This manual covers the Yanmar YSE series of internal combustion diesel engines. Engineered by Yanmar Co., Ltd., these engines are designed for robust performance and reliability in demanding applications such as industrial machinery, agricultural equipment, and marine environments. The YSE series typically features a four-stroke, liquid-cooled design with electric start capabilities, offering efficient power generation for a variety of operational needs. Specific engine characteristics, including turbocharging and governor type, may vary depending on the individual model. The purpose of this English-language Service Repair Manual is to provide comprehensive guidance for the maintenance, repair, and technical understanding of the Yanmar YSE engines. It details essential procedures, troubleshooting steps, and technical specifications necessary for optimal engine operation and longevity. Owners, technicians, and mechanics will find valuable information on service intervals, fluid requirements, and inspection schedules, ensuring that these powerful diesel engines remain in peak condition throughout their service life.