GM Corvette 1963-1982 Repair Guide

Positive Crankcase Ventilation (PCV) System

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OPERATION



See Figures 1, 2, 3 and 4

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Fig. Fig. 1: Schematic of the Positive Crankcase Ventilation (PCV) system flow



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Fig. Fig. 2: View of the crankcase ventilation system components-1971-72 454 engines



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Fig. Fig. 3: Exploded view of the components of the PCV system-1973-75 vehicles



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Fig. Fig. 4: Emission Component Locations (350 V8)

In this system, crankcase vapors are drawn into the intake manifold to be burned in the combustion chambers; instead of merely venting the crankcase vapors into the atmosphere. An added benefit to engines equipped with this system is that the engine oil will tend to stay cleaner for a longer period of time; therefore, if you notice the oil in your engine becomes dirty very easily, check the functioning of the PCV valve. The valve should rattle when shaken, indicating that sludge has not stopped operation of the valve, and the PCV line to the carburetor or the intake manifold must be clear. Engines which use a PCV system are calibrated to run richer, to compensate for the added air which accompanies the crankcase vapors to the combustion chambers. If the PCV valve or line is clogged, the engine idle will tend to be rough due to the excessively rich mixture. Maintenance is covered in General Information And Maintenance .

 
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