This Workshop Service Manual (WSM) provides comprehensive repair and service information for the Volvo Penta 280-DP sterndrive, a robust Inboard/Outboard (I/O) unit designed for marine applications. While specific production years are not detailed, this manual covers a range of model years for the 280-DP, which is typically paired with gasoline engines of varying displacements and power outputs, from 3.0L to 5.7L and 130 to 300+ HP. The 280-DP features a Duoprop sterndrive system and a raw water-cooled lubrication system, engineered for reliability and performance in demanding marine environments. The purpose of this manual is to serve as a definitive guide for all services, repairs, routine maintenance, and troubleshooting of the Volvo Penta 280-DP. It includes detailed step-by-step instructions, wiring diagrams, and technical specifications designed to assist owners, mechanics, and technicians in maintaining the optimal performance and longevity of their equipment. By providing essential knowledge and clear guidance, this manual aims to facilitate cost-effective repairs and enhance understanding of the unit's systems, ensuring efficient operation and extended service life.