How To Stop Oil Coming Out Of Valve Cover Breather: Causes & Solution

Oil leaking from the valve cover breather can damage your car’s engine. If you notice white smoke from the valve cover breather, it means you have an oil leaking and breathing problem. This process is necessary for combustion to occur. But, it can be a bother when it happens continuously or when the oil smells heavy.

Therefore, understanding how to stop oil coming out of valve cover breather will save your engines. Nonetheless, before solving the oil leak problem, let’s learn why oil coming out from your car’s valve covers breathers and more.

Oil Coming Out Of Valve Cover Breather

Blocked Oil Breather Pipe Symptoms:

Blocked oil breather pipes can cause a variety of problems. So, it’s essential to recognize the symptoms and address them early. Here are some following signs:

High Idle

Due to the blocked crankcase breathers filter, your car’s idling speed. A blocked filter affects your car’s idling speed. When the filter is clogged, it can lead to a high idle speed. This problem is due to oil blockage or leakage in the engine. Therefore, a change in idle speed is a good indication of the issues with your car’s crankcase breather filter.

Oil Discharge

In most cases, oil leakage is another sign of a clogged filter. The filter’s primary role is to prevent debris and other contaminants from entering the engine. Because of blocked filters, there is a high chance of building pressure. Ergo, this high pressure can cause gaskets and seals to blow. As a result, your car’s engine will begin to leak oil, or you may notice oil or sludge.

Poor Engine Performance

Another notable symptom of a blocked crankcase breather filter is reduced engine performance in your vehicle. Clogged filters affect air-fuel flow, which impacts vehicle acceleration and energy. You may especially notice this problem when driving at low speeds.

However, there are several other factors that affect engine performance. That’s why it’s essential to consult your dealership, an independent professional mechanic, for a diagnosis of your vehicle.

Check the Engine Light On

As with other engine-related problems, an illuminated check engine light also shows the symptoms of a blocked breather pipe.

Reasons For Oil Coming Out Of Valve Cover Breather?

You can face oil coming out from your car’s valve cover breather for various reasons. Identifying the actual cause of this problem in your vehicle is the first step in troubleshooting. Every issue has a reason, so knowing the problem’s causes can help fix it quickly.

  • Faulty compression ring
  • Excess oil in the crankcase
  • Worn-out oil seal
  • High Pressure in Breathing.
  • Blocked PCV valve cover
Oil Coming Out Of Crankcase Breather

Here, we will discuss these causes in detail:

Excess Oil In the Crankcase

Excessive oil is one of the leading causes of valve cover oil leakage from the breather. Too much oil in your automobile will ultimately cause the liquid to foam and escape through the breather. Low or excess oil levels are unsuitable for your engine and are not recommended. Additionally, this is due to the result of oil in the valve cover, among other effects.

Worn Out Oil Seal

Worn-out or damaged oil seals are another reason for coming out of oil from breather valve covers. Worn seals allow pressure to leak, allowing oil to enter your vehicle’s inlet passage.

Faulty Compression Ring

Faulty compression rings are also the culprit of oil coming out of the crankcase breather. Besides this, defective rings allow compression to leak out. As a result, the crankcase is stressing and pushing additional oil through the breather. Likewise, the oil will enter the combustion chamber if the rings and valve guides are loose. You may also notice smoke coming from the oil cap because of this problem.

High Pressure in Breathing

High crankcase pressure is the most common reason for oil leakage from the crankcase breather. Meanwhile, cylinder gaskets, broken piston rings, and worn cylinder bores are common causes for high crankcase pressure, resulting in oil blowby. This is also the reason for 383 strokers blowing oil out of the breather.

Blocked PCV Valve Cover

Oil leaking from the PCV valve cover is also the reason for oil blowby through the crankcase breather. So, ask, “Why is my breath coming out of oil?” All of these factors will be responsible for the issue. Pay attention to these causes of valve oil leakage to figure out the most suitable solution.

Why Oil Coming Out Of Crankcase Breather Motorcycles?

