This manual covers the Westerbeke 20B-TWO and 30B-THREE Marine Diesel Propulsion Engines, designed for reliable marine propulsion. These diesel engines are engineered for durability and performance in demanding marine environments. Westerbeke is recognized for its commitment to quality, ensuring these engines deliver consistent power and longevity for various marine applications. This Service Repair Manual provides comprehensive guidance for the maintenance and repair of your Westerbeke marine diesel engine. It includes detailed procedures, technical specifications, and troubleshooting information to assist owners and technicians. The manual is designed to help prevent premature failure and ensure optimal performance through routine, preventive maintenance, making it suitable for users of all experience levels.