Back to all

PCV Valve: What Is It?

November 9, 2025

Most Louisville drivers know something about preventive maintenance on a vehicle. We know we should routinely replace the oil and wiper blades and other fluids. But have you heard of a PCV valve ? This little car part needs to be replaced regularly or it can cause some serious problems in your vehicle engine.

PCV stands for Positive Crankcase Ventilation. The crankcase holds your motor oil and is located at the bottom of your engine.

When fuel is burned in your engine, it produces waste gases that are mostly vented out through your exhaust system. But some of these gases push their way past the pistons and into the crankcase. There, these gases can mix with motor oil to produce oil sludge, which can damage vehicle engine parts through corrosion and by clogging engine passages. Louisville vehicle owners should be advised that if the engine is running at high speeds, these gases can also cause pressure inside the crankcase to build up. This pressure, in turn, can blow gaskets and damage seals, leading to oil leaks.

The waste gases that leave the engine are comprised of about 70% unburned fuel. They used to be vented off the crankcase into the atmosphere. But starting in 1964, laws mandated that these gases be recaptured. Manufacturers began installing PCV systems, which recycled the gases into the air intake system where they could be mixed with fuel and sent to the engine to be burned.

The PCV valve is a one-way valve attached to the crankcase. Waste gases exit the crankcase through the valve but cannot enter.

Over time, the waste gases leave deposits on the PCV valve that can gum it up. So it needs to be replaced occasionally. This is an inexpensive part of preventive maintenance that is often overlooked, but which can have very expensive consequences. It's good auto advice to keep this little valve clean and working well.

In order to maintain efficient circulation, the PCV system also has a breather tube that allows clean air to enter the crankcase. This air is usually filtered through the engine air filter. But some vehicles have a separate air filter for the breather tube called the breather element. If this is the case with your vehicle, proper maintenance of the PCV will include replacing this element. To find out whether your vehicle has this type of PCV system, check your owner's manual or ask your service advisor at Car Fix Louisville.

The PCV system reduces harmful vehicle emissions. The maintenance it requires is simple and inexpensive at Car Fix Louisville. A fouled or damaged PCV system can lead to serious engine damage for Louisville drivers.

Let's all learn to practice good car care. It's good for our wallets, and it's good for our KY environment.

Car Fix Louisville
5411 New Cut Road
Louisville, KY 40214
5023652323

Need Service?

Request a Quote

More articles from Car Fix Louisville - Formerly Eagle Tire & Auto Center

Automotive Tips from Car Fix Louisville: Where Should New Tires Be Placed

March 15, 2026

When Louisville drivers need to replace tires, they need to know how many they should get and on which axle they should be placed. Replacing a damaged tire may leave you with three others with significant wear, which could affect your traction control, stability control and anti-lock brake system... More

How Does Car Fix Louisville Know What to Recommend?

March 8, 2026

When you drop your vehicle off at Car Fix Louisville in Louisville, they don't just poke around under your hood looking for stuff to do. Car Fix Louisville professionals have lists and procedures they follow for different types of service. First of all, your Louisville service center will note th... More

Don?t Meddle with the Pedal (Brake Caliper Replacement)

March 1, 2026

If you drive a newer vehicle, chances are it has disc brakes, and one of the components of that type of brake is called a brake caliper. The caliper allows the pressure from your foot on the brake pedal to eventually move brake pads against discs in your wheels, which then slow and stop your veh... More