Passat L4-1984cc 2.0L DOHC (1991)
Crankcase Breather: Description and Operation
All internal combustion engines produce small amounts of blow-by gasses. These are gasses that by-pass the piston rings and pass into the crankcase.
These blow-by gasses are the result of the high pressure developed within the combustion chambers during the combustion process. They contain
undesirable pollutants. To prevent blow-by gasses from entering the atmosphere, the PCV system is used. The crankcase ventilation system vents the
blow-by gasses into the intake system to be burned, and allows for proper crankcase ventilation.
Crankcase Housing Breather Hoses
The system incorporates a crankcase breather and screen #3 located on the engine block. The breather vent hose #1 is attached between the crankcase
breather and the air intake. A calibrated vacuum orifice is connected between the breather hose and the vacuum hose. The restrictor orifice #4 allows
vacuum hose #2 to vent blow-by gasses into the intake manifold. This helps control crankcase pressure.