4Runner. A seal that prevents oil from leaking out, or contaminants from entering The Engine Coolant Inlet Housing. Engine Coolant Thermostat Gasket. Engine Coolant Thermostat Seal. From 10/2017. From 11/2017. Gasket for Engine Coolant Water Inlet. O-Ring. Thermostat Housing Gasket. To 10/2017. To 11/2017. hsng. Neck. outlet. unit o - ring. Engine Flange O - Ring. Engine Housing. Engine Seal. Included with: Thermostat, Thermostat Housing, Thermostat Housing Part cannot be reused/reinstalled, Thermostat unit, Thermostat unit Part cannot be reused/reinstalled, Water Inlet, Water Inlet Part cannot be reused/reinstalled, Water outlet.