This manual covers the Yanmar 2TD, 3TD, and 4TD Marine Diesel Engine Series. These in-line diesel engines are water-cooled and utilize compression ignition, typically with an electric start system and forced lubrication. Designed for marine applications, these engines offer reliable performance and are engineered for durability. Their specific power output varies depending on the exact model and tuning. This comprehensive factory service and repair manual provides essential information for maintaining and troubleshooting your Yanmar marine diesel engine. It details procedures for the fuel system, intake and exhaust, lubrication, cooling, electrical systems, and stern equipment. The manual also includes technical specifications and troubleshooting guidance, ensuring that owners, mechanics, and technicians have the necessary resources to keep these engines operating at peak efficiency.