Positive Crankcase Ventilation: Testing and Inspection

INCORRECT [1][2]PCV OPERATION:

1. A plugged PCV valve or hose may cause:
a. Rough idle.
b. The engine stalls or idle speed decreases.
c. Oil in air cleaner.

2. A leaking valve or hose can cause:
a. Rough idle.
b. Stalling.
c. High idle speed.

Clean Air Intake:

PCV Valve:

TEST DESCRIPTION:

This test is to see if the PCV system is functioning properly.

1. Check for a correct PCV valve and a properly mounted valve into the rubber gromment. Make sure the hose(s) and clamp(s) are tight, and in place.
2. Start the engine, and let idle.
3. Remove PCV valve from valve cover, and place thumb over valve.
4. Engine speed should drop, and vacuum should be felt.
5. If no vacuum is present, check for a clogged PCV valve, hose, or intake manifold port.
6. Remove engine oil dipstick and install a vacuum gauge on dipstick tube.
7. Run the engine at 1500 rpm for 30 seconds, and then take a vacuum gauge reading at that same engine speed. If vacuum is present, then system is okay. If no vacuum is present, the engine may not be sealed and/or drawing in outside air. If pressure registers on the gauge, check for a plugged hose or excessive engine blow-by.
8. Turn the engine off, and remove the PCV valve from hose. Shake the PCV valve and listen for a rattle. If a rattle was not heard, replace the valve.