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.
  Fig 1: View Of Positive Crankcase Ventilation (PCV) Dirty Air Hose

  Courtesy of GENERAL MOTORS CORP.
• 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

Fig 2: Identifying PCV Fresh Air Hose

Courtesy of GENERAL MOTORS CORP.

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