Removing and installing brake master cylinder, LHD — VW

🧭 Before you start

Remove the engine cover panel, battery, air filter, intake hose and battery tray, sealing the openings. Lay cloths down, draw off brake fluid, clamp and detach the clutch supply hose, unplug the level warning and brake light switch connectors and lift off the reservoir. Disconnect and plug the brake lines, undo the nuts and remove the cylinder. Fit the new one with the plunger rod seated, reinstall the battery and bleed the brake system.

Fits: platform code AJ5

• Opens: brake fluid

Don't miss

• Never let brake fluid contact oil, petrol or cleaning agents; mineral oils damage the seals.
• Drawn-off brake fluid is not reused; dispose of it under local environmental rules.
• Plug the brake lines immediately after disconnecting to keep dirt and moisture out.
• Check the booster plunger rod is properly positioned in the master cylinder before tightening the nuts.
• The system must be fully bled afterwards, including the clutch circuit if its supply hose was disturbed.

Written for this job from the workshop steps below · TorqFix editorial.

📋 Procedure

1. Remove engine cover panel 10Engine cover; Removing and installing engine cover panel.
2. Remove battery Electrical system27Removing and installing batteries.
3. Remove air filter 24Air filter; Assembly overview - air filter housing.
4. If necessary, remove intake hose (2)24Air filter; Assembly overview - air filter housing.
5. To do this, loosen clamps (1).

6. Seal openings with engine bung setVAS 6122.
7. Remove air filter 23Air filter; Assembly overview - air filter housing.
8. If necessary, remove intake hose (2)23Air filter; Assembly overview - air filter housing.
9. To do this, loosen clamps (1).
10. Seal openings with engine bung setVAS 6122.
11. Remove battery tray Electrical system27Battery; Removing and installing battery tray.
12. Place sufficient lint-free cloths in area of engine and gearbox.
13. Draw off as much brake fluid as possible from brake fluid reservoir using brake filling and bleeding equipmentVAS 5234.
14. ⚠ Do not under any circumstances allow brake fluid to come into contact with fluids that contain mineral oils (e.g. oil, petrol, cleaning agents). Mineral oils damage the plugs and seals in the brake system.Brake fluid is poisonous and must on no account be sucked out by mouth through a hose. Because of its caustic properties it must also not come into contact with paintwork.Do not reuse drawn off brake fluid.Always observe the relevant environmental regulations for disposal. — Clamp off supply hose (B) for clutch master cylinder with hose clamps, up to Ø 25 mm3094.
15. Detach supply hose (B) for clutch master cylinder.
16. Release connector (A) from brake fluid level warning contact F34(2) and pull off connector.
17. Release connector (C) from brake light switchF and pull it off.
18. Remove brake fluid reservoir .
19. Disconnect brake lines (1) from brake master cylinder and seal brake lines using sealing plugs1H0 698 311 A.
20. Undo nuts (2) on brake master cylinder.
21. Remove heat shield (if installed).
22. Carefully remove brake master cylinder from brake booster.
23. When joining brake master cylinder to brake booster, make sure plunger rod is properly positioned in brake master cylinder.
24. Install and connect battery Electrical system27.
25. Bleed brake system .

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