Instructions on Replacing a PCV Valve

by Don Bowman

The PCV valve's job is to relieve the internal pressure in the engine caused by a percentage of burnt gases escaping past the piston rings and entering the oil pan. No engine can be built to such tolerances that no blow-by is present. Blow-by is the act of gases passing the rings and into the crankcase. These gases also contain elements that are harmful to the environment. The PCV system removes these gases and directs them back into the intake manifold for re-burning. The PCV valve itself is a one way valve.

Locate the PCV valve by looking for a 5/8 diameter hose connected to the throttle body or directly in front of it on a fuel-injected vehicle. Follow the hose to the valve cover or the center rear of the intake manifold. Generally the PCV valve is plugged into the valve cover. The vacuum caused by the air being drawn into the engine draws the crankcase pressure out of the engine through the PCV valve and through the throttle body or carburetor to be re-burned. Depending on the vehicle, it may be necessary to remove the air cleaner and air duct to gain access to the valve with the tools recommended.

Pull the PCV valve out of its grommet. Twist the valve while pulling it out of the hose.

Check the rubber grommet for cracks and tears and replace if needed.

Insert the new PCV valve into the hose and push it down into the rubber grommet securely. If applicable, replace any components which were removed in order to access the PCV valve.

Items you will need

About the Author

Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).