Among the earliest emission-control devices used in vehicles was the positive crankcase ventilation system. An intake manifold allows leftover combustion gases to be roused back into the engine from the crankcase.
Your exhaust system expels them into the atmosphere, whereas they are burned in combustion chambers. It is commonly known as the PCV valve in positive crankcase ventilation systems. However, this PCV valve may become clogged at times, causing problems with performance and emissions.
It is possible for the PCV system in an engine with or without a PCV valve to become clogged because of built-up sludge. Inspection of the entire system is therefore beneficial. Check the airflow through the valve and clean it if necessary.
Symptoms Of A Bad PCV Valve
Plastic hoses with springs are usually used for PCV valves. An engine bay fitted with plastic would wear out after ten years since it is a hot environment. You may notice various symptoms when the PCV valve fails due to its importance.
Here we will cover these signs in more detail, as well as how much the PCV valve costs and how to replace it. A bad PCV valve can cause a variety of symptoms. Here are some more detailed symptoms.
1. White/Black/Blue Smoke from the Exhaust
Oil will burn inside the engine if the PCV valve or the hoses are blocked, resulting in oil going out through the exhaust pipe if the crankcase or the hoses are blocked.
2. Increased Oil Consumption & Oil leaks
It will also push the pressure up in the cylinders and out of the gaskets if moisture is blocking the PCV valve or hoses. Check the PCV valve and the hoses if you notice several large oil leaks in your car or increased oil consumption.
3. Rough Acceleration
Your car will accelerate unevenly, regardless of the RPM, if you have a faulty PCV valve. It’s worth mentioning because it can happen if the PCV valve is misdesigned, but you probably won’t feel a broken PCV valve above idle.
If your PCV valve is wrong, you can experience misfires both at idle and during acceleration due to a faulty lean/rich mixture.
An overly lean mixture can lead to misfires if the cylinders fail to fire correctly. The fuel and the spark can be turned off if the blend is too rich. This leads to a misfire.
5. Lean/Rich Mixture
An air/fuel mixture can be wrong due to a faulty PCV valve because of the issues we discussed. It is usual for your air/fuel mixture to become lean, and you will experience the same symptoms as when your mixture is pale.
There is usually more grey/white smoke than usual, and you can often smell petrol from the car with a rich mixture.
6. High Idle RPM/Rough Idle
A broken PCV valve can cause the same symptoms as a leak in intake air because it controls the airflow between the crankcase and the intake manifold.
As a result, the idle RPM can rise too high, and other strange idle behaviors can occur, such as a very rough idle. Therefore, an excellent first step is always to check your PCV valve if you have odd idle problems.
7. Noise From The Engine
You can tell when something isn’t working correctly when you hear a strange sound while driving.
An engine with a bad PCV valve will often make a hissing, whistling, or whining sound or even moan lowly. It is most likely that a leak in the PVC hose causes the hissing sound.
Methods For Testing Your PCV Valve
Your dashboard’s check engine light will illuminate when you have a bad PCV valve. However, in the engine control module, a trouble code shows up when the engine light comes on.
An OBD2 scanner is required to read the engine control unit’s trouble code. It is possible for older cars without an electronically controlled engine not to show this symptom if they have PCV valves fitted. An end-connected hose or tube holds the PCV valve, usually mounted in a grommet on a valve cover.
Although it isn’t listed in a vehicle’s maintenance schedule, a PCV system should be inspected periodically to ensure it functions correctly. This is especially important if engine performance has declined.
Give It A Good Shake
You can check a PCV valve’s functionality by shaking it after removing it from the tube or hose. There is a good chance it is in good working condition if a metallic rattling noise is heard.
A valve that doesn’t open and close as it should is likely damaged. If you shake it, there is no sound. Depending on the situation, you may be able to clean or replace the valve to restore its function.
Check Engine Light Warning
When the vapors in the crankcase aren’t allowed to flow into the combustion chambers, a clogged hose, PCV system, or idle valve can lead to increased oil consumption.
