This manual covers the Hyundai/Yanmar 3TNV/4TNV Series industrial diesel engines, designed for robust performance in demanding applications. These water-cooled engines, available in naturally aspirated and turbocharged variants, are integral to equipment such as the Hyundai Mini Excavator 5 Ton 7 Series, skid steer loaders, and Yanmar diesel generators. The comprehensive coverage ensures that users can maintain and operate these engines with confidence, leveraging their inherent reliability and engineering quality for optimal productivity. The purpose of this service and repair manual is to provide detailed guidance for maintenance, troubleshooting, and technical understanding of the 3TNV/4TNV Series engines. It encompasses a wide range of critical systems, including lubrication, cooling, fuel, and electronic control, alongside engine electrical components like the alternator and starter motor. This resource is designed to assist owners, mechanics, and technicians in performing routine maintenance, diagnosing and resolving issues, and ensuring the longevity and efficient operation of their equipment.