Yamaha - Impeller Housing Water Pump Component 6HH-51312-00-00. Overview. When you're dealing with Yamaha cooling systems, the impeller gets most of the attention, but the housing is just as important. I've seen plenty of pumps rebuilt where the old housing was worn or scored, and the new impeller never had a chance to work right. The Yamaha Impeller Housing 6HH-51312-00-00 is what keeps everything sealed and moving water the way it should. If the housing isn't in good shape, your cooling system