This manual covers the YSM Series Marine Diesel Engines manufactured by Yanmar. These engines are engineered for reliability and performance in marine applications, offering robust solutions for a variety of maritime needs. The YSM series is designed to provide dependable power, ensuring efficient operation and longevity for boat owners and operators. This comprehensive service manual provides in-depth information for the servicing, repair, and maintenance of Yanmar YSM Series Marine Diesel Engines. It includes detailed instructions, accompanied by pictures and wiring diagrams, to guide users through routine maintenance and all servicing and repair jobs. The manual is designed to be user-friendly, enabling owners and technicians to perform necessary tasks efficiently, save on repair costs, and ensure the optimal performance of their engines.