Positive Crankcase Ventilation System

The crankcase ventilation system is used to consume crankcase vapors in the combustion process instead of venting vapors to the atmosphere. The system consists of two circuits, a primary (part load (1)) and a secondary (high load (2)) circuit. In both circuits the gases and oil vapors from the crankcase are returned via an internal ventilation into the cylinder head cover that has an internal oil separator (6). The separated oil from the blow-by gases flows back to the camshaft area through the oil drain valve (7). Inside the cam cover the gases are then separated into both circuits. The primary check valve (3) is positioned inside cam cover as part of primary circuit which prevents the crank case from pressure increase under turbo boost conditions. As a part of the secondary circuit the secondary check valve (4) is positioned inside cam cover. It prevents a bypass of the closed throttle at idle or coast down.

The gases flow either

• via the primary circuit through internal ducts of the cam cover and cylinder head directly into the intake manifold. The primary circuit is fully integrated, no external hoses or pipes.
• via the secondary circuit through the cam cover and an external blow-by hose to the turbocharger compressor inlet into the combustion chamber.

The blow-by module is no service part. In case of damage of a component of the blow-by module, the whole cam cover assembly must be replaced.

In case of a leaking gasket to the cylinder head the gasket can be replaced.