Operating instructions

1. Check TDC position of piston in cylinder A1:
• If the rocker arms are unloaded on cylinder A1, the piston is in firing TDC.
• If the rocker arms are under load on cylinder A1, the piston is in overlap TDC.
2. Check valve clearance with cold engine:
• Inlet valves (long rocker arm) = 0.2 mm
• Exhaust valves (short rocker arm) = 0.5 mm
3. Check all valve clearances in two crankshaft positions (firing TDC and overlap TDC of cylinder A1) as
per diagram.
4. Use feeler gauge to determine the distance between valve bridge and rocker arm.
5. If the deviation from the set value exceeds 0.1 mm, adjust valve clearance.
Adjusting valve clearance
1. Release locknut (1).
2. Insert feeler gauge between valve bridge
and rocker arm.
3. Turn adjusting screw (2) with Allen key until
appropriate valve clearance is set.
4. Feeler gauge must just pass through the
gap.
5. Tighten locknut (1) to 90 +9 Nm, holding
adjusting screw (2) firmly.
6. Replace or rectify adjusting screws and/or
locknuts which do not move freely.
7. Check valve clearance.
Final steps
1. Remove barring device (→ Page 112).
2. Install cylinder head cover (→ Page 127).
126 | Task Description | M015412/03E 2012-02
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