Positive Crankcase Ventilation: Testing and Inspection

With the engine idling, remove the PCV valve from its attaching point. If the valve is operating properly, a hissing noise will be heard and a strong vacuum felt when a finger is placed over the valve inlet. With the engine off, the valve should rattle when it is shaken. If the valve is not operating properly it must be replaced. DO NOT ATTEMPT TO CLEAN THE OLD PCV VALVE.