This manual covers the Yanmar 6SY-STP2, 6SY655, and 8SY-STP marine engines. These engines are engineered for reliable performance in demanding marine environments, representing Yanmar's commitment to quality and durability. Designed for a range of marine applications, these engines are built to provide efficient power and long-term service, making them a trusted choice for boat owners and operators. This comprehensive English-language Factory Service/Repair/Workshop Manual provides detailed information for the maintenance, servicing, diagnosis, and repair of Yanmar Marine Engines. It includes step-by-step instructions with detailed diagrams for all repair procedures, covering essential systems such as the engine, fuel, cooling, lubrication, turbocharger, starter motor, alternator, and the Engine Management System. This manual is an invaluable resource for owners, mechanics, and technicians to ensure optimal performance and longevity of their Yanmar marine engines.