PCV Valve: A Details Guide

Every component and fluid in a car engine serves a specific function. Spark plugs, cylinders, pistons, and other standard auto parts are well-known to most people. The PCV system, on the other hand, isn’t something you hear much about.

While emissions equipment is critical, there are numerous additional benefits to engine health that come with it. What exactly is a PCV valve, and how do you use one? What’s the deal with PCV valves? When is a bad valve going to cause symptoms? In this article, we’ll look at the PCV system and address these concerns.

What Is the PCV System?

Positive crankcase ventilation (PCV) systems include PCV valves as an essential component. Short for crankcase ventilation system, it’s known as that. This system helps to keep the crankcase clean by removing exhaust fumes. Blowing-by occurs when fuel, oil, and exhaust vapors pass through the piston rings, resulting in the formation of these gases. Blow-by gases are produced by all internal combustion engines.

It is the goal of the PCV systems to return these gases to the intake tract, where they will be recombusted with fresh intake air. Rerouting by-product gas flows is an effective way to cut back on emissions. In fact, it was one of the first emissions control devices required by the state of California, which did so in 1961.

PCV systems became standard equipment on the majority of new cars sold in the United States within a short period of time. After that, they quickly became commonplace in automobile engines all over the world..

Emissions played a role in its quick adoption. On the other hand, PCV systems aid in engine cleanliness by removing blow-by gases before they solidify into sludge or carbon. The positive crankcase ventilation system also helps to keep oil cleaner while also extending the life of the oil.

How Does A PCV Valve Work?

How Does A PCV Valve Work

It’s critical to understand the crankcase ventilation system before learning about the PCV valve. The PCV system on the majority of engines includes the parts listed below:

  • Crankcase Breather
  • PCV Valve
  • PCV Hose

Crankcase breathers are the first step in the removal of engine crankcase blow-by gases. Air is pumped into the crankcase through the breather valve and the breather hose.

Although fresh air from the intake manifold is commonly used, the location of the crankcase breather varies by design. Whatever the case may be, the idea is to remove the blow-by gases and allow fresh air to enter the crankcase.

Intake manifold vacuum is applied directly to the engine’s crankcase via a PCV valve after that. Vacuum is used to extract blow-by gas from the crankcase, and the crankcase breather is used to replace it with fresh air to keep things running smoothly.

The positive crankcase ventilation hose returns the exhaust gases from the crankcase to the intake manifold after passing through the valve. The blow-by gases are re-combusted after they exit the furnace.

To put it another way, the PCV valve creates the vacuum necessary to remove crankcase blow-by gases. The amount of crankcase blow-by gases that enter the intake is controlled by this valve. There isn’t much to it. Even so, it’s a critical component that, if damaged, could lead to a variety of problems.

Positive Crankcase Vent Valve Location

The valve is usually found around the valve cover on the top of the engine (s). The back of the valve cover on a V engine can be either on the driver’s or the passenger’s side. A single valve cover is used on inline engines, and the PCV valve is typically located at the back.

The hose that connects the valve cover to the intake manifold should be located. The PCV hose will be on the outside, with the valve located on the inside.

The positive crankcase vent valve can be replaced without removing the valve cover on nearly all engines. Once the hose is disconnected, the valve should easily pop out. Most of the time, it’s designed to be a simple fix that anyone can do. The discussion on replacing the PCV will bring us full circle.

Bad PCV Valve Symptoms

Bad PCV Valve Symptoms

When the PCV valve on an internal combustion engine malfunctions, the following symptoms may occur:

  • Seal & gasket failures
  • Oil leaks
  • Whistling sounds
  • Sludge build-up
  • High oil consumption
  • Misfires
  • Rough idle

Even though this list isn’t all-inclusive, these are the most common signs of malfunctioning PCV valves. Also, the above-mentioned signs and symptoms aren’t always related to the PCV valve. A gasket failure and an oil leak, for example, may not be related to the PCV system at all. The PCV system is crucial, but it is important to consider the possibility that something is wrong with it.

You may experience high crankcase pressures if the valve malfunctions. Seals or gaskets can fail due to pressure when trying to let go of that pressure. However, even if the seals or gaskets don’t fail completely, oil can still seep past them and cause leaks. Whistling is another common symptom caused by high pressures in the engine.

An additional concern is blow-by gas sludge build-up, which will adhere to internals and cause deposits. Aside from being an eyesore, it has no beneficial effect on engine performance or efficiency. High oil consumption is another sign of a bad PCV valve. The mixing of blow-by gases with engine oil can also lower the quality of the oil. Erratic operation is less common, but it does occur.

Replacing the PCV Valve

Valve PCV is an item that needs to be kept in good working order. The blow-by gases that pass through them can clog the valve if they are not properly maintained. As a result, the majority of companies make it simple to remove and replace them.

An intake manifold hose is usually found running along the rear of the valve cover. Typically, the PCV valve is located inside the hose, near the point where it connects to the engine’s valve cover. Some don’t even go inside; they just attach to the hose.

