This workshop service repair manual covers Caterpillar ACERT engines, including the C-11, C-13, C-15, C-16, and C-18 engine families. These inline 6-cylinder diesel engines feature ACERT Technology for advanced combustion and emission control, along with turbocharged and aftercooled induction systems. Engineered for robust performance and reliability, these engines are designed for demanding applications. The manual addresses multiple years and generations of ACERT engines, providing comprehensive information for their upkeep and operation. The purpose of this English-language manual is to provide complete service and repair procedures for Caterpillar ACERT engines. It details essential maintenance tasks, including scheduled maintenance, oil change intervals, coolant types, and filter replacement, tailored to specific engine models and applications. Additionally, the manual offers guidance on troubleshooting and technical specifications, empowering owners, mechanics, and technicians to effectively maintain and repair these powerful diesel engines, ensuring their continued optimal performance and longevity.