While transiting the Malacca Strait in heavy seas, the vessel experienced a sudden main engine overload trip accompanied by a heavy metallic thud. Upon resetting and turning the engine on turning gear, the indicator cocks showed air blowback at incorrect angles. Physical measurement of the crank web balance marks revealed that Cylinder No. 4 crankpin had physically slipped in the web bore by 18.5° counter-clockwise due to a severe hydraulic lock (fuel leak into the combustion chamber during a br
