Master cylinder, removing and installing

WARNING: This page is about a different car, the 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Special tools, testers and auxiliary equipment required

Fig 1: Identifying Hose Clamps 3094

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3094 Hose clip

Fig 2: Identifying Spark Plug Connector Pliers V.A.G 1922

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V.A.G 1922 Pliers

Removing

WARNING:

Observe safety precautions when disconnecting the battery.

Refer to

See Caution before beginning repairs on the electrical system. Refer to Clutch mechanism, servicing

With the ignition switched off disconnect the battery Ground strap.
Pull the rubber gasket off plenum chamber in direction of arrow.

Fig 3: Identifying Plenum Chamber Cover & Removing Rubber Seal

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Remove cover -1- above plenum chamber.

Fig 4: Removing Securing Clips And Cowl

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Lever off both trim caps -3- with a screwdriver.
Unscrew nuts -4- and remove both wiper arms -2-.
Pull off clips -1- and remove cowl grille -5-.

Remove the electronics box from the plenum chamber as follows:

Fig 5: Removing Screws And Cover From E-Box In Plenum Chamber

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Unscrew the bolts -arrows- and pull off the sealing cap.

Fig 6: Using Screwdriver To Remove Retainer Bar And Engine Control Module (ECM) J623

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Carefully lever off the retainer bar with a screwdriver -arrow-.

Fig 7: Releasing Connector Latches And Pulling Off Connectors On Engine Control Module

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Release the connector catches -arrows- and detach connectors -1- and -2- of engine control unit.

Fig 8: Connector At Connector Rail And Wire

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Detach connectors -2- on connector console.
Unscrew the electrical wiring connection -1-.

Fig 9: Locating Auxiliary Relay Carrier Catches

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Release catch -arrow- and detach additional relay carrier in electronics box upward.
Pull engine wiring harness together with rubber grommet through opening in electronics box.

Fig 10: Electronics Box Nuts

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Remove nuts -arrows- and lift out electronics box -1-.

NOTE:

In the following steps make sure that no brake fluid escapes into the plenum chamber or onto the transmission below. If this does happen, clean the affected areas thoroughly.
When performing work in the footwell, put cloths on the carpet to protect it from possible brake fluid spills.

Fig 11: Identifying Brake Fluid Reservoir Return Hose Grommet

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Clamp supply hose -A- leading to brake fluid reservoir using special tool 3094. Pull hose off at master cylinder and plug it.
Remove rubber grommet from cross panel above connection pipe for supply hose.
Pry out retaining clip -C- with a screwdriver and then pull out pipe -B- slightly.

Fig 12: Location Of Brake Fluid Reservoir Dowel Bolt

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Unscrew bolt for brake fluid reservoir -1- and detach fluid level connector downward.

NOTE: The brake fluid reservoir is not removed.

NOTE:

For the sake of clarity, the brake fluid reservoir is not shown here.
To remove the upper Torx bolt, the brake fluid reservoir must be swivelled slightly to one side.

Fig 13: Location Of Brake Servo Securing Bolts

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Remove the two Torx bolts -arrows-.
Detach vacuum pipe from brake servo -1-.
Remove driver's side storage compartment.

Refer to

68 - INTERIOR EQUIPMENT
68 - INTERIOR EQUIPMENT for Cabriolet

Fig 14: Brake Pedal At Brake Servo

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Detach brake pedal from brake servo.

Refer to 46 - BRAKES - MECHANICAL COMPONENTS

Fig 15: Locating Steering Column At Steering Gear And Disconnecting Connector On Clutch Pedal Switch, Brake Pedal Switch And On Accelerator Pedal Module

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Detach steering column from steering box -arrow A-.

Refer to 48 - STEERING .

Detach connectors from clutch pedal switch -1-, brake pedal switch -2- and from accelerator pedal module -3-.
Unscrew retaining bolts for mounting bracket -arrow B- and remove the complete pedal cluster.

