Caterpillar 421-8547 Seawater Auxiliary Pump Assembly

The Caterpillar 421-8547 is a gear-driven centrifugal auxiliary seawater pump designed for raw water cooling circuits on Caterpillar C15, C18, 3406E, and G3516C diesel engines. It is commonly deployed in marine propulsion and generator set applications, including C18 generator sets. The pump assembly features a cast iron housing with bronze impeller and stainless steel shaft for corrosion resistance in seawater environments. This unit supersedes previous part numbers 5N5757, OR7724, and 524-3160. The remanufactured equivalent is 20R-1686. It serves as a component of the 421-8548 pump group assembly. NSN 2930016249209 references this item for military logistics.