Regardless, most engines’ PCV valves can be easily replaced by performing the following steps:

  1. Locate the valve
  2. Disconnect hose
  3. Twist PCV counter clockwise
  4. Check the hose, clamps, grommet, etc
    • Replace if anything looks in poor shape
  5. Install new PCV valve

The PCV costs between $10 and $30, and most do-it-yourselfers should have no problem doing it. However, there are times when working in a confined space is necessary. If you have to take your car to a mechanic, PCV replacement will cost you between $50 and $100.

When to Replace the Valve

The exact time between replacements can be determined by a wide range of factors. Some manufacturers suggest changing the valve every 30,000 miles. Others lack clear guidance, making it difficult to determine when the PCV valve should be replaced.

Replace the PCV if you’ve never had any problems with it but are now experiencing any of the symptoms of a bad valve. Some PCV valves, on the other hand, continue to work well after 100,000 miles. If your valve is in good working order, it may not be worth the time and money to replace it.. Even if your engine is new, it’s a good idea to check the positive crankcase ventilation valve.

How to Test the PCV Valve

Fortunately, most engines have an accessible positive crankcase ventilation valve. As a result, testing its functionality is a cinch. Checking the PCV valve’s health and functionality can be accomplished in a number of ways.

  • Visually inspect after valve is disconnected. You should replace the valve if you see a lot of slime, gunk, or sludge. Cleaning is an option, but since the PCV costs between $10 and $30, we believe it’s more cost-effective to simply replace it.
  • Prepare the engine by bringing it up to operating temperature and keeping it there. Disconnect the valve and place a fingernail on the end to keep it from leaking (while the hose is still attached). The positive crankcase valve should have vacuum/suction at the other end. The valve should also be visually inspected with the handle removed while it is turned off.
  • Put a piece of paper over the hole left by the oil filler cap. The paper should be sucked into the hole if the PCV valve is working properly. Try to avoid pulling the paper all the way into the oil filler by using a stiff piece of paper or other methods.

Engine Oil Catch Cans

Engine Oil Catch Cans

Topics like oil catch cans and PCV systems are becoming more popular today. As a result of the widespread adoption of direct fuel injection, this is becoming increasingly common. Recirculated blow-by can adhere to intake ports and valves because of its tendency to cling to surfaces.

Carbon build-up, a resulting deposit, is a problem on many direct-injection engines because it leads to increased emissions. Fuel is sprayed into the intake ports via port fuel injection, and any deposits are removed by the fuel. Since fuel is sprayed directly into the cylinders, direct injection does not have this advantage.

The oil catch can (OCC) is intended to be connected to the PCV system. After that, the oil vapors are filtered out, which reduces the rate at which carbon accumulates on the intake valves. To be sure, catch cans aren’t foolproof, but they do help by slowing the process down a bit. We’ll leave it at that for the time being and return to oil catch cans in a future post.

Engine PCV Summary

You don’t hear much about positive crankcase ventilation valves because they’re not commonly used. It is, however, a critical component of your engine’s emissions control system. Oil is kept clean and sludge on the engine’s internals is prevented by PCV valves, which have other advantages. When PCV systems work, they’re fantastic. However, when they malfunction or lose their effectiveness, they can be a huge pain.

Poor performance of the PCV valve can manifest in a wide range of symptoms. Continuous oil leaks, however, are a common symptom of gasket and seal failure. Pressure in the crankcase tries to escape via seals and gaskets when it builds up. As a result, they may break down and start leaking oil. Another common sign of a bad PCV system is whining.

In most cases, a PCV valve can be easily and cheaply replaced. The function of the PCV can be tested if you’re not sure if it needs to be replaced. Engine maintenance would be incomplete without checking on PCV valves, and this is especially true for diesel engines.

Positive Crankcase Ventilation FAQ’s

We’ll answer some frequently asked questions about the PCV system in the sections that follow. A few of these points may have already been made in the preceding exchanges. The following are some frequently asked questions about the PCV system.

What Does PCV stand for?

Positive crankcase ventilation is referred to as PCV. Crankcase ventilation is another name for it.

What is the Purpose of a PCV System?

Originally, they were intended to help military vessels travel through water while maintaining a tight engine seal. PCVs today, on the other hand, are designed to cut back on harmful emissions. PCV systems have the added benefit of extending the life of the engine’s oil and preventing contamination of the engine’s interior.

What are the Symptoms of a Bad PCV Valve?

Bad PCV valves can cause a wide range of symptoms. Leaking oils, whining sounds and increased consumption are some of the most common signs of seal or gasket failure. For more information, see the section above on the signs of a bad PCV valve.

How Expensive are PCV Valves?

Price ranges from $10 to $30 for a positive crankcase ventilation valve. Because it’s a low-cost piece of maintenance, don’t skip it.

How Do You Replace a Bad PCV Valve?

For the most part, engine replacement is a simple matter. Remove the old valve and replace it with the new one after finding the hose behind the valve cover. Most engines will cost between $50 and $100 in labor at a repair shop.

Up Next: Water Pump Replacement Cost

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