This comprehensive service manual covers the Hitachi 4HK1-6HK1 Isuzu Engine, providing detailed information for maintenance and repair. Designed to equip owners and technicians with factory-level knowledge, this manual ensures that all aspects of the engine's operation and upkeep are thoroughly understood. It is an essential resource for anyone seeking to maintain the reliability and performance of their Hitachi 4HK1-6HK1 Isuzu Engine. The scope of this manual is extensive, encompassing engine identification, general precautions, maintenance checklists, and detailed procedures for various engine components including the engine body, fuel system, cooling system, and electrical system. It also includes crucial sections on special tools, troubleshooting, servicing specifications, tightening torques, and disassembly. With step-by-step instructions, detailed illustrations, and advanced diagnostic guides, this manual serves as an indispensable tool for all repair and maintenance tasks.