Mercury Water Pump Kit | Sierra 18-3319 Water pump repair kit with housing & base replaces Mercury 46-42579AA4 Sierra water pump kit Includes water tube guide, impeller, housing, base, water pump gasket, grommet, 2 drain gaskets, water pump base to gear housing gasket, 2 water pump gaskets, seal ring, plate, 6 o-rings and gasket Fits specified Mercury/Marine outboards Replaces Mercury 46-42579A4 Replaces Mallory 9-48306