Lawn mower blowing oil. Lawn Mower Air Filter Soaked in Oil? Causes Fixes

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.

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.

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.

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.

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.

• Remove the air filter casing and proceed to remove the air filter. This will also give you access to the carburetor.
• 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.
• 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.
• 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.
• 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.
• 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.

Lawnmower Is Burning Oil: 6 Reasons And How To Fix

A lawnmower in your garden is quintessential. It helps trim grass to an even and appropriate height and keeps weeds in check.

Typically, a lawnmower can use up to 1 ounce of oil per cylinder in an hour. That’s already massive.

However, it could burn more under problematic circumstances. When this happens, your lawnmower is burning oil.

The situation could arise from a problem with the engine or the oil. If you are experiencing such a technical issue on your lawnmower, we got some answers.

Causes of A Riding Mower Burning Oil

Cases of lawnmowers burning oil are not uncommon. These reasons range from improper storage to an overfilled crankcase.

An Overfilled Crankcase

When your lawn mower’s crankcase gets overfilled, it starts to burn oil. How does this happen?

Your lawn mower’s engine contains a piece of electromagnetic equipment called a solenoid. It is responsible for monitoring the gas flow into the engine.

The float in the carburetor connects to the solenoid. If the carburetor malfunctions or gets stuck, it prevents fuel shut off.

The result is an overflow of gas into the engine, which thins the oil.

Consequently, oil burning occurs much faster, leading to the mower producing a Cloud of white smoke.

You can fix the problem by checking the carburetor and repairing it. As a precaution, always use the manufacturer’s manual to check what oil grade is best for the machine and use only it.

Piston Rings Are Worn Out

The piston rings of your lawnmower wearing out is a potential cause for your lawnmower burning oil.

As a result of the wear and tear of the pistons, oil flows through the narrow gap between the cylinder wall and the piston, burning in the ignition chamber.

Burning of oil also occurs when the valve seats wear out. Replace any worn-out parts in your lawnmower to overcome this problem.

Using The Wrong Oil Grade

Different lawn mowers use different oil types. Using the wrong oil grade on your lawnmower could cause it to burn oil, decreasing the fuel efficiency.

Another important parameter associated with oil is viscosity. Oil with the wrong viscosity causes the lawnmower to slow down, increasing your operational cost.

Low-grade oil could also damage the lawnmower engine.

You also want to check the owner’s manual to know whether your lawnmower is meant for a lighter or heavier oil.

Using lighter oil on a heavy oil engine makes the oil burn more quickly.

Low Oil Levels In The Crankcase

A decrease of oil in the crankcase below appropriate levels is also a cause for your lawnmower burning it.

Insufficient oil causes temperatures to increase inside the crankcase due to more friction.

Oil gets burned up faster due to higher temperatures and a lack of lubrication inside the engine. A valve or a seal in the engine could also blow up.

Take care of low oil levels in the crankcase by routinely filling it up to the correct levels. This helps prevent wear and tear and repair costs in the future.

Oil Leaks

Your lawn mower could also burn oil because of oil leaks in the engine or the lubricating system.

Usually, such leaks are rarely visible, and it might take some extra checks to spot them.

Common areas the oil leaks occur include the oil gaskets, the breather cavity, and the O-ring. A tell-tale sign of an oil leak is your lawnmower emitting dark or white smoke.

Another sign of an oil leak in your mower is sluggishness or sputtering during operation.

If this happens, do check the piston rings or seals. Do a thorough inspection of your lawnmower, especially at the oil tank, the engine base, and the oil fill tube, for any leaks.

Here are some measures you can take to prevent oil leaks from happening:

• Avoid storing your lawnmower for long periods with gas and oil inside. Old oil causes the seal and gaskets to wear, making you incur the repair cost the next time you want to use it.
• Regularly check and replace any worn-out parts.
• Replace old oil with new oil after every 25 hours of use.

Storing Your Lawnmower On One Side

We hope your garage is spacious enough to store your lawnmower. However, avoid keeping it on one side if it isn’t the case.

Gardeners are also guilty of turning it on one side while replacing old oil or doing maintenance. Doing this is a potential cause for your lawnmower burning oil.

Here is what you should do to avoid this eventuality.

• Keep your spark plugs facing upwards when doing maintenance. It helps to avoid leaks from the crankcase.
• Drain oil or gas from your lawnmower before keeping it away.

How To Know When Your Lawn Mower Is Burning Oil?

Having said it all, a common sign of your lawnmower burning oil is the production of white smoke.

Often, you will also spot the production of black smoke. A high fuel to air ratio results in incomplete combustion that makes the unburnt fuel come out as black smoke.

A smoking lawn mower is never a good sign. Whether the smoke is blue, white, or black, here’s how to identity and address the issue without the help of a professional.

By Glenda Taylor and Bob Vila | Updated Sep 24, 2020 1:40 PM

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Q: Recently, my mower started billowing smoke when I powered it up, so I shut it off immediately. Why is my lawn mower smoking? And is it a fire hazard? I want to know how to proceed so I don’t harm the machine.

