Positive Crankcase Ventilation: Testing and Inspection

WARNING: APPLY PARKING BRAKE AND/OR BLOCK WHEELS BEFORE PERFORMING ANY TEST OR ADJUSTMENT WITH THE ENGINE OPERATING.

1. With engine idling, remove the hose to the fixed orifice fitting. If the fitting is not plugged, a hissing noise will be heard as air passes through the fitting. A strong vacuum should also be felt when a finger is placed over the fitting inlet.
2. Install the fixed orifice fitting. Remove the make-up air hose from the grommet on the engine valve cover. Hold a piece of stiff paper (parts tag) loosely over grommet.
3. After allowing approximately 1 minute for crankcase pressure to reduce, the paper should draw up against the grommet with noticeable force.
4. Replace the fixed orifice fitting and retest the system if it does not operate as described in the preceding tests. Do not attempt to clean the old fixed orifice fitting.
5. If the engine does not draw the paper against the grommet after installing the new fitting, replace the fixed orifice fitting hose.