3.6 & 2.8 LITER. A circular disk covered in rubber or plastic with a hole in the center where the edge is sometimes tensioned by a spring that prevents fluid from leaking at the Engine Coolant Outlet Housing. Engine Coolant Outlet Gasket. Engine Coolant Outlet O-Ring. O-Ring. Outlet Flange. Coolant O - Ring. Pipe. Included with: Water Outlet.