Lawn Mower Air Filter Soaked in Oil? Causes + Fixes

Air filters are meant to trap dirt and debris from air before it enters the engine through the carburetor. Oil dripping on your lawn mower air filter can impair its ability to protect the engine from long term damages. Let’s look at why your lawn mower air filter is soaked in oil and how to fix the problem.

A filter oversaturated with oil will not effectively clean the air as required. The excess oil will also leak into the carburetor and gum up its internal jets and needle valves. For this reasons, you may experience a problem starting your lawn mower, reduced engine power and eventual total breakdown.

Why is my Lawn Mower Air Filter Soaked in Oil?

Oil-soaked air filter is a serious lawn mower problem that should be fixed urgently. Understanding what cause this to happen should be the first step in providing the solution to the problem. I have identified a number of reasons why a lawn mower air filter is soaked in oil. They include the following:

Tilting your lawn mower

Tilting a lawn mower at an angle more than 15 degrees with its carburetor facing downward will make oil to escape from the crankcase into the other parts of the engine including air filters. In most cases, this is also a reason why your lawn mower is smoking white or blue.

In many cases we tilt our lawn mowers when we want to clean the bottom of the mowing deck, sharpen lawn mower blades or when cutting grass on slopes and slanted grounds. Tipping your lawn mower with the carburetor facing on the high side can help in preventing oil spill on the air filter.

Overfilled Oil Crankcase

Overfilled crankcase will push the excess oil to spill into any direction. Most engine parts below the crankcase will get soaked as the oil also moves into the carburetor and out through the air filter. When adding engine oil, always adhere to the recommended safe limit.

A provided oil dipstick should guide you of the right amount of oil to add. The oil level should be above the “Add” mark on the dipstick and not above the “Full” mark.

Blown head gasket

If you notice oil leak on air filter and your lawn mower is not starting, then chances are that the head gasket is blown or damaged. Other than sealing the combustion gases within the cylinders, head gasket also help in preventing engine oil from leaking into the cylinders, carburetor and other areas.

The only way of stopping this nature of oil leak and unexpected loss of engine power is by replacing the blown or worn out head gasket.

Oversaturated air filter

After cleaning your lawn mower air filter, application of little oil makes it effective in trapping dust particles. Oversaturating your air filter with oil not only make it ineffective but also a threat to other parts of the engine. The excess oil will leak into the carburetor and impair its performance.

If you accidentally sprinkle too much oil on the foam filter, then wrap a paper towel around the filter and squeeze out excess oil.

What to do about Soaked Air Filters

If you did not tilt your lawn mower, overfilled the crankcase or oversaturated air filter with oil, then there is an internal problem that is causing the oil to leak through the lawn mower air filter. You can inspect and fix oil soaked filters but before you do anything, observe safety first.

Take your lawn mower in a well-ventilated area, switch off the engine and allow it to cool. Then, disconnect spark plugs wire so that the engine does not accidentally start. If possible, wear safety glasses, respirator mask and work gloves.

Once you have identified and fixed the leading cause, the oil-soaked air filter will need to be cleaned or replaced. Additionally, you’ll also have to clean your lawn mower carburetor and spark plugs to remove oil spills.

  1. Remove the air filter casing and proceed to remove the air filter. This will also give you access to the carburetor and you can opt to clean it using a carburetor cleaner spray.
  2. Wash the foam or dual element filter with hot water and a grease cutting soap. Rinse it and use a paper towel to drain as much water as possible.
  3. Clean any dirt or debris from the rubber gasket that seals the air filter to the carburetor and inspect if there are any tears or damages for a replacement.
  4. Dab the filter with a clean motor oil, but not too much to drip off it and fix it back on the carburetor then put the housing back on.
  5. Remove the spark plug and clean it with a wire brush and a spray formulated for spark plugs. If you suspect the plug is badly damaged by the oil, you can simply replace it with new one.
  6. Once you have reassembled everything, start the lawn mower engine. Let any oil that spilled on the engine burn. You will realize blue or white smoke coming from the engine as the oil burns.

Final Thought

It is not a surprise for a lawn mower air filter to get clogged or soaked in oil. We have seen why this happens and how to fix the problem. Cleaning or replacing a lawn mower air filter is also recommended for protection of the carburetor and engine against dust, dirt and debris that would cause damages.

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