Yamaha - Thermostat Cover Cooling System Housing 6H4-12413-00-1S. Overview. I've seen cooling issues come down to something as simple as a bad seal around the thermostat housing. This cover keeps everything contained and flowing the way it should once the engine warms up. If it's warped, cracked, or not sealing right, you can end up chasing temperature problems that don't make sense at first. It's a straightforward part, but it plays a key role in keeping the cooling system tight and reliable.. 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 operation.. OEM Fitment Design - Built to Yamaha specifications for proper alignment and installation.. Heat-Resistant Construction - Designed to handle constant temperature changes during engine operation.. Cooling System Support - Works with the thermostat to regulate engine temperature eff