Cummins C2871257 39MT Starter Motor Assembly

The C2871257 is a 24-volt 39MT series gear reduction starter motor designed for Cummins heavy-duty diesel engines including ISM, QSM11, ISX, QSX, and M11 series. Manufactured by Delco Remy to OEM specifications, this unit delivers 8.5 kW cranking power with an 11-tooth pinion engaging the engine flywheel ring gear. The starter features a clockwise rotation and SAE 3-bolt flange mounting configuration standard for Cummins industrial and on-highway applications. Internal construction utilizes high-torque permanent magnet or field coil design with copper and silver contact assemblies for reliable electrical conductivity under high-current starting cycles. The 39MT-HD (Heavy Duty) designation indicates reinforced drive housing and upgraded internal components for extended service life in severe duty cycles typical of construction machinery, long-haul trucking, and marine propulsion systems. OEM cross-references include Cummins part numbers 3103952, 5284086, and 5367753. This starter replaces earlier 2871252, 2871253, and 2871256 variants with improved thermal protection and engagement reliability.