What is a PCV Valve in a Car?
1 Answers
PCV valve, which stands for Positive Crankcase Ventilation, is an active ventilation control system. It is a metering control valve installed between the engine crankcase ventilation system and the intake system. The PCV valve is controlled by vacuum and regulates the flow of oil fumes from the crankcase ventilation system into the intake system. The flow rate is higher when the engine is running at high speeds compared to low speeds. Additionally, the PCV valve should cut off ventilation to prevent crankcase explosions in the event of engine backfire. At the end of the engine's combustion process, some unburned air-fuel mixture leaks into the crankcase under high pressure through the piston rings. This leakage is referred to as "blow-by" in the industry. If not removed, these blow-by gases can escape into the atmosphere, causing pollution, and can also dilute the engine oil, leading to premature oil degradation and accelerated engine wear. The PCV system mainly consists of ventilation hoses and the PCV valve. One hose typically connects the air cleaner to the valve cover, while the other connects the PCV valve to the intake manifold. Methods to determine if the PCV valve is functioning properly: With the engine idling, clamp the hose between the PCV valve and the vacuum source. If the engine speed drops by 50r/min or more, it is normal. Otherwise, check for blockages in the PCV valve and hoses. Additionally, remove the PCV valve from the valve cover and place your finger over the valve's intake port. If you feel strong vacuum suction, it is functioning normally.
