Lawn Mower Air Filter Soaked in Oil? Causes + Fixes

Lawn mower air filters are designed to trap dirt and debris from the air before it enters the engine through the carburetor. Clogged air filter leads to problems like engine sputtering, increased fuel consumption, and difficulty starting up. Here is an explanation of why your lawn mower air filter is soaked in oil and how to fix the problem.

Lawn mower flipping over, excess oil in the crankcase, and blown head gasket are the main reasons why lawn mower air filter is soaked in oil. The best solution to this problem is to remove the oil-soaked air filter and replace it with a new one.

Why is my Lawn Mower Air Filter Soaked in Oil?

The oil-soaked air filter is a serious lawn mower problem that should be fixed urgently. Based on observation, the following are reasons why a lawn mower air filter is soaked in oil.

1. Tilting your lawn mower

Tilting a lawn mower at an angle of more than 45 degrees with its carburetor facing downward will make oil escape from the crankcase into the other parts of the engine, including air filters.

In many cases, we tilt our lawnmowers when we want to clean the bottom of the mowing deck, sharpen lawn mower blades, or cut grass on slopes and slanted grounds. Tilting your lawn mower with the carburetor facing on the high side can help prevent oil spills on the air filter.

2. Overfilled oil crankcase

Most engine parts will get soaked in oil that escapes from an overfilled crankcase. The excess oil will move into the carburetor and out through the air filter. Always use a dipstick to check the recommended level when changing lawn mower engine oil.

The oil level should be above the “Add” mark on the dipstick and below the “Full” mark.

3. Blown head gasket

If you notice an oil leak on the air filter and your lawn mower is not starting, the head gasket is likely blown or damaged. Besides sealing the combustion gases within the cylinders, the head gasket also helps prevent engine oil from leaking into the cylinders, carburetor, and other areas.

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

4. Oversaturated air filter

After cleaning your lawn mower air filter, applying little oil makes it effective in trapping dust particles. However, oversaturating your air filter with oil makes it ineffective. The excess oil will also 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

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 the spark plug wire, so the engine does not accidentally start. Wear safety glasses, respirator masks, and work gloves if possible.

Go through the owner’s manual and identify the problem’s primary cause. Once you have fixed the leading cause, remove, clean, or replace the oil-soaked air filter. You’ll also have to clean your lawn mower carburetor and spark plugs to remove oil deposits.

  1. Remove the air filter casing and proceed to remove the air filter. This will also give you access to the carburetor.
  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 clean motor oil, but not too much to drip off it, fix it 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 oil badly damages the plug, you can replace it with a new one.
  6. Once you have reassembled everything, start the lawn mower engine. Don’t worry if your lawn mower is smoking; the oil spilled on the engine is simply burning.

Final Thought

It is common for a lawn mower’s air filter to get clogged or soaked in oil. We have seen why this happens and how to fix the problem. Regular cleaning or replacing a lawn mower air filter is also recommended to protect the carburetor and engine against dust, dirt, and debris.

Leave a Comment