The PCV (Positive Crankcase Ventilation) system is one of the earliest emission-control devices used in cars and trucks. The system itself draws any leftover combustion gases from the vehicle’s crankcase (the bottom of the engine and the oil pan) and reroutes the gases back to the engine using the intake manifold. That way, the gases can be burned inside the combustion chambers rather than being allowed to escape into the air via the vehicle’s exhaust system.
Almost all positive crankcase ventilation systems have valves called PCV valves. It can be a challenge to know if that valve needs to be replaced and when it might be required.
PCV Valve: Does It Need to be Replaced?
Your vehicle’s PCV system isn’t likely to be listed in the manual as a routine maintenance item, but old valves that do not function correctly can cause many serious issues, such as emissions and performance problems. The PCV valve is designed to regulate the flow of the gases and is one of the most important aspects of the PCV system. However, it is important to note that some new vehicles do not have a PCV valve included. In this case, you do not have to worry about replacing the part because it isn’t included on the vehicle.
The PCV valve is designed to route fuel and air from the vehicle’s crankcase back into the intake manifold and on to the cylinders instead of letting it all escape into the air around you. That way, it ensures that more of the emissions from the vehicle gets reused and don’t pollute the air as much.
If the valve cannot close or open on schedule, or if any components of the system clogs up, you might experience a rougher ride, increased oil consumption, lower fuel economy, and sluggish acceleration. The trouble most consumers have is that many other issues can also cause these problems. For example, rough idling can also be caused by a bad or misfiring spark plug, and lower fuel economy can be caused by low air pressure in the tires. Therefore, the PCV valve problems can be misdiagnosed. You may want to mention the PCV valve to the mechanic if you know that you have one and ask him or her to check that first.
Sometimes, the mechanic might automatically check to ensure that the PCV valve is working correctly. If it is bad, replacing the valve can eliminate all the problems listed earlier.
Testing the PCV Valve
In most cases, the PCV valve is mounted in a grommet on your valve cover, which sits at the end of a tube or hose. One easy way to check that the PCV valve is functioning correctly is to remove the hose or tube and shake it gently. If you hear a rattling noise that sounds metallic, it’s likely working properly. If you don’t hear a sound when you shake the valves, it means that the valve might not be opening and closing the way that it should. Many times, a quick fix includes cleaning the valve to remove any buildup and help it start functioning correctly again. If that doesn’t work, you might need to replace the part.
Even if the engine doesn’t have a PCV valve, the tube or hose inside the PCV system could still get clogged up with sludge, so you may still want to have the system inspected, cleaned, and have any parts replaced as needed. That way, you can reduce problems with the vehicle, keep it running smoothly for longer, and ensure that you’re not overly polluting the air.