This genuine Yanmar water pump, part number 121000-42100, is designed for reliable and efficient cooling in various Yanmar marine and industrial engines. It is a critical component for maintaining engine temperature and preventing overheating. This pump is an OEM replacement for several Yanmar engine models, including 2GM, 2GM20, 3GM, 3GM30, 3YM20, 3YM30, 3JH2E, 3JH3E, 4JH2E, 4JH3E, 4JH4E, 4JH4AE, 4JH4-HTE, 4JH4-TE, 4JH5E, 4JH80, 4JH110, 4JH45, 4JH57, 4JH6E, 4JH60, 4JH75. It replaces previous Yanmar part numbers 121000-42101, 121000-42102, 121000-42103, 121000-42104, 121000-42105, and 121000-42106.