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CLOSED CRANCKCASE VENTILATION There are two variations of this system viz. the positive crankcase ventilation and the fixed orifice system. In the former, filtered air from the carburetor air cleaner is introduced in the crankcase from where it carries away the blow by gases and the gasoline vapours enter the engine combustion chamber alongwith fresh charge and are burnt there.
In the fixed orifice system, a fixed orifice in the base of the carburetor takes the place of the PCV valve. The blow by gases are diverted to the inlet manifold through this orifice. In both these types of closed crankcase ventilation systems, the sludge and the other similar elements
during the course of time, clog the PCV valve or the orifice which may decrease and ultimately stop the flow of the blow by gases altogether, which would affect the engine performance very seriously. A coating of
oil on the air cleaner filter, apart from various engine troubles, indicates that service of
the system is needed urgently, which mainly requires the cleaning of the PCV valve or the orifice, the air cleaner filter hoses etc.
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