This operation manual pertains to the Yanmar YSM, YSMB, YSMBG, YSM12, and YSM12G series diesel engines. These engines are engineered for reliable operation and are powered by diesel fuel. They are designed for a variety of applications requiring robust diesel power. The quality of Yanmar engineering ensures dependable performance for their intended use. This manual provides comprehensive guidance for the operation and maintenance of your Yanmar diesel engine. It covers essential topics including engine installation, startup procedures for new engines, methods of operation, regular inspection and maintenance schedules, and troubleshooting simple malfunctions. Additionally, the manual includes information on fuel and lubricating oil specifications, electrical wiring diagrams, and safety guidelines to ensure proper and safe use of the engine.