This shop service manual provides comprehensive repair and maintenance information for diesel engines, specifically covering the 444 Engine (SA, SB, SC, SD, SF) and the 448 Engine (DA, DB, DC, DD, DF). Designed for DIY repair and maintenance, this manual is an essential resource for understanding and servicing these robust diesel engines. It details technical data, incorporates diagrams and instruction pictures to aid in understanding complex procedures, and outlines the necessary tool requirements for effective repairs. The purpose of this English-language manual is to guide users through all aspects of engine service, from general information and system descriptions to detailed maintenance procedures and fault finding. It covers critical systems including the fuel, cooling, lubrication, electrical, induction, and exhaust systems, as well as the base engine itself. With step-by-step guides, test procedures, and care and safety information, this manual empowers owners and technicians to maintain the reliability and performance of their diesel engines.