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.