Passat. 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. Engine Coolant Thermostat Housing Bolt. Engine Water Pump Bolt. From 03/25/2014. Housing for the Engine Water Pump. Incl.Engine Coolant Thermostat Gasket,Housing and Thermostat. To 03/24/2014. Engine Coolant Thermostat Bolt. Engine Coolant Thermostat Housing Bolt. Engine Water Pump Bolt. Engine Water Pump Housing. Thermostat hsng. Thermostat unit bolt. Water pump ASSEMBLY bolt. Included with: Thermostat unit, Water pump assembly.