There are many factors that contribute to your motorcycle crankcase breather oil. However, the most common causes are oil filter cap problems, incorrect ball seating positions, dirty breather mechanisms, and more. Let’s know more reasons in detail:

Worn or Damaged Gaskets

Gaskets seal the various parts of the engine. Thus, Gaskets can be found in the machine’s oil pan, crankcase, valve cover, or cylinder head. A worn or damaged gasket is the most common cause of motorcycle oil leakage.

Faulty Plugs

Faulty plugs are the other common cause of oil leakage. The most common plugs for leaking oil are valve cover plugs, oil drain plugs, and crankcase plugs.

Bad Piston Ring

The piston ring is a factor that helps the crankcase breathe oil out of your motorcycle. Most of the time, piston rings are worn, and oil leaks out. Furthermore, you may face this problem when the oil seal is worn out.

So, how does oil get out of your motorcycle’s crankcase breather? To fix the problem, first, you need to identify the exact problem. For example, if your motorcycle has a dirty breather mechanism, you should remove the mechanism and adequately clean it. You can also check the motorcycle oil filter cap or oil filter to fix the problem.

How To Stop Oil Coming Out Of Valve Cover Breather? Solutions

PCV valve leaking oil is easy to fix when you can identify the actual reason for the problem. Regardless, the following suggestions will help you to correct the problem of diesel engines leaking oil from breathers.

Remove Excess Oil From the Engine.

Accordingly, if too much oil is in the crankcase, drain the excess. You just need to go under the car and drain the excess oil. Hence, to do this, locate the drain plug and loosen it to drain extra oil. Meanwhile, make sure you put a pan to catch the oil and dispose of it properly.

Replace damaged Oil Seals.

Damaged oil seals aren’t good for the system. They will cause catastrophic damage all the time. So, once you notice that this is why oil comes out from your breather, replace them.

Replace Damaged Compression Rings.

Make sure your compression rings are always in good shape. During engine overhaul, it’s best to replace them. When you remove the piston ring for maximum car models, you must replace the compressor ring. Again, if you notice broken piston rings or a leaking cylinder gasket, be sure to replace those as well.

Replace the Damaged PCV Valve.

Finally, if you notice oil coming out from a damaged PCV valve, you should replace it immediately. A PCV valve replacement costs about $50 to $250. Parts cost about $20 to $50, while labor costs about $30 to $200, depending on car type and auto shop location.

Oil Coming Out Of Crankcase Breather Motorcycles

FAQ (Frequently Asked Questions)

Q. How do I prevent oil leakage from the breather?

If oil leaks through the valve cover breather, check for a blocked PCV valve. If it’s not the reason, check for engine oil overfill or check engine compression. The reason is that blowby can force oil in the inlet manifold through the breather hose.

Q. How do you relieve excessive crankcase pressure?

The PCV and VC breather system circulates air through your crankcase. This helps exit fuel and exhaust fumes in the crankcase due to blowby. Generally, if you don’t have this functionality, you may experience oil loss and excessive wear on your internals.

Check your PCV valve to make sure it’s working. Then, Check your PCV valve hoses to ensure the caps aren’t stuck. Now check a cylinder leak down to make sure your rings are sealing correctly. Don’t look for aids, but try to find the source of your problem and then fix it.

Q. Why is oil coming out of my breather pipe?

Most of the drivers face the same problem. Some drivers may notice that their breather tubes are leaking oil. There are several reasons why your breathing tube may leak oil.

  • Engine overfilling with oil
  • Too much pressure
  • Excessive engine blowby.
  • Damaged compressor ring

Final Word:

Your question was how to stop oil coming out of the valve cover breather. Here, we are trying to discuss this topic properly. On the other hand, a valve cover breather is relatively easy to maintain. But you can’t guarantee that you won’t face any problems.

Oil leakage is the most annoying problem for breathing. With our easy method, you can fix this problem quickly. Ultimately, it would help if you didn’t replace the breather tube directly because there are several reasons for oil leakage. However, inspect the situation first, identifying the exact oil blowby cause to find the accurate solution.

Read Also: Oil Coming Out of Crankcase Breather Harley


I am Engr. Z Eusuf Lubricant Specialist, Mechanical Engineer & has been working with engine lubricants for a long time and knows what makes them work best. I can help you find the right oil for your needs, and I have tips on how to keep your engine running at its best.