TESTING

If any of the following operating problems occur, inspect the PCV system:

• Rough idle, not explained by an ordinary vacuum leak, or fuel delivery problem.
• Oil leaks past the valve cover, oil pan seals or even front and rear crankshaft seals not explainable by age, high mileage or lack of basic maintenance.
• Excessive dirtiness of the air cleaner cartridge at low mileage.
• Noticeable dirtiness in the engine oil due to fuel dilution well before normal oil change interval.

NOTE: An engine with badly worn piston rings and/or valve seals may produce so much blow-by that even a normally functioning PCV system cannot deal with it. A compression test should be performed if extreme wear is suspected.

The PCV system is easily checked with the engine running at normal idle speed (warmed up). Remove the PCV valve from the valve cover, but leave it connected to its hose. Place your thumb over the end of the valve to check for vacuum. If there is no vacuum, check for plugged hoses or ports. If these are open, the valve is faulty. With the engine off, remove the PCV valve completely. Shake it end to end, listening for the rattle of the needle inside the valve. Generally, if no rattle is heard, the needle is jammed (probably with oil sludge) and the valve should be replaced. If the valve is a threaded type, it may be necessary to use a thin probe inserted in the threaded end to check for plunger motion. If no motion is felt, replace the valve.

An engine which is operated without crankcase ventilation can be damaged very quickly. It is important to check and change the PCV valve at regular maintenance intervals.