This repair manual covers MAN D2866-LE Series and D2876-LE Series marine diesel engines, specifically models D 2866 LE 401, 402, 403, 405 and D 2876 LE 301, 403. These engines are engineered for reliable marine propulsion, utilizing diesel fuel and featuring robust construction for demanding maritime applications. The manual details essential systems including the cooling, lubrication, fuel, intake, exhaust, valve timing, crankgear, pistons, and cylinder head assemblies, along with various attachments. The purpose of this comprehensive English-language repair manual is to provide detailed guidance for the maintenance and repair of these MAN marine diesel engines. It includes technical specifications, diagrams, photo illustrations, and schemes to assist owners, mechanics, and technicians. By following the procedures outlined, users can ensure the optimal performance and longevity of their marine propulsion systems, covering all aspects from routine servicing to in-depth repairs.