Timing chain replacement: BMW M51

🧭 Before you start

Fits: platform codes 525TD, |, 525TDS

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

Don't miss

• Ensure the valves make no contact with the pistons

📋 Procedure

Preparation and removal

1. Before disconnecting the battery cable, check the audio system security code
2. Stage 1:
3. Hold the injection pump in this position
4. Disconnect the tie rods
5. Disconnect the power steering hose

6. Disconnect the power steering line
7. Remove the steering column universal joint
8. Remove the engine cover
9. Remove the locking pin from the chain tensioner
10. Fit the tool as shown
11. Slowly lift the engine
12. Place the jack under the front axle subframe
13. Remove the anti-roll bar
14. Disconnect the lower arm ball joints
15. Check the dowel pin(s) for damage
16. Turn the crankshaft to 30° BTDC for cylinder 1
17. Note: Ensure the valves make no contact with the pistons
18. Disconnect the suspension lower wishbones from the wheel bearing housings
19. Remove the heat shield(s)
20. Disconnect the steering box from the front subframe
21. Remove the front axle body bolts
22. Turn the crankshaft to TDC for cylinder 1
23. Fit the crankshaft locking tool
24. Remove the fan and coupling
25. Remove the injection lines
26. Drain the coolant
27. Disconnect the coolant hoses from the cylinder head
28. Remove the tensioner bracket
29. Remove the cylinder head cover
30. Remove the vacuum pump
31. Remove the tensioner locking bolt
32. Remove the timing chain guide bolts from the cylinder head
33. Remove the fuel return hoses from the injectors
34. Remove the cylinder head
35. Remove the coolant pump pulley
36. Fit the crankshaft locking tool
37. Remove the oil filter cartridge
38. Disconnect the oil lines from the engine block
39. Disconnect the power steering fluid reservoir
40. Remove the coolant expansion tank and place it aside
41. Remove the ancillary drive belt tensioner
42. If necessary
43. Remove the bearing pin from the timing cover
44. Use the special tool
45. Remove the crankshaft front radial seal
46. Remove the lower timing cover
47. Lock the chain tensioner with a locking pin
48. Lift the engine slightly
49. Set the injection pump timing
50. Remove the lower engine cover
51. Remove the drain plug
52. Fit a dial gauge
53. Use the special tool
54. Turn the crankshaft clockwise
55. Turn the crankshaft to TDC until the micrometer indicates the lowest point
56. Set the dial gauge to zero
57. Remove the oil filler cap
58. Note: The cams for cylinder 1 should point straight up
59. Remove the access plug
60. Turn the crankshaft until the locking pin fits
61. Read the dial gauge value
62. Loosen the injection pump bolt slightly

Installation and checks

63. Fit the timing chains
64. Stage 4:
65. Injection pump gearwheel:
66. Tighten the injection pump gearwheel
67. Crankshaft front radial seal fitting tool:
68. Refit the crankshaft front radial seal
69. Renew the bolt(s)
70. Measure the distance:
71. Reconnect the fuel return line
72. Set the camshaft position
73. Fit the camshaft locking tool
74. Fit the camshaft gearwheel
75. Fit the special tool
76. Apply pressure to the tensioner
77. Tighten the camshaft gearwheel bolt
78. Refit the ancillary drive belt tensioner
79. Refit the alternator bracket
80. Refit the alternator
81. Refit the coolant expansion tank
82. Refit the EGR valve
83. Reconnect the air pressure sensor
84. Refit the oil filter cartridge
85. Fit the coolant pump
86. Renew the O-ring
87. Refit the crankshaft hub
88. Apply pressure to the tensioner
89. Stage 1:
90. Stage 2:
91. Fit the crankshaft pulley
92. Refit the vacuum pump
93. In the reverse order to that shown
94. Fit the alternator drive belt
95. Refit the EGR hose
96. Reconnect the glow plugs
97. Reconnect the coolant hoses
98. Remove the crankshaft locking tool
99. Refit the inlet manifold
100. Refit the dipstick tube
101. Refit the oil level plug
102. Fit the oil lines
103. Refit the subframe
104. Fit the subframe bolts
105. Use the special tools
106. Refit the lower suspension arms
107. Check the marks
108. Remove the jack
109. Reconnect the power steering lines to the engine mount
110. Remove the engine support tool
111. Refit the air filter housing
112. Refit the engine cover
113. Refit the steering column universal joint
114. Reconnect the lines
115. Refit the tie rod end nut
116. Refit the steering wheel in the straight-ahead position
117. Refit the front wheels
118. Remove the crankshaft locking tool
119. Refit the lower splash guard
120. Refill the power steering system
121. Refill the cooling system
122. Refill the engine oil
123. Turn the injection pump until the dial gauge indicates the correct value
124. Tighten the injection pump bolts
125. Refit the engine lower cover
126. Reconnect the battery earth cable

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