19315-ZY6-010 Thermostat Cover - Overview. The 19315-ZY6-010 Thermostat Cover is a critical component of Honda marine engine systems, designed to house and seal the thermostat efficiently. It supports the engine cooling system by ensuring the thermostat remains securely in place, which helps maintain the engine's optimal operating temperature and prevents overheating. This OEM part fits seamlessly within the existing hardware and contributes to reliable engine performance and durability.. Key Fe