Yamaha - Thermostat Cover Cooling System Housing YF1-58417-32-60. Overview. When you're servicing a Yamaha cooling system, the thermostat housing area is one place you don't want leaks or corrosion. The Yamaha Thermostat Cover YF1-58417-32-60 keeps the thermostat secured and seals the cooling passage so water flows through the engine the way it should. It's a small part, but it plays a big role in maintaining stable operating temperature. When everything is sealed properly, the engine warms up c