Positive Crankcase Ventilation: Testing and Inspection

PCV VALVE

Fig. 17 Vacuum Check At PCV:

1. With engine idling, remove the PCV valve from cylinder head (valve) cover. If the valve is not plugged, a hissing noise will be heard as air passes through the valve. Also, a strong vacuum should be felt at the valve inlet.

Fig. 18 Vacuum Check At Valve Cover Opening:

2. Return the PCV valve into the valve cover. Remove the fitting and air hose at the opposite valve cover. Loosely hold a piece of stiff paper, such as a parts tag, over the opening (rubber grommet) at the valve cover.
3. The paper should be drawn against the opening in the valve cover with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce.

Fig. 19 Shake:

4. Turn engine OFF and remove PCV valve from valve cover. The valve should rattle when shaken.
5. Replace the PCV valve and retest the system if it does not operate as described in the preceding tests. Do not attempt to clean the old PCV valve.
6. If the paper is not held against the opening in valve cover after new valve is installed, the PCV valve hose may be restricted and must be replaced. The passage in the intake manifold must also be checked and cleaned.
7. To clean the intake manifold fitting, turn a 1/4 inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with shop air. If necessary use a smaller drill to avoid removing any metal from the fitting.