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Why Oil Is Leaking Through Filter in Lawn Mower

Lawn mowers are machines that cut grass. A lawn mower is a machine that is used to cut grass and weeds in the landscape, typically on private property. They are tools that help us to clean up and maintain the lawn.

They come in different types and sizes, depending on their intended purpose. Most of the lawn mowers have metal blades and are powered by an engine to propel them through the grass.

Sometimes these machines get problems. Such problem is oil leaking through the filter of the mower. Oil leaking in lawn mower is a common problem for many homeowners.

While the oil dripping onto the ground is not easy to remove, there are some precautionary measures that can be taken to prevent it. In this article we’ll be discussing about the issue and the possible fixes regarding the issue.

Oil leaking through filter in lawn mower
Oil leaking through filter in lawn mower

Reasons behind oil leaking

Many homeowners are not aware of the reasons behind oil leaking in their lawnmower. Some of these reasons include an oily filter, overfilled crankcase, and an oversoaked air filter.

These are major reasons why oil leaks occur in your mower, and they can be easily prevented with proper maintenance. Some of the major internal problem can also cause this issue.

Oily Filters

One of the most important parts of a lawnmower engine is the filter. The filter traps dirt and particles from being mixed with gasoline and combusting.

If the filter gets clogged with oil, it can cause oil to leak through the filter and into your engine. The oil filter on the lawn mower is trapping dirt and mowing grass particles.

This eventually leads to a buildup of oil in the engine and potentially causes a fire. An oily filter can also cause inconsistencies in your engine, which can result in poor performance, as well as cause damage to the mower itself.

It is important for you to keep this debris out of your engine’s cylinders by periodically changing your filter. It’s not easy to find a replacement for an old lawnmower engine so it’s important that you keep an eye on your mower’s filter.

You should know how to change your lawnmower oil every year and make sure that your mower is in good shape.

Incorrect Procedures

Turning the mower over the wrong way is dangerous for both the operator and for the machine itself. There are several reasons why this might happen, one of which is when blades from underneath the mower deck can cause oil to leak from the filter.

The process of turning the mower over the wrong way was to turn the mower with the air filter down. This created a situation where oil leaked through the filter and onto blades underneath.

The oil leaks through the filter causing a mess for your lawn and can damage other parts of your machine as well. It’s important to keep your mower in good working order by taking care of it when you use it.

Overfilled Crankcase

Crankcase is the housing where an engine’s crankshaft is located and contains the entire crank mechanism. A crankcase is made up of a number of parts. It also has a complex cast part which includes pistons, cylinders, and connecting rods.

A crankcase is necessary for any engine to work properly. The crankcase creates the pressure needed for oil to flow through each cylinder and cooling channels are required for proper vehicle operation.

The crankcase is typically small and can be easily overfilled by a small amount of oil. When this happens, the excess oil will drop down into the filter or breather tube and cause damage.

Oil leak from crankcase to breather tube
Oil leak from crankcase to breather tube

Oil enters the engine through the carburetor, travels through the other internal components and ends up in the air filter. Oil can cause damage to some of other components if not cleaned up regularly.

Add a little oil to the crankcase, then check the oil dipstick and add more if needed.

Oversoaked Air Filter

Oversaturated air filter with oil is very dangerous to the mower. Oil can leak out of the air filter and clogs the engine. This process will cause a lot of damage to the lawn mower and the engine.

 Oversoaked Air Filter leaking oil
Oversoaked Air Filter leaking oil

The best option is to replace the air filter, which will stop oil from leaking through it and the lawn mower. The oil that leaks out of the air filter ends up coating other parts on your lawnmower like the engine, carburetor, etc.

So, if you do not replace your filter often enough, your lawnmower will eventually break down because too much oil is being sucked into it.

To avoid oil leaking through an oversoaked air filter, make sure you change them once per season or when they get clogged with dirt or debris. Also, you must clean the carburetor as needed.

Internal Problems

Sometimes oil leak occurs because the internal problems caused by worn parts, blown head gaskets, and damaged cylinders.  Internal problems cause oil to leak through filters in lawn mowers.

Internal problem in lawn mower
Internal problem in lawn mower

If you experience these problems, contact a small-engine specialist to fix these issues for you before they become more serious. They might need more expensive repairs such as a blown head gasket or damaged cylinder worn cylinder rings.

Sometimes you might need a small-engine specialist to repair a lawn mower with a faulty oil filter.

If you are looking for a small engine specialist to help with your lawn mower, make sure they use quality oil and filters and that they understand your equipment before they start servicing it.

The engine needed new cylinder rings and a new gasket for oil from entering properly into the engine again.

Tipped Lawnmower

Most lawnmowers come with a filter that prevents dirt into the engine. When the lawnmower is tipped over, oil can leak through the filter.

A tipped lawnmower can cause oil to leak into the engine and air intake when it is running. Filters may also become clogged with debris that builds up over time.

This can lead to a variety of issues with engine performance, breakdowns, and emissions issues. This causes engine misfiring and damage to other parts as well.

In this case, it can cause oil to leak from the crankcase into the breather tube. Tipping over a lawnmower can cause oil to flow towards the carburetor which can cause significant problem by clogging up oil in air filter.

To prevent this from happening, always be mindful to keep your lawnmower in good condition and clean by checking it after every use for signs of wear such as dents or dings.


Oil leaking in a lawn mower due to any of these problems is a common issue faced by homeowners worldwide. To prevent this issue, it is important that you follow proper maintenance procedures before using your mower for its intended purpose.

The problems that you need to fix are not as easy as it may seem. Sometimes, the solution can be even more complicated and time-consuming than the problem itself. Then you need professional help to fix this.

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