This manual covers the Yanmar 6LYA-UTE and 6LYA-STE marine diesel engines. These engines are engineered for robust performance and reliability in demanding marine applications. Featuring a 6-cylinder, turbocharged configuration with a displacement of 6.453 liters, they offer significant power output, with the 6LYA-UTE typically producing 240 mhp and the 6LYA-STE delivering 280 mhp at 2400 rpm. Their direct injection fuel system ensures efficient combustion and dependable operation. This comprehensive Workshop Service Repair Manual provides detailed information for the maintenance and repair of your Yanmar marine diesel engine. It includes step-by-step instructions with accompanying images for all service and repair procedures, covering everything from routine maintenance, such as oil and filter changes, to more complex troubleshooting and repair tasks. Essential technical specifications, safety guidelines, and information on compatible transmissions are also included, empowering owners and technicians to keep the engine in optimal condition.