Positive Crankcase Ventilation: Testing and Inspection

PCV System:

PCV VALVE TEST

1. With engine idling, remove PCV valve from the crankcase vent valve hose. If valve is not plugged, a hissing sound will be heard as air passes through the valve, and a strong vacuum should be felt when a finger is placed over the inlet of the valve.
2. Reinstall the PCV valve, then remove crankcase vent hose at valve cover. With engine idling, loosely hold a piece of stiff paper (such as a parts tag) over the opening in the valve cover. After allowing about a minute for the crankcase pressure to reduce, the paper should be drawn against the opening in the valve cover.
3. With engine off, remove PCV valve from crankcase vent valve hose and shake the valve. A rattling noise should be heard, indicating that the valve is free.
4. If the system passes the above tests, no further service is required. If not, replace the PCV valve and recheck the system. Do not attempt to clean the PCV valve.
5. With a new PCV valve installed, if the paper is not drawn against the crankcase inlet air cleaner opening with considerable force, it will be necessary to clean the vent hose or the passage in the throttle body. Also, the PCV hose will have to be cleaned or replaced.