Crank Case Ventilation System (PCV, CCVV)


All current BMW engines incorporate a pressure-controlled crankcase ventilation system. The crankcase ventilation systems use various different crankcase ventilation valves depending on the engine type.

Although the valves all look different, they function similarly using a spring and diaphragm assembly to control the crankcase pressure. A properly functioning pressure control valve is designed to maintain a slight vacuum (approx. 10-15 mbar) in the crankcase, which assures reliable crankcase venting during all engine operating conditions.

A malfunctioning crankcase ventilation valve may cause the following complaints:

• Engine runs rough

• Whistling noise from the crankcase ventilation valve

• Check Engine Light on – possible DME faults stored: misfire on all cylinders, oxygen sensor/mixture faults, etc.

• Milky/beige substance found on valve cover cap and inside the valve cover gasket and CCVV assembly

While getting this job performed on your vehicle, it is suggested to also do the oil filter housing/valve cover gasket, and an oil change to get rid of the current condensation that is stored within the system.