Sierra 18-3017 Water Pump Impeller for MercurySierra replacement water pump impeller for Mercury and MerCruiser engines. This impeller fits MCM and outboard applications. All Sierra engine parts are manufactured to meet or exceed OEM requirements.Features: For Use On All #1, R, MR, and Alpha units thru S/N D494568. Sierra ; Also For Raw Water Pump On 190 IB S/N 1564539-1720903 & 225 IB S/N 1539620-2278646; Fits MCM & outboard applications; Uses a brass insert; Interchangeable with: MerCruiser Stern Drive; 47-89984T3; 47-89984T4; 47-30221; 47-65960; 47-65960; Mallory; 9-45306; Mercury Marine; 47-89984T4; 47-30221; 47-65960; 4789984; 47-899844; 47-899842; 47-85460; 47-89984T3; Chrysler/Force/US Marine; 47-803631T; 47-F694065; EMP; 47-00001; GLM; 89840; Pro Marine; 89984; Redline; RL3017;