GM Service Manual Online
For 1990-2009 cars only

The compressed combustion gas which escapes past the piston rings into the crankcase is known as blow-by gas. Blow-by gas contains large amounts of carbon monoxide (CO) and hydocarbon (HC). The positive crankcase ventilation (PCV) system prevents the blow-by gas from being emitted into the atmosphere. The PCV system routes the crankcase blow-by gas back into the intake system where the blow-by gas becomes part of the combustion process.

Results Of Incorrect Operation

A plugged oil separator or hose may cause any of the following conditions:

    • A rough engine idle
    • Engine stalling or low engine idle speed
    • High engine crankcase pressure
    • Engine oil leaks
    • Engine oil in the air cleaner
    • Oil sludge in the engine
    • Engine oil consumption
    • Excessive exhaust emissions

A faulty separator or hose may cause any of the following conditions:

    • A rough engine idle
    • Engine stalling
    • High engine idle speed
    • Incorrect engine crankcase pressure
    • Excessive exhaust emissions
    • Engine oil consumption