Mercury - Quicksilver Through Gear Case Flushing Kit Maintenance Accessory Rubber, Stainless & Plastic 44357Q2. Overview. Salt, silt, and debris can take a toll on your cooling system, but regular flushing keeps everything clean and running cool. The Mercury Marine 44357Q2 Quicksilver Through Gear Case Flushing Kit makes that easy. Designed for Mercury and Mariner outboards (20HP and up) and most MerCruiser sterndrives, this semi-universal kit connects directly to a standard garden hose for quic