This workshop service repair manual covers the Case/Isuzu 4HK1-6HK1 engine. While specific production years are not detailed, this internal combustion engine is engineered for robust performance and reliability. The manual provides comprehensive information for understanding and maintaining this engine, ensuring its continued operational efficiency. This manual serves as an essential resource for owners and mechanics alike. It includes detailed procedures for complete disassembly, step-by-step repair instructions, advanced troubleshooting guides, and essential technical specifications such as tightening torques. Coverage extends to critical systems including the cooling, fuel, exhaust, and electrical systems, along with the alternator and regulator. Maintenance checklists and procedures for components like the fuel filter are also provided, offering a complete reference for servicing and repair.