The PCV Valve Definition - What Is A PCV Valve?

The PCV Valve Definition – What Is A PCV Valve? Any portion or fluid within an automobile engine has a specific purpose. Many people are familiar with commonplace items such as spark plugs, cylinders, pistons, and so on. Unfortunately, the PCV system is not an often discussed topic. It is critical emissions equipment, but it also has various other advantages for engine health. So, what exactly is a PCV valve? How do PCV valves function? What are the signs of a faulty valve? In this essay, we will look at the PCV system, answer these questions, and provide further information.

The PCV Valve Definition - What Is A PCV Valve

Table of Contents

What Exactly Is the PCV System?

PCV valves are an essential component of the positive crankcase ventilation (PCV) system. Crankcase ventilation system is another name for it. This system purges the crankcase of undesirable gases. These gases are produced as a result of blow-by, which occurs when fuel, lubricant, and exhaust vapors pass through the piston rings. Blow-by gases are produced by all internal combustion engines.

The PCV system’s objective is to reroute these gases to the intake tract, where they will mix with new intake air and re-enter the combustion process. Rerouting blow-by gases aids in the reduction of emissions. It was one of the first emission control devices, with California mandating them in 1961. After a few years, most new cars in the United States included a PCV system. They immediately became the global standard for car engines.

Emissions had a role in its quick introduction. PCV systems, on the other hand, help keep engine internals clean by eliminating blow-by gases before they create sludge or carbon buildup. Furthermore, the positive crankcase ventilation system keeps oil cleaner and extends oil life.

How Does A PCV Valve Operate?

To understand how the PCV valve works, first learn about the crankcase ventilation system. For the PCV system, most engines use the following components:

Breather for Crankcase
The PCV Valve
Hose for PCV

Crankcase breathers initiate the removal of undesired blow-by gases from the engine’s crankcase. Fresh air is routed into the crankcase via the breather and breather pipe. Many crankcase breathers draw fresh air directly from the intake manifold, however the position differs depending on the design. Nonetheless, the concept is that as the blow-by gases are eliminated, fresh air must enter the crankcase.

The PCV valve then directs intake manifold vacuum to the engine’s crankcase. The vacuum removes blow-by gases from the crankcase, and the crankcase breather replaces them with fresh air. Crankcase gases depart the valve and return to the intake manifold via the positive crankcase ventilation hose. The blow-by gases are then recycled via the combustion process.

The PCV valve, in essence, creates the necessary vacuum to eliminate blow-by gases from the crankcase. It really regulates the amount of crankcase blow-by gases that enter the intake. Nothing too difficult. Nonetheless, it is a critical component that can create a slew of problems if it fails.

Crankcase That Works Placement of the Vent Valve

The valve is usually positioned near the top of the engine, near the valve cover (s). It could be on the back of either the driver or passenger side valve cover on a V engine. Inline engines have only one valve cover, and the PCV valve is typically located in the back. In any case, search for a hose connecting the valve cover to the intake manifold. That is normally the PCV hose, with the valve inside.

On almost all engines, the positive crankcase vent valve can be replaced without removing the valve cover. The hose should simply pop off, allowing the valve to be removed. It’s usually intended to be a simple, straightforward repair. We’ll return to this in the section on replacing the PCV.

Signs of a Faulty PCV Valve

The following are symptoms of a faulty PCV valve on an internal combustion engine:

Failures of seals and gaskets
Oil spills
Whistling noises
Sludge accumulation
Excessive oil usage
Misfires
Idle time

This is not an exhaustive list, but these are some of the most common symptoms of faulty PCV valves. The symptoms listed above may not usually point to the PCV valve. A gasket failure and oil leak, for example, could be a separate issue unrelated to the PCV system. Yet, considering the importance of the PCV system, it is critical to evaluate the likelihood of a problem.

When the valve breaks, excessive crankcase pressures may occur. The pressure will try to escape elsewhere, causing seals or gaskets to fail as a result of the pressure. Oil leaks may then occur, or oil may just seep past the seals or gaskets, even if they do not completely break. Excessive pressures also create engine whistling, which is one of the most common symptoms.

Another worry is sludge buildup, which occurs when blow-by gases attach to internals and cause deposits. It’s an unsightly look that has no bearing on engine function or performance. High oil consumption is another sign of a faulty PCV valve. It can also degrade oil quality by allowing blow-by gases to mingle with engine oil. Misfires and harsh idle are less common, but they do occur on occasion.

