Functions of the PCV Valve in a BMW

BMWs are built with safety and performance in mind, with a powerful engine under the hood, but they still require proper, scheduled maintenance. After driving your BMW for an extended period of time, you may need to have the PCV valve replaced. Below you will find information about the PCV system, the PCV valve, and what signs to look for if it has failed.

How the PCV System Works

The PCV system is an acronym for the Positive Crankcase Ventilation system, and it is ultimately responsible for moving clean air through your BMW’s engine. The way it works is that there is an inlet hose that is connected to a filtered air source. This filtered air supply is what is carried throughout the engine. Depending on the make and model of your BMW, there is a separate inlet hose that will clean the air that is incoming from only the PCV system. As the filtered air is circulated through the engine, it picks up fumes and vapors that require extraction. This filtered air then drops the fumes and vapors off in the manifold via a connecting hose. The air circulating through the PCV system helps to ensure that the fumes are drawn away from the crankcase and burned in the engine for use. The PCV system also creates a slight vacuum while the air is circulating, which helps to relieve any pressure that could build. This negative pressure is also beneficial because it can prevent oil leaks.

The Function of the PCV Valve

With all this being said, the PCV valve is the component that regulates the amount of airflow. This is important because there needs to be the correct amount of airflow constantly flowing through the engine in order for the fumes and vapors to be picked up. The proper amount of airflow is also crucial because there needs to be constant negative pressure. As mentioned above, the negative pressure in the system helps to prevent oil leaks. The PCV valve is located at the point in the system where the fumes are being drawn out. If the vacuum that is created is too high, then there is the potential of oil being drawn out too soon. So in order to prevent this, the PCV valve helps to regulate the vacuum pressure based on the engine load and speed.

For example, while your BMW is idling, it requires less of an air and fuel mixture to power it, so the PCV valve will decrease the amount of air flowing through the system in order to prevent the mixture from becoming lean. One the other side of things, when you are accelerating, the air and fuel mixture are operating at a higher speed, so the valve is going to be less involved in order to ensure that the airspeed is maintained.

Signs and Symptoms of a Failed PCV Valve

The PCV valve is an important part of your BMW’s engine operation, so it would be beneficial to know the signs and symptoms of a bad or failing PCV valve. These signs will indicate to you when there might be something wrong with the PCV valve that needs addressing.

The first indication is that the check engine light will illuminate. The light will be illuminated if the PCV valve is stuck in either an open or closed position. Another indication of a failed PCV valve is that there are engine leaks and failed oil seals and gaskets. If the pressure deviates from what is optimal for your BMW, then the oil seals and gaskets will fail, causing engine oil to leak out. A third sign that you should be aware of is the engine surging and black smoke coming from the engine. This can be due to sludge and moisture that can build up in the system once the PCV valve has failed.

Servicing your BMW

If you have noticed any of the above-mentioned signs or symptoms, then it is time to bring your BMW in for servicing. At Hayes European, we will take very good care of your and your BMW. We are conveniently accessible from the areas of Santa Cruz, Aptos, Soquel, and Capitola, CA. You will easily be able to make an appointment to see one of our trained and certified technicians.

At the appointment, our technicians will use the latest and most up-to-date equipment in order to diagnose if the PCV valve has indeed failed. If the part needs to be replaced, we will order only the best that is available through the manufacturer but at less cost than that of a dealership. Through this method of trusted service, we are able to build a lasting relationship with you. We will repair your BMW quickly so you can be back on the road driving safely with confidence in your car.