The Function of PCV Valves

The term PCV valve stands for positive crankcase ventilation. A PCV is a plain spring-loaded valve with a sliding pintle within it that increases or decreases airflow.

Pollution Technology

Plainly speaking, a PCV valve is a technological advancement that plays a critical role in reducing automobile emissions. Other parts that help reduce emissions include the catalytic converter, additives placed in gasoline and oxygen sensors, to name just a few.

The job of the PCV valve is to sends fumes from the engine’s crankcase back into the combustion chamber where these gases are burned. PCVs first appeared in cars in California in 1961 and, later, began to appear in all cars nationwide by the late 1960s. 

PCV Benefits

One of the most important benefits of PCV valves is its positive affect on the environment. Specifically, crankcase emissions are eliminated, one of the more significant contributors to air pollution. Fuel mileage is also improved as partly burned gases are harnessed and sent back to the engine for burning. As equipped, such engines run more efficiently and thereby consume less fuel.

With a working PCV valve, your car’s engine can last longer as this device prevents the accumulation of sludge and thwarts moisture build up. Moisture found within any engine is corrosive and will shorten the engine’s life if the PCV valve is malfunctioning. Signs of PCV valve failure include engine misfiring when idling, oil consumption or both. A manometer is used by mechanics to test whether the valve is stuck open or shut closed, and will need to be replaced if malfunctioning.


PCV valves should last to about 80,000 miles according to AGCO Automotive Corporation. That’s about the time when your engine will receive its first full tune up and will be something your mechanic will suggest replacing when you’re swapping out spark plugs and setting the timing. However, PCV valve failure can occur much earlier, such as at 50,000 miles, especially if the vehicle is driven fewer than 10 miles per trip.