The Caterpillar 3126 HEUI engine is a robust and reliable power unit designed for demanding applications. This turbocharged, 6-cylinder engine features a HEUI fuel system for precise electronic control and hydraulic actuation. With a displacement of 7.2 liters, it offers a versatile power output ranging from 170 to 280 horsepower and torque from 470 to 750 lb-ft, making it suitable for a wide array of heavy-duty vehicles and equipment. Its liquid-cooled design and robust construction ensure consistent performance and longevity in challenging environments. This Service and Repair Manual provides comprehensive guidance for the Caterpillar 3126 HEUI engine. It covers essential maintenance procedures, including recommended oil type, capacity, and service intervals, as well as filter replacement guidelines. Detailed technical specifications, troubleshooting information, and repair instructions are included to assist owners, mechanics, and technicians in maintaining optimal engine performance and ensuring the longevity of the unit. This manual is presented in English and is designed to be a definitive resource for all service-related needs.