The crankshaft, identified by code P51001-14, is the backbone of the MAN L21/31 engine’s power transmission system. Forged from high-strength steel, it converts the reciprocating motion of the pistons into rotational energy to drive the engine. The crankshaft must endure enormous stresses and maintain perfect alignment under continuous operation, making its durability and precision fundamental to overall engine performance and reliability.
The turning gear, code P51325-23, is an essential auxiliary device in the MAN L21/31 engine that allows safe, controlled rotation of the crankshaft during inspection, maintenance, and startup procedures. Powered by a 3 x 440V electric system, the turning gear ensures precise positioning of engine components, preventing damage and enabling thorough checks of pistons, valves, and bearings. Its reliability is critical for both operational safety and ease of service.
The nut K 27258 secures the fuel pressure valve in the Sulzer ZV40/48 and is a small but safety-critical fastener: it holds the valve body, maintains sealing compression on washers/O-rings, and resists loosening from vibration and pressure pulses. Typically made from high-strength, corrosion-resistant steel and fitted with the specified torque (and locking means where required), correct installation prevents leaks and pressure loss. Include this nut in routine inspections — replace if rounded, corroded or if preload is lost to ensure reliable fuel pressure control.
The fuel pressure line K 27251 denotes an individual high-pressure pipe section used in the ZV40/48 fuel system; it carries metered fuel under pressure from pump or distributor to the valve body. Manufactured to tight tolerances and from materials resistant to fuel, pressure and vibration, this single line is a critical flow path — even small nicks or deformation will compromise pressure and lead to leaks or spray. Technicians should check supports, fittings and protective sleeves during each service interval and replace the line if bending, corrosion or erosion is observed.
The complete fuel pressure line K 27250 is a ready-to-install assembly for the Sulzer ZV40/48 that includes the high-pressure tubing, end fittings, seals and any required brackets or flexible sections to connect the fuel pump or distributor to the injection or control valves. Built and routed to withstand the engine’s operating pressures and vibration, a complete line saves installation time and reduces leak risk because the components are matched and pressure-tested as an assembly. Regular inspection of the fittings, clamps and seals on the complete line is essential — replace any softened O-rings or corroded fittings immediately to keep injection timing and engine performance consistent.
The air starter, coded P51309-16, is a critical auxiliary system in the MAN L21/31 engine, enabling smooth and reliable engine startup. By using compressed air to drive a small turbine or motor, the air starter turns the engine crankshaft until the first combustion cycle begins. This robust system is particularly advantageous for large diesel engines, where electric starters are impractical. Dependable air starters are key to operational readiness and safety in marine and power generation applications.