To find the positive crankcase ventilation, or PCV, valve, open the hood of your car, and locate the crankcase. Find the fuel-intake manifold on the engine, and look for a black tube that connects it to the crankcase. Pull the tube away from the crankcase to expose the PCV valve.
Although the PCV valve is always located on the exterior of the crankcase, the specific location varies by vehicle. If you do not see it on the top surface, run your hand around and under the crankcase until you find a rubber hose. You may need to remove other engine components to access the valve for repairs.
Some PCV valves feature an L-shaped casing that connects to the thick rubber tube. Others have a vertical casing that extends straight out from the case. No matter which configuration your vehicle uses, the valve is usually thicker on the end that connects to the crankcase; the wide section prevents leaks around the opening.
Many PCV valves feature a simple plug-in design, while others have threaded ends that twist into place. Most valves can be removed by hand for repair or replacement. If your valve has a small metal clip, you must release it before you remove the valve.