Positive Crankcase Ventilation: Description and Operation

Crankcase Ventilation







A head vent with valves covers that dissipate the blow-by gases is used to ventilate the positive crankcase. A labyrinth for coarse separation is integrated in the valve covers. The gas flows through flexible plastic lines to the inner V on the engine block, where the oil separator module is located. The coolant ducts are integrated into the oil separator module. The oil separator module doubles up as a cover that closes off the engine block. The gases are purified in two cyclones that operate in parallel. If the gas flow is too high, a bypass valve opens to prevent the pressure inside the crankcase from exceeding permitted levels. After purification, the gases flow directly into the air-charging module through the air-charging module connection.

The oil accumulates in a collection chamber in the lower part of the oil separator. An oil drain valve closes off the collection chamber while the engine is running. The pressure inside the crankcase forces the oil drain valve against the sealing face. The collection chamber is large enough to collect all the oil generated during the time the engine takes to consume a full tank of fuel. Another drain valve for draining condensed fuel vapours or water is located in the area below the pressure-regulating valve.

Connection to the air-charging module







Blow-by gases are directed into the air-charging module from underneath. An intermediate piece seals the feed line against the air-charging module. The opening on the air-charging module is conical in shape to allow for easier insertion of the intermediate piece. When the intermediate piece is fitted, a lug secures the component in the correct position at the positive crankcase ventilation output.