Separate master cylinder operating rod from clutch pedal as follows:

Removing over-center spring. Refer to Over center spring, removing and installing .

NOTE:

In order to assure sufficiently secure installations of Clutch Vacuum Vent Valve Switch -F36- -Item 6-: Refer to Pedal cluster assembly, overview and of Clutch Pedal Position (CPP) Switch -F194- -Item 14-: Refer to Pedal cluster assembly, overview (Interlock switch) in the pedal assembly, these switches must not be installed more than once.

Fig 16: Pressing Retainer Together And Detaching Clutch Pedal From Master Cylinder Using VAG 1922

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When releasing, make sure that the clutch pedal does not knock against the mount for the clutch pedal switch -arrow-. The mount could break off.

Position pliers VAG 1922 in the clutch pedal recesses, press the mount together -arrow- and detach clutch pedal from master cylinder.

Fig 17: Identifying Retaining Clip, Clutch Pedal, Bolts And Master Cylinder

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Release securing clip -1- and remove clutch pedal -2-.
Screw out bolts -3- and remove master cylinder -4-.

Installing

Installation is carried out in the reverse order, when doing this note the following:

Fig 18: Identifying Retaining Clip, Clutch Pedal, Bolts And Master Cylinder

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Insert master cylinder and tighten bolts -3- to 20 Nm.

Fig 19: Pushing Clutch Pedal To Lock Into Place, While Making Sure Mount Is Properly Secured In Clutch Pedal

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Install mount -1- in clutch pedal.
Press the clutch pedal in direction of arrow until it engages; ensure correct locking of the mount -1- in the clutch pedal.
Installing over-center spring. Refer to Over center spring, removing and installing .

A second mechanic is required for the next step.

Fig 20: Location Of Clutch Pedal Switch F36 And Pedal Assembly Securing Bolt

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Insert complete pedal cluster and tighten bolt -1- finger tight. The second mechanic should guide the pipe into the master cylinder starting from the plenum chamber.

Fig 21: Location Of Brake Servo Securing Bolts

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Tighten the retaining bolts for the brake servo -arrows- to 25 Nm.

Fig 22: Installing Rubber Grommet And After-Run Hose

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Press retaining clip -C- home.
Push pipe -B- into master cylinder until it audibly locks in place.
Insert rubber grommet -D- over connection pipe/supply hose -A- into the cross panel.
Slide supply hose -A- for the brake fluid reservoir on as far as its stop.

Remove special tool 3094.
Screw in securing bolt for brake fluid reservoir.

Fig 23: Locating Steering Column At Steering Gear And Disconnecting Connector On Clutch Pedal Switch, Brake Pedal Switch And On Accelerator Pedal Module

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Tighten the hex socket head bolt -arrow B- for securing pedal cluster to dash panel crossmember to 25 Nm.
Plug in connectors -1-, -2- and -3-.
Connect brake pedal to brake servo.

Refer to 46 - BRAKES - MECHANICAL COMPONENTS

Attach steering column to steering box -arrow A-.

Refer to 48 - STEERING

Install storage compartment for driver's side:

Refer to

68 - INTERIOR EQUIPMENT
68 - INTERIOR EQUIPMENT for Cabriolet

Bleed the clutch system. Refer to Clutch system, bleeding .

Fig 24: Electronics Box Nuts

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Insert the electronics box and tighten nuts -arrows- to 4 Nm.
Route the engine wiring harness and join the connector in the connector station.
Install the engine control unit and, if removed, also the auxiliary relay carrier and the auxiliary fuse box.

Refer to

97 WIRING
97 WIRING for Cabriolet

Press on sealing cap hand-tight and tighten bolts in diagonal sequence - 4 Nm.

See Caution for disconnecting Telematics battery. Refer to Clutch mechanism, servicing

Observe safety precautions after connecting the battery.

Refer to