Positive Crankcase Ventilation Valve: Testing and Inspection

PCV Valve Test:

NOTE: Perform both checks if there is a problem suspected in the PCV system.

With Engine Idling, Check for Vacuum at Valve

1. Remove PCV valve from rocker cover, a hissing sound should be heard.
2. Place a finger over the inlet of the valve, a strong vacuum should be felt.
3. Install the PCV valve, then remove crankcase inlet air cleaner. With engine idling, loosely hold a piece of stiff paper (such as a parts tag) over the opening in the rocker arm cover. After allowing about a minute for the crankcase pressure to reduce, the paper should be drawn against the opening in the rocker arm cover.
4. If the paper is not drawn against the crankcase inlet air cleaner opening with considerable force, check the PCV valve, the passage in the throttle body and the [1][2]PCV hose for restrictions.

With Engine Off, Check for Valve Movement

1. Remove and shake the PCV valve, a rattling noise should be heard, (valve is not stuck).

DIAGNOSIS

- If A strong vacuum is felt and the PCV valve rattles, the system is operating properly and no further testing is necessary.

- If no vacuum is felt and the PCV valve rattles, then the intake plenum and/or the crankcase vent hoses need to be cleaned or replaced. (Do not attempt to clean valve).

- If PCV valve does not rattle when shook, replace valve. (Do not attempt to clean valve).