This manual covers the Volvo Penta 251DOHC, an internal combustion engine featuring an inline cylinder configuration and DOHC valve system. While specific production years and detailed performance metrics are not provided, this engine is engineered for robust operation and reliability in its intended applications. Its design emphasizes efficient power delivery and durability, making it a dependable choice for various industrial and marine uses. This comprehensive service manual provides essential information for the repair, maintenance, rebuilding, and refurbishment of the Volvo Penta 251DOHC. It details scheduled maintenance intervals, fluid capacities, and recommended fluid types, ensuring optimal performance and longevity. The manual is written in English and serves as an indispensable resource for owners, technicians, and mechanics seeking to understand and service this engine effectively.