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MTU — Valve clearance - Check and adjustment

Adjustments · Valve drive

From a MTU operator's manual covering: 12 V 4000 G23, 12 V 4000 G43, 12 V 4000 G63, 12 V 4000 G83, 12 V 4000 Gx3, 12/16V 4000 Gx3, 12V 4000 G23, 12V4000 G23, 16 V 4000 G23, 16 V 4000 G43, 16 V 4000 G63, 16 V 4000 G83. Check it applies to your exact model before use.

Applies to: MTU 12 V 4000 G23, MTU 12 V 4000 G43, MTU 12 V 4000 G63, MTU 12 V 4000 G83, MTU 12 V 4000 Gx3, MTU 12V4000 G23, MTU 16 V 4000 G23, MTU 16 V 4000 G43, MTU 16 V 4000 G63, MTU 16 V 4000 G83, MTU 12V/16V 4000 Gx3 engine

Procedure

  1. Remove cylinder head cover.
  2. Install barring tool.
  3. Rotate crankshaft with barring tool until marking OT-A1 and pointer are aligned.
  4. Check TDC position of piston in cylinder A1 (unloaded rocker arms = firing TDC; loaded = overlap TDC).
  5. Check valve clearance with cold engine: inlet valves 0.2 mm, exhaust valves 0.5 mm.
  6. Check all valve clearances at two crankshaft positions as per diagram.
  7. Use feeler gauge between valve bridge and rocker arm.
  8. If deviation exceeds 0.1 mm, adjust valve clearance.
  9. Release locknut; insert feeler gauge between valve bridge and rocker arm.
  10. Set adjusting screw with Allen key so specified clearance is provided; feeler gauge must just pass through.
  11. Tighten locknut to 90 ±9 Nm holding adjusting screw firm.
  12. Replace or rectify adjusting screws/locknuts which do not move freely.
  13. Check valve clearance.
  14. Remove barring tool and install cylinder head cover.

Tools required

  • Feeler gauge Y20010128 Amazon
  • Torque wrench 60-320 Nm F30047446 Amazon
  • Ring socket, 24 mm F30039526 Amazon

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Inlet valve clearance 0.2 mm (cold)
  • Exhaust valve clearance 0.5 mm (cold)
  • Locknut 90 ±9 Nm
  • Engine coolant temperature max. 40 °C

Full service-parts list: MTU 12 V 4000 G23 →, MTU 12 V 4000 G43 →, MTU 12 V 4000 G63 →, MTU 12 V 4000 G83 →, MTU 12 V 4000 Gx3 →, MTU 12V4000 G23 →, MTU 16 V 4000 G23 →, MTU 16 V 4000 G63 →

Source: MTU operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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