This service manual provides comprehensive information for the Liebherr diesel engines D 9406/9408 and D 9306/9308. These engines are engineered for robust performance and reliability, suitable for demanding applications. This manual details procedures for maintaining and repairing these units, ensuring their continued operational efficiency. The scope of this manual is extensive, covering all aspects from initial technical descriptions and engine data to detailed repair procedures for individual components such as the cylinder head, pistons, crankshaft, and fuel system. It includes essential information on lubrication and coolant circuits, troubleshooting common issues, and outlines necessary torque specifications and adjustment values. This resource is designed to assist both novice do-it-yourself enthusiasts and experienced mechanics in effectively servicing and repairing these Liebherr engines.