract as much brake fluid as possible from the brake fluid reservoir with the brake filler /bleeder unit VAS 5234.

Remove brake fluid reservoir BRAKE FLUID RESERVOIR .

Disconnect brake lines -2- at brake master cylinder and seal brake lines with sealing plugs from repair kit.

Scheme 177

Remove brake master cylinder mounting nuts -3-.

Remove brake master cylinder from brake booster.

Remove brake master cylinder from vehicle.

Installing

Installation is in reverse order of removal.

Use new nuts.

Replace sealing ring between brake master cylinder and brake booster.

When replacing brake master cylinder, ensure pressure rod in brake booster is seated correctly.

Press brake pedal down slightly. This makes it easier to guide the push rod into the brake master cylinder.

Install new nuts -3- and tighten. Note torque.

Install brake lines -2- on brake master cylinder. Note torque.

Install brake fluid reservoir -1- BRAKE FLUID RESERVOIR .

With manual transmissions, insert the clutch hydraulic line -5- into the brake fluid reservoir.

Fill brake fluid up to the marking.

Bleed brake system BRAKE SYSTEM, BLEEDING .

With manual transmissions, bleed the clutch .

Install plenum chamber bulkhead Removal and Installation .

Install tower brace Removal and Installation .

Install engine cover.

Install plenum chamber cover Removal and Installation .

Perform ESP driving and system test.

BRAKE BOOSTER

Removing

Special tools and workshop equipment required

1. Torque Wrench V.A.G 1331
2. Adapter VAS 5234/1
3. Brake filler bleeder unit VAS 5234
4. Sealing plugs repair kit, Part no. 1H0 698 311 A

Switch engine off.

Press brake pedal until there is no more brake assistance - "pump brake booster empty". The brake pedal becomes hard.

Remove driver side storage compartment -1 to 3-.

Scheme 178

Disconnect electrical connector to the footwell vent -C-.

Scheme 179

Remove footwell vents -A-B-.

Remove brake lamp sensor BRAKE LAMP SENSOR .

Disconnect brake pedal from brake booster BRAKE PEDAL AND BRAKE BOOSTER, DISCONNECTING AND CONNECTING .

Remove engine cover.

Remove plenum chamber cover Removal and Installation .

Remove tower brace Removal and Installation .

Remove plenum chamber bulkhead Removal and Installation .

Remove brake fluid reservoir BRAKE FLUID RESERVOIR .

Remove brake master cylinder at the nuts -3- BRAKE MASTER CYLINDER .

Remove brake master cylinder from vehicle.

Place brake master cylinder so no brake fluid can drain out.

Remove vacuum line -3- from brake booster.

Scheme 180

Remove bolts mounting brake booster -1- to mounting bracket.

Remove brake booster from the vehicle.

Installing

Insert brake booster in the vehicle.

Make sure seal is seated correctly.

Install bolts -1- from brake booster to the mounting bracket and tighten them.

Press vacuum line -3- into brake booster.

Install brake master cylinder -15- BRAKE MASTER CYLINDER .

Install brake fluid reservoir -1- BRAKE FLUID RESERVOIR .

With manual transmissions, insert clutch hydraulic line -5- into brake fluid reservoir.

Fill brake fluid up to the marking.

Bleed brake system BRAKE SYSTEM, BLEEDING .

With manual transmissions, bleed the clutch .

Install plenum chamber bulkhead Removal and Installation .

Install tower brace Removal and Installation .

Install engine cover.

Install plenum chamber cover Removal and Installation .

Brake Pedal and Brake Booster, Connecting

Hold ball head of push rod in front of mounting and push brake pedal in direction of brake booster, so the ball head locates audibly.

Install brake lamp sensor BRAKE LAMP SENSOR .

Install footwell vents -A- and -B-.

Tighten footwell vent screw -A-.

Connect connector -C-.

Install driver side storage compartment -1 to 3-.

VACUUM PUMP, TURBO FSI 4-CYLINDER

Before removing the vacuum pump, the fuel high pressure pump must be removed Removal and Installation

The plenum chamber bulkhead does not have to be removed.

Removing

The vacuum pump is installed in the engine compartment facing the rear -arrow-.

Scheme 181

Remove engine covers carefully from the retaining pins, one after another.

Scheme 182

The vacuum pump is installed in the engine compartment on the right side facing the rear.

Disconnect fuel high pressure pump connector -1-.

Remove electric line from bracket -arrow-.

Scheme 183

Remove fuel high pressure pump -2- Removal and Installation .

Loosen ignition coil strip on the bracket.

Disconnect ignition coil connectors -arrow-.

Scheme 184

Carefully push ignition coil strip to side.

Disconnect wires on high pressure pump and on the vacuum pump and push them to the side.

Disconnect vacuum hose at the hose clamp to the vacuum pump.

Remove all the bolts on the vacuum pump sealing flange -arrows-.

Scheme 185

Note. Do not disconnect the vacuum hose from the vacuum line on the plenum chamber bulkhead -2-.

Remove vacuum pump from the mount.

Installing

Note. Replace the seal.

Make sure the seal is correctly installed.

Position vacuum pump tappet so it engages in the groove on the camshaft when vacuum pump is installed.

