According to another embodiment, a molten metal impeller comprised of a generally cylindrical body including a plurality of passages extending from a top surface to a side wall and a cap member secured to a top surface of the body. The cap member is shaped cooperatively to overlay the cylindrical body. The cap member includes a first side seated on the top surface and a second opposed side. The top surface includes one of a notch or a protrusion and the first side of the cap member includes one of a notch or a protrusion oriented to mate with the notch or protrusion of the body.