This manual provides comprehensive service and repair information for the Hitachi 4HK1-6HK1 Isuzu Engine. Designed for both experienced mechanics and do-it-yourself enthusiasts, it offers detailed instructions to ensure the proper functioning and maintenance of your engine. The manual is an essential resource for anyone seeking to understand and work on this specific engine model, aiming to keep it operating at peak performance. The scope of this manual is extensive, covering all critical aspects of engine maintenance and repair. It includes detailed sections on engine identification, general precautions, disassembly and assembly procedures, maintenance checklists, and specific checks and maintenance routines. Furthermore, it delves into specialized tools, engine body components, fuel and cooling systems, exhaust and electrical systems, and troubleshooting guidance. With detailed specifications, tightening torques, and wiring diagrams, this manual serves as a complete workshop guide for all your engine service needs.