Master cylinder, removing and installing

WARNING: This page is about a different car, the 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 other items required

Fig 1: Identifying Hose Clamps 3094

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3094 Hose clamp

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

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VAG 1922 Pliers

Removing

Pull off gasket on plenum chamber in direction of arrow.

Fig 3: Removing Cover Over Plenum Chamber

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Remove cover -1- on top of plenum chamber.
First check if a coded radio is installed. In this case obtain anti-theft code.

See Caution for disconnecting Telematics battery. Refer to Clutch mechanism components (on chassis)

Disconnect battery Ground strap with ignition switched off.

Fig 4: Removing Securing Clips And Cowl

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Pry off two covers -3- with a screwdriver.
Remove nuts -4- and two wiper arms -2-.
Pull off clips -1- and remove cowl panel grille -5-.

Remove electronics box in plenum chamber as follows:

Fig 5: Electronics Box Sealing Cover

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Remove bolts (arrows) and take off cover lid.

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

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Carefully pry off mount bar with screwdriver (arrow).

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

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Loosen connector locks (arrows) and unplug connectors -1- and -2- from engine control module.

Fig 8: Connector At Connector Rail And Wire

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Remove connectors -2- from connector strip.
Disconnect electrical connection -1-.

Fig 9: Locating Auxiliary Relay Carrier Catches

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Release locks (arrows) and pull auxiliary relay carrier in electronics box upward and off.
Pull engine wiring harness together with grommet out of recess in electronics box.

Fig 10: Electronics Box Nuts

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

NOTE:

During the following steps make sure that brake fluid does not escape into plenum chamber or onto transmission below. If it does, clean affected area thoroughly.
When working in footwell, cover carpet with cloths to protect it from brake fluid spillage.

Fig 11: Identifying Brake Fluid Reservoir Return Hose Grommet

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Disconnect supply hose -A- to brake fluid reservoir with special tool 3094, disconnect from master cylinder and seal with plug.
On bulkhead remove grommet above connecting tube for supply hose.
Pry out securing clip -C- with screwdriver and then pull tube -B- out slightly.

Fig 12: Location Of Brake Fluid Reservoir Dowel Bolt

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Remove bolt for brake fluid reservoir -1- and unplug connector for monitoring fluid level by pulling downward.

NOTE: Do not remove brake fluid reservoir.

NOTE:

Brake fluid reservoir not shown for purpose of clearer illustration.
To remove the top TORX bolt; swivel brake fluid reservoir sideways slightly.

Fig 13: Location Of Brake Servo Securing Bolts

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Remove two TORX bolts (arrows).
Remove vacuum tube to brake booster -1-.
Remove driver's storage compartment.

Refer to

68 - INTERIOR EQUIPMENT
68 - INTERIOR EQUIPMENT for Cabriolet

Fig 14: Brake Pedal At Brake Servo

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Separate brake pedal from brake booster.

Refer to 47 - BRAKES - HYDRAULIC 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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Separate steering column from steering box (arrow A).

Refer to 48 - STEERING

Disconnect connectors from clutch pedal switch -1-, brake pedal switch -2- and accelerator pedal module -3-.
Remove bolt for mounting bracket (arrow B) and remove pedal cluster assembly.

Release master cylinder operating rod from clutch pedal as follows:

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

NOTE:

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

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When releasing make sure clutch pedal does not bounce against clutch pedal switch mount (arrow). Otherwise the mount might break.
In order to assure sufficiently secure fitting of clutch pedal switch. Refer to Pedal cluster, assembly overview Item 6- as well as Clutch pedal starter interlock switch -F194-. Refer to Pedal cluster, assembly overview Item 14- in pedal cluster, these switches must not be installed more than once.

Insert pliers VAG 1922 into recesses in clutch pedal, compress mount (arrows) and separate clutch pedal from master cylinder.

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

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Remove securing clip -1- and clutch pedal -2-.
Remove bolts -3- and master cylinder -4-.

Installing

Install in reverse order, paying attention to 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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Insert mount -1- in clutch pedal.
Push clutch pedal in direction of arrow to lock into place, while making sure mount -1- is properly secured in clutch pedal.
Installing over-center spring. Refer to Over-center spring, removing and installing .

For the next step a second technician is required.

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

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Insert pedal cluster assembly and tighten bolt -1- hand-tight. Simultaneously, second technician feeds tube from plenum chamber side into master cylinder.

Fig 21: Location Of Brake Servo Securing Bolts

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Tighten brake booster bolts (arrows) to 25 Nm.

Fig 22: Installing Rubber Grommet And After-Run Hose

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Push in securing clip -C- as far as it will go.
Insert tube -B- in master cylinder until it clicks into position.
Install grommet -D- over connecting tube/supply hose -A- and into bulkhead.
Push on supply hose -A- to brake fluid reservoir as far as it will go.

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

Fig 23: Locating Connectors

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Tighten hex socket-head bolt (arrow B) which secures pedal cluster to instrument panel carrier to 25 Nm.
Attach connectors -1-, -2- and -3-.
Connect brake pedal to brake booster.

Refer to 47 - BRAKES - HYDRAULIC COMPONENTS

Attach steering column to steering box (arrow A).

Refer to 48 - STEERING

Install driver's storage compartment:

Refer to

68 - INTERIOR EQUIPMENT
68 - INTERIOR EQUIPMENT for Cabriolet

Bleed clutch system. Refer to Clutch system, bleeding .

Fig 24: Electronics Box Nuts

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Insert electronics box and tighten nuts (arrows) to 4 Nm.
Route engine wiring harness and attach connection in connector station.
Install engine control module plus auxiliary relay carrier and auxiliary fuse holder, if installed.

Refer to 97 WIRING r.

Push on cover lid by hand and tighten bolts diagonally - 4 Nm.

See Caution for connecting Telematics battery. Refer to Clutch mechanism components (on chassis)

NOTE: If the battery is reconnected remember to check and activate vehicle equipment (radio, clock, convenience electronics etc.).

Refer to

01 - MAINTENANCE
01 - MAINTENANCE for Cabriolet