2019-21. Water pump bolt. A threaded rod with a drive head (such as hex, 12 point, torx, etc.) on one end used to secure The Engine Coolant Thermostat to it's mounting point. A threaded rod with a drive head (such as hex, 12 point, torx, etc.) on one end used to secure The Water Pump Housing to it's mounting point. Engine Coolant Thermostat Housing Bolt. Engine Water Pump Bolt. hsng. unit. Engine Coolant Housing. HEXAGON - HEAD 6. Included with: Thermostat, Thermostat Housing, Thermostat Housing Part cannot be reused/reinstalled, Thermostat unit, Thermostat unit Part cannot be reused/reinstalled, Water Pump, Water Pump assembly.