Valve clearance adjustment, code 11.49022-0253-1.A, is another vital process in maintaining the MAN L21/31 engine’s reliability. Correct valve clearance guarantees that valves open and close at the right intervals without excessive play or tightness. If neglected, improper clearance can lead to reduced performance, overheating, or even mechanical failure. Routine valve clearance adjustments are essential for ensuring smooth operation, optimal power output, and long-term durability of the engine.