Positive Crankcase Ventilation: Description and Operation

OPERATION




To comply with engine emissions regulations, a CCV (Closed Crankcase Ventilation) system has been developed for the 6.7L Cummins diesel. The CCV system reroutes crankcase ventilation (blow-by) gases from the breather assembly back into the engine intake airflow to be used for combustion. The crankcase ventilation system uses a coalescing filter (2) which captures and filters crankcase blow-by gases and then returns oil directly to the sump.

The CCV system contains the following components:

- Valve Cover Assembly (7)
- Breather Filter (2)
- Breather Filter Cover (1)
- Crankcase Pressure Sensor (3)
- Crankcase Differential Regulator (CDR) Valve; a part of the breather filter cover (1)

The valve cover assembly (7) is made of a composite material. The cover has a recessed area for the breather filter and passages for oil draining from the breather filter, back to the crankcase. The drain tubes have one-way check valves (4), (5) and (6) that prevent oil from being forced up the tubes by excessive crankcase pressure.