The YANMAR 6LYA-UTE / 6LYA-STE Marine Diesel Engine represents a robust and powerful solution for marine applications. Engineered with a 6-cylinder, turbocharged, and intercooled configuration, these engines deliver exceptional performance, with models offering up to 355 mhp at 2300 rpm. Their design emphasizes reliability and efficiency, featuring a displacement of 6.5 liters and a forced lubrication system. The freshwater cooling system ensures optimal operating temperatures, contributing to the longevity and consistent operation of the engine in demanding marine environments. This Operation Manual provides comprehensive guidance for the YANMAR 6LYA-UTE / 6LYA-STE engines. It covers essential areas including product explanation, safe operation procedures, detailed maintenance and inspection schedules, and effective troubleshooting techniques. The manual also includes system diagrams to aid in understanding the engine's complex components. Its purpose is to empower owners, operators, and technicians with the knowledge necessary to maintain the engine's peak performance, ensure its longevity, and address any operational issues promptly and effectively.