Positive Crankcase Ventilation: Description and Operation

NOTE: Numbers in parentheses ( ) indicate a component or tool in the associated illustration.

Function At Idle Speed Position And Mid-Load
(Throttle valve (15) closed or only slightly open high intake manifold vacuum).

The crankcase (1) is vented in part load via the combination support (4) of the vent (2b) of the vent pipe (7) through a 2 mm dia. restriction drilling (8) in the manifold of the vent pipe (7a) to me intake manifold (10).

Entrained engine oil is separated out in the combination support (4) and passed along the oil outset pipe (5) into the oil pan (6).

The vacuum which is thus produced in the crankcase draws in fresh air from the intake air line (10a) through the air admission and vent connections (14) and (14a).

The addition of fresh air is an additional measure to prevent the formation of sludge in the engine oil. The vent connections (14) and (14a) have a scoop adapted to the pressure fluctuations in the intake air line (10a).

Function At Top Part Load, Up To Full Load
Throttle valve (15) open:
At full load the entire ventilation quantity is passed through the oil separators (13) and (13a) in the cylinder head cover (11) to the air admission and vent connections (14) with 9 mm diameter reduction and (14a) with 7 mm diameter reduction of the intake air line (10a), to the intake manifold (10) to the combustion chambers.