This troubleshooting manual covers the NEW HOLLAND ISUZU KOBELCO 4HK1 and 6HK1 engines. These engines are known for their robust construction and reliable performance, designed to meet the demanding requirements of various industrial and agricultural applications. Their engineering prioritizes durability and efficiency, ensuring consistent operation in challenging environments. This manual provides comprehensive guidance for diagnosing and resolving issues specific to the 4HK1 and 6HK1 engine series. It details common problems, diagnostic procedures, and recommended repair steps, along with essential technical specifications and safety precautions. The information contained herein is intended to assist owners, technicians, and mechanics in maintaining the optimal performance and longevity of these engines.