This manual covers the David Brown Diesel Engine AD4-25 and CAD4-30 models. These engines are known for their robust construction and reliable performance, designed for demanding applications. Their engineering prioritizes durability and efficiency, making them a trusted choice for various industrial and agricultural uses. The purpose of this Factory Service Repair Manual is to provide comprehensive guidance for the maintenance, repair, and servicing of the David Brown Diesel Engine AD4-25 and CAD4-30. It details essential procedures, technical specifications, and troubleshooting information, enabling owners and technicians to ensure optimal engine operation and longevity.