Oil can pass through seals and gaskets under that additional pressure. When the valve is stuck in the open position, or there is a leak in the system, too much air will enter the engine, causing the air-fuel mixture to be thrown off, and the check engine light will likely illuminate.
Check For Moisture Contamination
Ensure the PCV valve or hose has no cloudy or milky film, as this indicates moisture contamination. You’ll need to replace the valve if the system is contaminated with moisture.
Therefore, moisture in your PCV valve may indicate other issues, so replacing the valve alone won’t solve your problem, but changing the oil will. A failure to do so will result in symptoms returning soon.
A vehicle that is mainly driven on short trips, particularly under ten miles, will typically have more moisture buildup, leading to more frequent oil changes. As well as oil changes, combine your errands so you can drive for more prolonged periods every time you start the engine.
Despite that, if the moisture buildup problem does not go away, other engine problems are likely causing the moisture buildup. Oil filters get contaminated with moisture since moisture is a liquid. Oil needs to be changed more often because of this.
Common Trouble Codes Associated with the PCV Valve
A faulty PCV valve can cause some standard trouble codes. You may need to check your PCV valve if you experience any of these engine control unit trouble codes.
Even though you see these trouble codes, there is no guarantee that the PCV valve is faulty. You should always troubleshoot before replacing any parts if these codes occur.
When Should You Replace The PCV Valve?
It is possible to have a rough idle, sluggish acceleration, or increased oil consumption if the valve does not open and close on schedule.
Problems with the PCV valve are often misdiagnosed because bad spark plugs cause rough idling. It may be possible to eliminate the problems outlined above by replacing your PCV valve if your PCV valve is bad.
How Much Does It Cost To Replace A PCV Valve?
Costs vary depending on the car model and labor costs, but on average, it’s $50 to $250. It usually costs between $20 and $50 for a PCV valve. Mechanic shops charge between $30 and $200 for labor.
Several factors can affect the cost of replacing faulty PCV valves, such as the engine and the car you have. For a new PCV valve, you should expect a price of around $20-50.
However, if your car has a valve under the manifold, you may have difficulty replacing it if you are not knowledgeable about it. According to the type of car and the location, a mechanic can expect to charge $30-200 to replace this part.
How Often Should The PCV Valve Be Changed?
PCV valves are not scheduled for replacement regularly. Over 100,000 miles is the typical lifespan for a PCV valve. However, it is relatively cheap and easy to replace the PCV valve, so if your car is a couple of years old, you might consider doing so.
Is A PCV Valve Open At Idle?
The PCV valve should remain closed or semi-closed during idle to prevent too much vacuum from building up inside the crankcase. The PCV valve opens fully when the throttle is pressed a little, allowing crankcase gases to escape.
Is The PCV Valve Necessary?
There is a possibility that the crankcase can experience too much underpressure during idle and too much overpressure during turbo boost without the PCV valve. As well as improving fuel efficiency, the PCV valve can recycle unburned fuel vapor.
Can You Clean The PCV Valve?
It is possible to clean your PCV valve if it is clogged. A PCV valve’s spring mechanism usually becomes old and worn out over time. To avoid future problems, replacing PCV valves is recommended, even though you can clean them.
How Long Is The PCV Valve Lifespan?
In terms of PCV valve lifespan, there is no universal agreement. Many car manufacturers do not strictly enforce PCV system maintenance. Manufacturers recommend PCV servicing between 20,000 and 90,000 miles, depending on the model.
It can last long, depending on the conditions it’s subjected to. It is usually recommended to replace a PCV valve at the first ignition tune-up after 80,000 miles. However, the failure of some can occur much earlier. If the vehicle is subject to extreme conditions, it may need to be replaced after 30,000 miles.
The Bottom Line
The good news is that you can test and replace this valve pretty easily. A new valve could make your vehicle run much smoother, regardless of whether you return it yourself or hire someone.
Generally, the PCV valves can be replaced quickly and should only take a few minutes if you have an older car. A replacement under the intake could take over 3 hours on newer cars. Accessing the PCV valve sometimes requires removing the intake; fortunately, it is not very common.