Kohler Engine Blowing Oil Out Breather- Causes and Fixes

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Is your Kohler engine blowing oil out of the breather tube? Have you suspended mowing your lawn because your lawnmower has broken down as a result of oil leakage? I can understand the frustration, quite annoying when you need your engine to get working but it won’t.

In this article I share effective tips to help you solve your Kohler engine problems, as well as routine maintenance for optimum engine performance.

What Causes Oil To Push Out Of The Breather?

Whether it’s Kohler command, Kohler Magnum 28, Kohler CH 25, Kohler Courage 24, Kohler V-twin or other Kohler engines; some of the reasons why your Kohler engine might be blowing oil out of the breather include:

  • Broken Crankshaft Seal
  • Blocked Breather
  • Broken Valve Cover Gaskets
  • Blocked Filter 
  • Cracked Oil Pan
  • Broken Head Gasket
  • Fouled Cylinder.

Kohler Engine Blowing Oil Out Breather: Causes and Fixes

Here is a quick guide to help you solve your Kohler engine oil leak problems:

1. Broken Crankshaft Oil Seal

When there is a pressure from the fan and flywheel, your engine will leak oil while it is running.  You can check the location of the fan and flywheel to know if the leak is coming from there.

This is likely to occur when the engine is running, which causes the fan or flywheel to blow any oil leak around. A worn-out main crankshaft may also cause oil leak.

If the crankshaft seal is broken, it needs to be replaced. 

How to replace a broken crankshaft oil seal: Step-by-step guide to follow

  • Unscrew the front side of the lawnmower to expose the engine.
  • Remove the spark plugs.
  • Unscrew any other nuts and bolts  that fasten the engine to the mower. 
  • Pull apart the pulleys and the tabs protecting the oil seal.
  • Use compressed air to clean the dirt and debris. 
  • Using a metal object tap between the oil seals.
  • Once it becomes loose, gently pull it out.
  • Apply grease on the surface of the inner part of the new oil seal.
  • Place any anaerobic adhesive (Loctite 515) on the outer part of the seal.  
  • Put the new oil seal and hit it until it is properly aligned inside.
  • Couple back everything. 

After the replacement, the oil leakage will stop if the oil seal was the problem. Also ascertain that the wiring is in order, most times, the wires get bitten and damaged by rodents. You can use liquid tape to fix damaged wires. 

 2. Blocked Breather

Oil leakage may occur in some other places other than the breather, such as close to the cylinder walls. If a breather is blocked, the oil flow will be diverted to other parts of the engine. This blockage can be caused by the breather valve or breather gasket.

To confirm where the blockage is coming from, you can check the breather tube by blowing air through it to see if it flows freely, if not, there is a possible obstruction. For the breather gasket, check for any signs of damage.


  • Get rid of debris from the breather tube by applying compressed air. 
  • If you discover that the blockage is serious, the best thing to do is replace it with a new one. 
  • Replace the breather gasket if it is broken or damaged. 

3. Broken Valve Cover Gaskets

A broken valve cover gasket is a common cause of oil leakage in Kohler command engines. This is the reason you will notice smoke coming out of the exhaust pipe. 


Replace the valve cover gaskets, it doesn’t cost so much. 

4. Blocked Filter

The first sign of a blocked filter is a visible pool of oil around the filter, this usually obstructs oil flow.  

Why Does Oil Get Into The Filer?

  • A Clogged Positive Crankcase Ventilation (PCV) Valve: A rubber vacuum hose that serves as a vacuum release inside the engine’s crankcase is utilized to link the PCV valve to an air intake housing. 
  • Worn Piston Rings
  • When the oil passage is clogged


It is best to replace the old filter with a new one. Ensure the new one does not have any cracks or holes in it.  

5. Cracked Oil Pan

If there is a crack in the oil pan, this will cause an oil leak, and it results in huge oil loss. A regular check on this pan will go a long way to preventing the problem.


This has to be replaced if found to be leaking oil.

6. Blown Head Gasket

A good sign of broken head gasket is vapor coming out of the dipstick. This can cause oil leak problems. Oil leakage can also be caused by warped cylinder heads, changing a new valve cover gasket won’t solve the problem. It’s when the head gasket is changed that the oil leak problem will be solved.


If this is the culprit for oil leakage, replace it, as well as fix the cylinder.

7. Fouled Cylinder

Loosened nuts and bolts, faulty valve seals and head gaskets can cause a cylinder to leak oil.


  • Use a brush to clean the cylinder head. 
  • Remove the existing carbon from the valves using a 3M pad.
  • Fasten loosened bolts and replace the faulty seals and gaskets.

Kohler Engine Maintenance: Simple Steps to Follow

Below are a list of things you can do to optimize your Kohler engine’s performance:

Step 1:

  •   Regular Check on Vital Areas

Perform regular checks on Air filter, Oil (and filter), Cooling system (including the flywheel fan, cooling fins, and any radiators or oil coolers)

Step 2:

  • Recommended Fuel 


Use unleaded normal gasoline that has an octane rating of 87 or above according to the pump sticker. Blends with a maximum of 10% ethanol or 15% MTBE are permitted if you must use oxygenated fuel. Higher concentration fuels and fuels blended with methanol are not advised.


Use the same diesel fuel as is found in automobiles (EN 590 for E.U. – ASTM D975 regulation – S 15 for U.S). Other fuels could harm the engine if used. Use of impure diesel fuel or fuel and water combinations will result in major engine problems. 

Use adequate low temperature fuel typically available from fuel wholesalers when running the engine at temperatures below 0 degrees Celsius.

Step 3:

  • Use the Recommended blends of gasoline 

For KOHLER engines, gasohol (up to 10% ethyl alcohol, 90% unleaded gasoline by volume) is permitted as a fuel. Other gasoline/alcohol mixtures, such as E20 and E85, should not be utilized because they have not been approved for use in Kohler engines.

Step 4:

  • Recommended Oil 

Use the oil that is recommended for your Kohler engine type. Check your owner’s manual for specific details. 

Step 5:

  •  Use of Artificial Oil 

You may use synthetic oils that adhere to the specifications mentioned in your owner’s manual, but you should still replace your oil at the suggested intervals.

Step 6:

  • Adding Substances to Your Engine

It is NOT advised to use cleansers or additives in the fuel or oil system. Automotive engines with liquid cooling can operate at higher temperatures than those with air cooling. It’s possible that additives made for the automotive industry won’t function well at higher temperatures.

Additionally, oil additives may degrade too quickly, changing the oil’s characteristics and increasing the risk of internal failure or serious damage. 

Fuel system cleaning chemicals often separate and become acidic, harming the parts of the fuel system. However, to prevent fuel deterioration during extended periods of inactivity (more than a month), using gasoline stabilizer is advised. 


Again, some of the reasons your Kohler engine might be spewing oil out of the breather include: blocked filter, fouled cylinder, broken head gasket, etc. 

Take a careful look at your engine for signs of the possible reasons pointed out in this article and follow the step-by-step instructions provided to help you fix your Kohler engine oil leak problems.

If after trying the recommended tips in this article, the problem persists, it is advised you consult an expert to have your engine checked.