This manual covers the 3JH3(B)(C)E(A), 4JH3(B)(C)E, and 4JH3CE1 Marine Diesel Engines. These engines are engineered for reliable performance in marine applications, offering robust construction and efficient operation. Designed for a variety of maritime uses, they represent a commitment to quality and durability in marine propulsion systems. This comprehensive Service Repair Manual provides detailed information essential for the maintenance, servicing, and repair of your marine diesel engine. It includes step-by-step procedures for basic engine parts, fuel injection equipment, intake and exhaust systems, lubrication, and cooling water systems, along with disassembly and reassembly instructions. Furthermore, the manual offers valuable troubleshooting guidance, technical specifications, and helpful diagrams, ensuring owners and technicians can effectively maintain the longevity and optimal performance of these engines.