Positive Crankcase Ventilation (PCV) System (Chevrolet Lumina 1)

1. The Positive Crankcase Ventilation (PCV) system serves to reduce the hydrocarbon content in exhaust gases by removing vapors from the engine crankcase. This is accomplished by circulating fresh air from the air cleaner through the crankcase, where it mixes with the blow-by gases and is then returned through the positive-pressure ventilation (PCV) valve to the intake manifold (see illustration).



2. The main components of the PVC system are the PCV valve, the filtered air intake hose and the vacuum hoses connecting these components to the engine and the EECS system.

3. To maintain idle speed, the PCV valve restricts flow when the intake manifold vacuum is high. In the event of abnormal operating conditions, the system design provides for the possibility of returning the breakthrough gases through the outlet pipe in the engine crankcase back to the air filter, from where they enter the engine and are consumed during fuel combustion.

4. Checking and replacing the forced ventilation valve and its filter is discussed in section 30 Chapter 1.