This workshop service repair manual covers Yanmar marine engines, specifically models 6SY-STP2, 6SY655, and 8SY-STP. These internal combustion engines are designed for marine propulsion and feature turbocharging, as indicated by 'STP' in their model designations. Yanmar is recognized for its engineering quality and reliable marine propulsion solutions, ensuring robust performance for demanding maritime applications. This comprehensive manual is designed for a wide range of users, from first-time owners to professional technicians. It provides detailed information on periodic and preventive maintenance to prevent premature failure and unnecessary repairs. The manual covers essential systems including the engine, fuel system, cooling system, lubrication system, turbocharger, starter motor, alternator, and the engine management system (EMS). It also includes troubleshooting guidance and technical specifications to assist in maintaining and repairing your Yanmar marine engine.