This Service Repair Workshop Manual covers the Yanmar 6SY-STP2, 6SY655, and 8SY-STP marine engines. These diesel engines, available in 6-cylinder and 8-cylinder configurations, are engineered for reliable performance in marine applications. Yanmar is recognized for its commitment to robust construction and durable engineering, ensuring these engines meet the demanding requirements of maritime operations. This manual provides comprehensive guidance for the service and repair of your Yanmar marine engine. It details essential procedures including periodic maintenance, fuel system service, cooling system service, lubrication, and specific component servicing for the turbocharger, starter motor, and alternator. Furthermore, the manual includes Engine Management System (EMS) service information and troubleshooting guidance to assist owners, mechanics, and technicians in maintaining optimal engine function and addressing potential issues effectively.