Make sure the seal is seated correctly.

Install and tighten all the bolts -arrows- on the vacuum pump sealing flange. Refer to item 1

Push new hose clamps over vacuum hose.

Push vacuum hose over connection on the vacuum pump.

Compress hose clamp on vacuum pump connections with pliers.

Connect wires to high pressure pump and to the vacuum pump.

Connect ignition coil connectors -arrow-.

Install ignition coil strip.

Install fuel high pressure pump Removal and Installation .

Install engine cover.

VACUUM PUMP, FSI V6

The vacuum pump is installed in the engine compartment at the front and on the left side in the driving direction.

Removing

Remove engine covers carefully from retaining pins, one after another.

Scheme 186

Loosens hose clamp on the vacuum hose.

Remove vacuum hose form vacuum pump.

Remove all bolts on the vacuum pump sealing flange.

Remove vacuum pump from the mount.

Installing

Note. Replace the seal.

Make sure the seal is correctly installed.

Position vacuum pump tappet so it engages in the groove on the camshaft when vacuum pump is installed.

Insert vacuum pump.

Make sure seal is seated correctly.

Install and tighten all bolts on the vacuum pump sealing flange. VACUUM PUMP ASSEMBLY OVERVIEW ) Bolt

Push new hose clamps over the vacuum hose.

Push vacuum hose over the connection on the vacuum pump.

Compress hose clamp on the vacuum pump connections with pliers.

Carefully install engine covers into retaining bolts one after the other.

VACUUM PUMP

The construction of the vacuum pump V192 depends on the engine.

The brake system vacuum pump -V192- is switched on by the engine control module depending on the intake line pressure.

Vacuum pump is not intended to be serviced. In case of complaints, determine cause with help of function or seal test. If there is a malfunction, replace electrical vacuum pump.

Removing

Note. The electrical vacuum pump is located in the engine compartment on the right side in front of the plenum chamber bulkhead.

Remove engine cover.

Disconnect electrical connector -1-.

Scheme 187

Loosen clamp on vacuum hose using suitable pliers.

Disconnect vacuum hose from the vacuum pump.

Press right and lift clips -arrow- out of the bracket by hand.

Scheme 188

Remove electrical vacuum pump upward while holding the rubber buffer securely.

Scheme 189

Note. When removing the vacuum pump V192, make sure the lower rubber buffer does not fall into the engine compartment.

Installing

Installation is in reverse order of removal.

Note. Use new clamps when installing the vacuum line.

VACUUM PUMP BRACKET

Note. To remove the bracket, the vacuum pump must first be removed from the bracket.

Removing

Remove engine cover.

Remove vacuum pump VACUUM PUMP .

Remove two nuts -6- on bracket.

Remove bracket from vehicle.

Installing

Installation is in reverse sequence.

BRAKE BOOSTER PRESSURE SENSOR

Removing

Remove plenum chamber cover Removal and Installation .

Note. The brake booster pressure sensor -G294- is located in the plenum chamber near the brake booster.

Disconnect electrical connector -1-.

Remove pressure sensor in direction of -arrow-.

Scheme 190

Note. The pressure sensor is secured with clips.

Release clips with pliers -1-.

Scheme 191

Carefully pry Brake Booster Pressure Sensor -G294- off.

Installing

Installation is in reverse order of removal.

CHECK VALVE

Removing

Remove vacuum hose on left and right of the check valve -4-.

Remove check valve from vehicle.

Installing

Installation is in reverse sequence. Observe the following when doing so

Valve must allow air to flow in direction of arrow.

The arrow indicates the direction of the vacuum pump.

Scheme 192

Special tools and workshop equipment required

1. Torque Wrench V.A.G 1331
2. Torque Wrench V.A.G 1332
3. Piston Resetting Tool T10145
4. Disassembly wedge 3409
5. Vehicle Diagnostic, Test And Information System VAS 5051B

Special tools and workshop equipment required

Scheme 193

Scheme 194

1. Brake pressure gauge 0-250 bar V.A.G 1310A
2. Brake filler bleeder unit VAS 5234
3. Adapter VAS 5234/1

See also:
• BRAKE FLUID
• Removal and Installation
• BRAKE CALIPER WITH FRONT BRAKE CARRIER
• BRAKE PEDAL, WITH MANUAL TRANSMISSION
• BRAKE PEDAL, WITH AUTOMATIC TRANSMISSION
• BRAKE LAMP SENSOR
• Removal and Installation
• BRAKE PEDAL AND BRAKE BOOSTER, DISCONNECTING AND CONNECTING
• Removal and Installation
• BUSHING AND GUIDE PINS, REPLACING
• PROTECTIVE CAP AND GUIDE PINS, REPLACING
• REAR BRAKE CALIPER PISTON
• REAR BRAKES GUIDE PINS AND PROTECTIVE CAPS, REPLACING
• BRAKE FLUID RESERVOIR
• BRAKE FLUID RESERVOIR COVER
• BRAKE BOOSTER
• BRAKE MASTER CYLINDER
• VACUUM PUMP
• BRAKE SYSTEM VACUUM PUMP, CHECKING
• CHECK VALVE, CHECKING
• VACUUM PUMP BRACKET
• BRAKE SYSTEM, BLEEDING