Timing chain replacement: BMW 3.0 (N53B25A, N53B30A)

🧭 Before you start

Fits: platform codes 325I, |, XI, 330I, 523I, 525I, 530I, 630I

• Timing position: the crankshaft or camshaft is set and locked during this job
• Special tools named: locking tool, locking pin

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• If the timing chain is to be re-used, mark the running direction before removal

🔧 Engine codes this applies to

📋 Procedure

Preparation and removal

1. Chain guide:
2. Remove the fan cowling
3. If the timing chain is to be re-used, mark the running direction before removal
4. Crankshaft locking tool:
5. Fit the special tool

6. Remove the injectors
7. Tighten the crankshaft gearwheel bolt
8. Use new bolt(s)
9. Remove the spark plugs
10. Remove the chain tensioner piston
11. Remove the engine lower cover
12. Release the ancillary drive belt tension
13. Cylinder head cover
14. Use new bolt(s)
15. Note: Do not remove
16. Fit the special tools
17. Tighten the special tool
18. Remove the special tools
19. Fit the special tools
20. Tighten the special tool
21. Remove and discard the crankshaft oil seal
22. Remove the ancillary drive belt tensioner
23. Remove the access plug
24. Fit the crankshaft TDC locking pin
25. Fit the camshaft locking tools
26. Remove the inlet camshaft timing adjuster
27. Remove the exhaust camshaft timing adjuster
28. Lock the flywheel
29. Use the special tools
30. Remove the crankshaft locking pin
31. Remove the crankshaft gearwheel centre bolt

Installation and checks

32. Refit the guide pins
33. Refit the access plugs
34. Refit the inlet camshaft adjuster
35. Tighten the camshaft gearwheel bolts lightly until there is no play
36. Fit the crankshaft TDC locking pin
37. Fit the camshaft alignment tool
38. Align the camshaft gearwheel marks as shown
39. Pre-tension the timing chain
40. Use the special tools
41. Tighten the camshaft gearwheel bolts
42. Use new bolt(s)
43. Stage 1:
44. Stage 2:
45. Refit the chain tensioner piston
46. Note: Install a sealing ring
47. Remove the timing chain guide bolts from the cylinder head
48. Turn the engine 2 rotations by hand
49. Check the timing again
50. Refit the ancillary drive belt tensioner
51. Fit the special tools
52. Apply grease
53. Fit the crankshaft seal over the special tool
54. Note: The seal should be aligned with the timing cover
55. Refit the crankshaft front radial seal
56. Use the special tool
57. Apply sealant
58. Refit the crankshaft pulley
59. Fit the ancillary drive belt
60. Tension the belt
61. Refit the engine lower cover
62. Refit the spark plugs
63. Refit the cylinder head cover
64. Use new bolt(s)
65. Refit the air duct
66. Refit the strut brace connecting the shock absorbers
67. Refit the injectors
68. Reconnect the injection wiring
69. Refit and connect the ignition coils
70. Refit the engine upper cover
71. Refit the fan cowling
72. Reconnect the battery earth cable

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