Blazer 4WD V6-4.3L VIN X (2005)
Positive Crankcase Ventilation: Description and Operation
Crankcase Ventilation System Description
General Description
A crankcase ventilation system is used to consume crankcase vapors in the combustion process instead of venting them to the atmosphere. Fresh air
from the intake system is supplied to the crankcase, mixed with blow by gases and then passed through a calibrated orifice into the intake manifold.
Operation
The primary control is through the positive crankcase ventilation (PCV) orifice which meters the flow at a rate depending on inlet vacuum. The PCV
orifice is an integral part of the valve cover. If abnormal operating conditions occur, the system is designed to allow excessive amounts of blow by
gases to back flow through the crankcase vent into the intake system to be consumed by normal combustion.
Results of Incorrect Operation
A plugged orifice may cause the following conditions:
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Rough idle
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Stalling or slow idle speed
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Oil leaks
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Sludge in engine
A leaking orifice may cause the following conditions:
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Rough idle
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Stalling
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High idle speed
