This manual covers the Daewoo D427 Diesel Engine, specifically as used in Doosan 1550XL (DSL702) Skid Steer Loaders. The Daewoo D427 is engineered for reliability and performance across a variety of applications, with variants available to meet specific operational demands. This documentation provides comprehensive details on its design, operation, and maintenance. The purpose of this workshop manual is to guide qualified technicians and owners through the repair and maintenance of the Daewoo D427 Diesel Engine. It details general information, engine descriptions, operational procedures, maintenance schedules, fault diagnosis, and technical specifications. Adherence to the procedures outlined herein is essential for ensuring the continued optimal performance and longevity of the engine, and it assumes familiarity with the accompanying operation manual, particularly regarding safety regulations.