This Service Repair Manual covers the Yanmar 2T and 3T Marine Diesel Engines, designed for reliable marine propulsion. These engines utilize diesel fuel and are built with engineering quality to ensure dependable performance in demanding marine environments. This manual is intended for owners and technicians seeking comprehensive information on maintaining and operating these engines. This manual provides detailed guidance for the maintenance and repair of your Yanmar marine diesel engine. It includes step-by-step instructions with illustrations for periodic servicing, engine disassembly and reassembly, troubleshooting common engine issues, and proper engine storage procedures. Additionally, it covers major engine structures, fuel and lubricating oil information, and essential maintenance standards, making it an indispensable resource for both do-it-yourselfers and experienced mechanics.