Timing chain replacement: Mercedes-Benz eng. (112.951, 112.976)

🧭 Before you start

Fits: platform codes VIANO, 3.0, |, 3.2, 3.5, VITO, 119, 122, 123

• Timing position: the crankshaft or camshaft is set and locked during this job

Don't miss

• Never turn the engine in the direction opposite to that of normal operation
• Mark the timing chain and camshaft gearwheels to each other with paint
• Do not turn the engine anti-clockwise
• If the special tools do not fit

🔧 Engine codes this applies to

📋 Procedure

Preparation and removal

1. Unless otherwise advised by the manufacturer, the following procedures are recommended:
2. Timing chain assembly links:
3. Never turn the engine in the direction opposite to that of normal operation
4. Disconnect the battery earth cable
5. Remove the air inlet hose

6. Chain tensioner
7. Mark the timing chain and camshaft gearwheels to each other with paint
8. If necessary
9. Use the special tools
10. Left cylinder head:
11. Disconnect the vacuum hose from the valve cover
12. Disconnect the crankcase breather hose from the valve cover
13. Remove the cylinder head cover
14. Right cylinder head:
15. Disconnect the vacuum hose from the valve cover
16. Remove the dipstick tube
17. Remove the cylinder head cover
18. Remove the cooling fan
19. Lock the camshafts
20. Remove the alternator
21. Fit the camshaft locking tools
22. If the special tools do not fit
23. Remove the camshaft gearwheels
24. During the removal of the camshaft gearwheel, the timing chain should remain in position
25. Turn the camshafts until the locking tools fit
26. Use a wrench
27. Left cylinder head:
28. Remove the camshaft bearing bridge

Installation and checks

29. Connect the ends of the new chain
30. Fit the timing chain and camshaft gearwheel together
31. Tighten the camshaft gearwheel
32. Stage 2:
33. Check the camshaft timing marks
34. Note: Do not turn the engine anti-clockwise
35. Fit the timing chain and camshaft gearwheel together
36. Fit the locating bush onto the camshaft
37. Fit the timing chain onto the camshaft gearwheel
38. Fit the timing chain and camshaft gearwheel together
39. Tighten the camshaft gearwheels
40. Secure the chain
41. Use the special tool
42. Check the timing marks again
43. Remove the camshaft locking tools
44. Right cylinder head:
45. Remove the locating bush from the camshaft
46. Refit the camshaft bearing bridge
47. Renew the bolt(s)
48. Tighten the bolts
49. In the order shown
50. Renew the O-ring
51. Refit the Hall sensor(s)
52. Renew the seal
53. Fit the chain tensioner
54. Refit the alternator
55. Fit the drive belt
56. Refit the viscous fan
57. Right cylinder head:
58. Refit the cylinder head cover
59. Renew the gasket
60. Tighten the bolts
61. Check the gasket position
62. Refit the dipstick tube
63. Reconnect the vacuum hose
64. Left cylinder head:
65. Refit the cylinder head cover
66. Renew the gasket
67. Tighten the bolts
68. Check the gasket position
69. Reconnect the crankcase breather hose
70. Reconnect the vacuum hose
71. Refit the automatic transmission dipstick tube
72. Check the fluid level
73. If necessary
74. Reconnect the air-conditioning line(s)
75. Fit the air-conditioning compressor hose
76. Refill the air-conditioning system
77. Refit the spark plugs
78. Refit the spark plug cables
79. Refit the ignition coil(s)
80. Refit the air filter housing
81. Refit the air inlet hose
82. Refit the engine upper cover(s)
83. Reconnect the battery earth cable

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