D100 1/2 Ton Pickup 2WD V8-318 5.2L VIN Y FI (1988)
Positive Crankcase Ventilation: Description and Operation
Positive Crankcase Ventilation (PCV) System
SYSTEM OPERATION
The purpose of the PCV system is to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions created by engine blow-by. This system is a
closed crankcase ventilation system that consists of a PCV valve, a hose extending from the PCV valve to the throttle body, a crankcase inlet air filter,
and a hose connecting the filter to the air cleaner assembly.
The PCV system operates on manifold vacuum: Fresh air is drawn in through the air cleaner and crankcase inlet filter, into the engine, and the vapors
that come out through the PCV valve are blow-by gases. These gases are drawn through the PCV hose and into the throttle body, they mix with the
calibrated air/fuel mixture, and get burned and expelled with the exhaust gases.