This service manual covers the David Brown Diesel Engine models AD4-25 and CAD4-30. These engines are known for their robust construction and reliable performance, making them suitable for a variety of demanding applications. Their engineering emphasizes durability and efficiency, ensuring consistent operation under challenging conditions. This comprehensive manual provides detailed information essential for the maintenance, repair, and servicing of the David Brown AD4-25 and CAD4-30 diesel engines. It includes in-depth procedures, technical specifications, and troubleshooting guidance designed to assist owners, technicians, and mechanics in keeping these engines in optimal working order and ensuring their longevity.