This service manual covers John Deere POWERTECH engines, specifically the 4.5L and 6.8L generations. These diesel engines are engineered for robust performance and reliability, featuring turbocharged induction and available in 4-cylinder (4.5L) or 6-cylinder (6.8L) configurations. Designed for demanding applications, the POWERTECH series embodies John Deere's commitment to quality and durability in engine technology. The CTM104 service manual provides comprehensive guidance for the maintenance, repair, and diagnostics of these engines. It details procedures for all major systems, including fuel, lubrication, cooling, air intake, exhaust, starting, and charging systems, as well as electrical engine control. Covered topics include General Information, Repair and Adjustments, Theory of Operation, Diagnostics, Tools and Materials, and Specifications, offering essential information for owners, technicians, and mechanics to ensure optimal engine performance and longevity.