Changing the PCV Valve

PCV valves are categorized as maintenance items. They are, after all, vulnerable to a high volume of blow-by gases that can clog the valve. As a result, most manufacturers make it simple to remove and replace them. Likewise, a hose running to the intake manifold is frequently visible on the rear of the valve cover. The PCV valve will be located inside that hose, usually at the connection to the valve cover. Rather than resting within, some merely attach to the pipe.

In any case, changing the PCV valve on most engines is as simple as this:

Find the valve.
Remove the hose.
PCV should be twisted counterclockwise.
Examine the hose, clamps, grommet, and so forth.
If something appears to be in poor condition, replace it.
Replace the PCV valve.

The valve typically costs between $10 and $30, and most do-it-yourselfers should have no trouble replacing the PCV. Nonetheless, it can be a challenging environment to work in at times. If you wind yourself in a repair shop, PCV replacement can cost between $50 and $100 in labor.

When Should the Valve Be Replaced?

Many distinct factors can influence the exact replacement interval. Some manufacturers advise replacing the valve every 30,000 miles. Others lack specific advice, making it difficult to determine when to replace the PCV valve.

If you’re experiencing any of the signs of a faulty PCV and know the valve has never been changed, now might be an excellent time to do so. Nonetheless, some PCV valves continue to operate after 100,000 miles. If your valve is in good operating order, it may not be worth the time and money. It’s still a good idea to run the positive crankcase ventilation valve test, especially if your engine is old and has a lot of miles on it.

How to Perform a PCV Valve Test

On most engines, the positive crankcase ventilation valve is easily accessible. This makes testing its functionality simple. Among the ways for determining the health and operation of the PCV valve are:

Disconnect the valve and inspect it visually. If you observe a buildup of slime/gunk/sludge, it’s time to replace the valve. Cleaning is a possibility, however since the PCV is just $10-30, we believe it is usually more cost effective to simply replace it.
Get the engine up to working temperature. Remove the valve and cover the end with your finger (while the hose is still attached). The vacuum/suction should be felt from the end of the positive crankcase valve. As the valve is turned off, visually inspect it.
Remove the oil filler cap and cover the hole with a piece of paper. The paper should be sucked against the hole if the PCV valve is working properly. To stop the paper being pushed all the way into the oil filler orifice, use a strong sheet of paper or take other precautions.

Cans for catching engine oil

Oil catch cans and PCV system discussions are becoming more popular in today’s environment. This is due to the fact that many engines are transitioning to direct fuel injection. Blow-by can stick to intake ports and valves when it is recirculated into the intake manifold. It then generates carbon deposits, which are an issue in many direct injection engines. Port fuel injection sprays gasoline into the intake ports, removing any deposits. Direct injection, on the other hand, does not have the advantage because fuel is poured directly into the cylinders.

Anyway, the oil collect can (OCC) is designed to be attached to the PCV system. It then filters the oil vapors to decrease the carbon buildup on the intake valves. Catch cans aren’t completely effective, but they do help to slow down the process. We’ll leave it there for now and return in the near future with a more in-depth post about oil catch cans.

PCV Summary for Engine

Positive crankcase ventilation valves aren’t a topic that comes up very often. Yet, it is a critical component of your engine’s emissions control systems. Further advantages of PCV valves include keeping oil clean and minimizing sludge buildup on engine internals. PCV systems are fantastic when they work, but they can generate a slew of problems when they fail or lose effectiveness.

The symptoms of a faulty PCV valve are quite numerous. Continuous oil leaks produced by gasket and seal failures, on the other hand, are a prevalent symptom. As pressure builds up inside the crankcase, it attempts to escape via seals and gaskets. As a result, they may fail and leak oil. Whining is another common sign of a faulty PCV system.

Thankfully, a PCV valve is usually affordable and simple to replace. If you are undecided whether or not to replace your PCV, there are a several methods for verifying its function. In essence, PCV valves are an essential component of engine maintenance and should not be disregarded.

FAQs on Positive Crankcase Ventilation

These are some frequently asked questions about the PCV system. Part of this may be redundant to previous conversations. Still, here are some frequently asked questions about the PCV system.

What is the abbreviation for PCV?

PCV is an abbreviation for positive crankcase ventilation. Crankcase ventilation is another name for it.

What is the Function of a PCV System?

They were originally intended to allow military craft to travel through water in order to maintain a tight seal on the engine. The goal of a PCV nowadays, however, is to reduce hazardous emissions. PCV systems also extend the life of the engine’s oil and keep the engine’s internals clean.

What are the Signs of a Faulty PCV Valve?

There are numerous potential indications of faulty PCV valves. The most prevalent signs are seal or gasket failures, oil leaks, whining sounds, and increased oil consumption. For further information, see the section on malfunctioning PCV valve symptoms above.