Positive Crankcase Ventilation: Description and Operation

(USA) Federal starting 1981, (USA) California starting 1980





1 Vent plate
2 Connection
3 Oil separator
4 Intake line
6 Return line
7 Check valve

The complete engine breathing system requires no maintenance.

The engine blow-by gases and cylinder crankcase vapors are flowing via vent plate (1), which is revited to cylinder head cover, and connection (2) to cyclonic oil separator (3), which is located in air cleaner housing.

From there, they are flowing by way of the intake line (4) in front of compressor and together with the intake air into the combustion chambers.

The oil separated in cyclonic oil separator (3) flows through return line (6) and check valve (7) installed in oil pan upper half toward oil pan. The check valve prevents that the vacuum in intake system will draw oil vapors out of oil pan.






Starting model year 1981, the vent line between cylinder head cover and air cleaner has been changed from oval to round for better flow characteristics (arrow).