Positive Crankcase Ventilation: Testing and Inspection

Crankcase Ventilation System Inspection/Diagnosis
Crankcase Ventilation (CV) System Inspection





^ Test for vacuum at the positive crankcase ventilation (PCV) dirty air hose where it connects to the vacuum orifice tube in the engine valley cover. There should be a manifold vacuum present at the hose. If there is no vacuum, inspect for a plugged hose, leaking hose or a plugged intake manifold passage.
^ If oil has accumulated in the intake, inspect for the following conditions:
^ Plugged vacuum orifice tube in the engine valley cover
^ Plugged, restricted, or leaking PCV dirty air hose
^ Plugged or restricted intake manifold passage
^ Excessive crankcase pressure or blow-by





Additional items to inspect:
^ Plugged or restricted PCV fresh air hose
^ Inspect the valve rocker arm cover, the oil pan, engine front cover, and other sealing areas for leaks

Results of Incorrect Operation
A plugged crankcase ventilation system may contribute to the following conditions:
^ A rough idle
^ Stalling or a slow idle speed
^ Oil leaks
^ Oil accumulation in the intake manifold
^ Sludge in the engine

A leaking hose may contribute to the following conditions:
^ A rough idle
^ Stalling
^ Unstable idle speed

The crankcase ventilation system has no serviceable components so no maintenance of the system is required.