This Technical and Repair Manual provides comprehensive information for the Iveco NEF Series diesel engines, specifically designed for marine and industrial applications. These engines, including models N40-ENT-M25, N60-ENT-M37, and N60-ENT-M40, are recognized for their robust engineering and reliable performance in demanding environments. This manual serves as an essential resource for understanding the intricacies of these internal combustion engines, ensuring their optimal operation and longevity. The purpose of this English-language manual is to guide owners, technicians, and mechanics through all aspects of engine maintenance, diagnostics, and repair. It covers a wide range of topics, including general overview, technical data, electrical equipment, diagnostic procedures, routine and preventive maintenance, servicing operations on installed engines, and detailed overhaul instructions. By utilizing the information contained herein, users can effectively maintain and troubleshoot their NEF Series engines, ensuring peak efficiency and adherence to safety regulations.