The PCV valve (Positive Crankcase Ventilation valve) is a uni-directional valve that continually evacuates gases from inside your automobile engine's crankcase. The PCV valve is a small, simple engine component, but it is vital to your engine's functioning properly. Though it is rather small, the PCV valve is located in generally the same place in most car's engines, so finding it under your hood should not be too difficult.
Pop the hood of your automobile and prop it up with the prop shaft. If the engine has just been running, it will be extremely hot. Use work gloves for protection.
Locate the main engine encasement in your car. It is the largest component under the hood and will typically have the make and model of your car imprinted on top of it. It houses the large, cylindrical pistons of your car's engine.
Locate the crankcase. Typically, just to one side of the main engine encasement lies the crankcase--a long rectangular component with several tubes running from it to the main encasement, and usually a black or silver cylindrical shaft at its top.
Locate the PVC valve. The PVC valve is a small valve usually in the center of the crankcase, connecting it to the gasoline intake manifold of the main engine encasement. (If you locate the breather connection, usually a thick black rubber tube, the PVC valve is roughly opposite this location along the crankcase.) The PVC valve is an L-shaped valve. The top end is slender and simple; on the bottom end there is usually a fatter cylindrical attachment.
