Yamaha - Thermostat Cover Cooling System Housing 6FM-12413-00-1S. Overview. Cooling issues don't always come from major components-sometimes it's something simple like the thermostat cover not sealing right. I've seen small leaks or warped covers throw off the whole cooling system and cause inconsistent temps. This piece keeps everything contained and working together once the engine warms up. When it's solid and sealed properly, you don't have to think twice about your engine temperature.. Key Features. Thermostat Housing Protection - Encloses the thermostat to maintain proper coolant flow and system pressure.. Secure Sealing Surface - Helps prevent leaks and ensures consistent cooling system performance.. OEM Fitment Design - Built to Yamaha specifications for proper alignment and installation.. Heat-Resistant Construction - Designed to handle constant temperature changes during operation.. Cooling System Support - Works with the thermostat to regulate engine temperature effectively.