Kohler Engine Blowing Oil Out Breather: How to Fix

Kohler engines are a popular choice for many outdoor power equipment applications, such as, lawnmowers, generators, and pressure washers due to their durability and reliability.

However, even the most well-maintained Kohler engine can develop problems. And blowing oil out of the breather is one of them.

A kohler engine blowing oil out breather due to a variety of reasons. Starting from worn or damaged piston rings to incorrect breather tube installation.

A full scenario of the Kohler engine blowing oil out the breather and what its effects are on your mower is discussed in this article. Keep on reading to find out!

Kohler Engine Blowing Oil Out Breather

Why Is Kohler Engine Blowing Oil Out Breather?

The breather is a small component located on the engine’s valve cover. Its primary function is to relieve pressure within the engine.

If the engine is operating properly, the breather should only release air. However, if there is a problem with the engine, oil may leak from the breather.

Here are some of the symptoms of Kohler engine blowing oil out the breather:

  • Blue or White Smoke
  • Reduced Oil Pressure
  • Oil Coming Out
  • Engine Overheating
  • Rough Running

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Reasons of Kohler Engine Blowing Oil Out Breather

Here are some of the possible causes of a Kohler engine blowing oil out of the breather:

1. Overfilling the Engine with Oil

Overfilling the Engine with Oil
Overfilling the Engine with Oil

The crankcase can become pressurized when the engine is overfilled with oil. This causes oil to be forced out of the breather.


Check the oil level on the dipstick. If the oil level is above the maximum level indicated on the dipstick, the engine is overfilled.

Now, to fix overfilled oil, drain the excess oil from the engine.

2. Worn Piston Rings

When the piston rings on the engine are worn, oil can bypass the rings and enter the combustion chamber. This can result in excessive crankcase pressure, forcing oil out of the breather.


Do a compression test on each cylinder to identify the problem. Compression values for a healthy engine should be within 10% of one another.

Much lower readings from one or more cylinders could be a symptom of worn piston rings.

You must change the worn piston rings to fix the issue.

3. Clogged Breather

The breather can get clogged by means of dirt, oil sludge and debris over time. A clogged breather can prevent air from flowing into and out of the engine.

This can cause pressure to build up inside the crankcase, forcing oil out of the breather.


The breather is a small tube or hose that connects to the engine’s crankcase. Check the breather and ensure it is clean and free of obstructions.

Use a suitable solvent or degreaser to give clogged oil channels a thorough cleaning.

4. Faulty PCV Valve

The Positive Crankcase Ventilation (PCV) valve regulates the flow of air into and out of the crankcase of the engine. If the PCV valve fails, pressure can build up in the crankcase, causing oil to be forced out of the breather.


To check the valve’s functionality, blow into one end while covering the other with your finger. You should feel resistance and hear a clicking sound. The valve may be broken if it doesn’t click or feels slack.

Look for signs of damage or leaks in the hoses and connectors that are connected to the PCV valve. Ensure that the hoses are securely fastened and connected.

You must replace a damaged PCV valve in order to fix it.

5. Blown Head Gasket

When the engine’s head gasket fails, oil leaks into the combustion chamber. This causes excessive pressure in the crankcase and oil to be forced out of the breather.


If a damaged head gasket is the cause, it needs to be changed. The cylinder head of the engine must be taken apart and the gasket should be changed. It is advised to speak with a qualified mechanic or a certified Kohler service technician.

6. Diagnosis of Faulty Components

Damaged or broken engine parts, including bearings or crankshaft seals, can increase oil consumption and crankcase pressure. This can result in oil blowing out the breather.

A Kohler engine must be partially disassembled to check the bearings and crankshaft. It is a bit challenging and time-consuming.

From the engine block, take out the oil pan, connecting rods, and pistons. Visually check the item for wear or damage indications such as scoring, nicks, or discoloration.

Measure the internal diameter of the bearings and the diameter of the crankshaft journals with a micrometer or dial bore gauge.


Inspect the engine components for wear or damage and replace as necessary.

7. Diagnosis of Oil Leakage

Oil leakage into the combustion chamber may be caused by worn valve guides or seals in an engine with overhead valves. Remove the valve cover and check the valve guides and seals for wear or damage.


Tighten loose components, replace gaskets, valves, pistons, rings and seals.

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Kohler Engine Blowing Oil Out Breather – FAQs

What is the cost of fixing the Kohler Engine blowing out the breather?

The cost is small if the problem is a blocked breather or a broken breather tube, often costing between $50 and $150 for materials and labor. The price may be much greater if the problem is more complicated, such as with worn piston rings or harmed valve seals. The price ranges from $500 to $2,000 or more.

How can I prevent my Kohler engine from blowing oil out the breather?

Maintain regular checkups and use high-quality oil.

Can I still use my Kohler engine if it’s blowing oil out the breather?

It is not advised to keep using a Kohler engine that is blowing oil out the breather. Blowing oil out the breather may be a warning of underlying engine problems that, if ignored, might result in significant damage.

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