Auxiliary Emission Control Systems: VOLVO: VOLVO: Operation

During idling and slow speed operation, crankcase gases are drawn into combustion chamber through oil filter cap and PCV valves on 6 cylinder or through flame guard and PCV valve on 4 cylinder. During high speed or full throttle operation, crankcase gases are drawn directly through hose to air cleaner.

Fig 1: Crankcase Ventilation System (4 Cylinder Models)

Courtesy of VOLVO CARS CORPORATION