This document pertains to Case 4-390, 4T-390, and 4TA390 engines. These inline, four-cylinder diesel engines are liquid-cooled and feature compression ignition. Depending on the specific application and configuration, they can be naturally aspirated or turbocharged, with a displacement of 3.9 liters (236 cu in). Power output varies accordingly, and emission standards are dependent on region and usage. These engines are designed for robust performance and reliability across various demanding applications. This Workshop Service Repair Manual provides comprehensive information for the maintenance and repair of Case 4-390, 4T-390, and 4TA390 engines. It covers essential procedures, technical specifications, and diagnostic guidance necessary for optimal engine performance and longevity. The manual is intended for owners, mechanics, and technicians, offering detailed instructions on scheduled maintenance, fluid capacities, and troubleshooting. Adherence to the guidelines within this manual will ensure the continued efficient operation and proper upkeep of your Case engine.