This manual covers the MerCruiser D2.8L D-Tronic and D4.2L D-Tronic In-Line Diesel Marine Engines, part of the D-Tronic Series. These engines are designed for marine applications and feature electronic diesel injection, turbocharged induction, and integrated power steering systems. They are available in sterndrive (MCM) and inboard (MIE) configurations, utilizing ZF/Hurth transmissions and covered propeller shaft models. The engines are built with robust engineering for reliability and performance in demanding marine environments. This Factory Service Repair Manual provides comprehensive guidance for the maintenance and repair of these MerCruiser diesel engines. It details procedures for engine mechanical systems, electrical systems, fuel, cooling, intake/exhaust, drive systems, and power steering. The manual includes step-by-step repair instructions with photos and illustrations, along with common maintenance tasks, fluid checks, filter replacements, and system inspections. It is intended for dealers and service mechanics to ensure optimal operating condition and longevity of the D2.8L and D4.2L D-Tronic marine engines.