A: Your lawn mower can emit smoke for numerous reasons—many of which don’t require the services of an expert. A homeowner can usually identify the reason for a smoking lawn mower by gauging the color of the Cloud coming around the engine, then fix it accordingly before lasting damage occurs. Keep in mind that all mowers with internal combustion engines contain the same basic parts, but the configuration of those parts varies widely, depending on manufacturer and model. Consult your owner’s manual if you’re unsure how to access a specific part of your lawn mower’s engine.

White or blue smoke may indicate an oil spill on the engine.

If you’ve recently changed the oil in your mower and the engine is emitting white or blue smoke, it’s possible that some of the oil spilled onto the engine. Similarly, you could’ve spilled oil on the engine by mowing on a slope greater than 15 degrees or tipping the mower on its side. The smoke may look disconcerting, but it’s completely harmless. Solve the problem by restarting the mower and allowing the spilled oil to burn off. If you tip the mower often for cleaning or maintenance, check your owner’s manual to determine the best way to reduce the risk of oil leaks.

An overfull oil reservoir may also cause white or blue smoke.

Ensure you didn’t overfill the mower by checking the oil level with the dipstick located on the reservoir. To do this, remove the dipstick cap, wipe off the stick with a rag, and reinsert it into the reservoir. Then remove the dipstick once again and determine the oil level in comparison to the recommended “fill” line on the stick. If the level is too high, drain the oil (consult your owner’s manual for instructions), then refill the reservoir with it. Start checking the oil level with the dipstick after you’ve added about ¾ of the amount recommended in the manual. Continue to add small amounts of oil until the level matches the recommended “fill” line. Also note that using the wrong grade of engine oil may cause blue or white smoke. Consult the owner’s manual for the exact type of oil recommended for your mower.

Black smoke may indicate that the mower is “running rich,” or burning too much gasoline.

Your lawn mower’s carburetor regulates the ratio of gasoline to air mixture. If the carburetor isn’t getting enough air, the mixture has a higher percentage of gasoline, which can create black exhaust smoke. It’s possible that a dirty or clogged air filter is preventing sufficient airflow into the carburetor. Try replacing the air filter. (Note: air filters vary by mower model; view example air filter on Amazon.) Next, run your lawn mower for a few minutes. If the black smoke still appears, the carburetor might need to be adjusted in order to increase airflow. Either take the mower to a professional or adjust the carburetor yourself with instructions in your owner’s manual.

Take your mower to a repair shop if necessary.

If the previous steps don’t correct blue or white smoke, your mower could have a more serious problem, such as an air leak in the crankshaft (the cast iron or cast aluminum case that protects the moving parts of a mower’s engine). Continuing blue or white smoke could also indicate that some of the engine’s components or seals are worn out and need replacement. Similarly, if black smoking still persists after you’ve replaced the air filter and adjusted the carburetor, you could be facing a more serious mechanical issue. All of these problems require the help of a professional. If your mower is still under warranty, check with the manufacturer for the location of the nearest servicing dealer; problems stemming from a factory defect or poor workmanship may garner free repairs. If your mower is not covered under warranty, a reputable small-engine repair shop should also be sufficient to get the job done.

Why Does Oil Come Out Of My Lawn Mower Exhaust?

When you consider the complexity of a lawnmower engine, it is incredible that they can run consistently, with constant abuse for such long periods. The number of processes that work seamlessly at speeds of up to 96 times per second makes you realize how remarkable the engineering that goes into their manufacture is.

Three situations generally cause oil to come out of a lawnmower exhaust.

• The oil has been replaced or topped up, and the level is too high
• The operator tilted the lawnmower with the carburettor and air filter facing down
• The piston ring is worn or broken.

If oil comes out of the lawnmower exhaust, excessive motor oil has entered the top of the piston chamber and is being expelled through the exhaust valve.

There are reasons this could occur, and in most cases, it’s an easy situation to rectify.

Reasons Why Oil May Come Out Of A Lawnmowers Exhaust

There are several reasons why oil may come out of a lawnmower’s engine exhaust. The most common issues are simple to fix.

• The Oil Level Is Too High.
• The Operator Tilted The Lawn Mower The Wrong Way.
• The Piston Ring Is Worn.

The Oil Level Is Too High

If the lawnmower’s crankshaft has been filled past the dip stick’s maximum mark, you should rectify this immediately.

Overfilling a lawnmower oil tank can result in the oil being whipped into foam by the crankshaft, expanding it.

Four-stroke lawnmowers generally have a vent that draws air from the crankcase to the air filter box. If the oil is overfilled, the now expanded and aerated oil will travel to the carburetor via the crankcase vent.

It will result in a considerable amount of oil being drawn into the running engine through the inlet valve, and if the engine stays running, it will result in more smoke than you’d have thought possible

Excess motor oil will be forced out of the chamber when the exhaust valve opens because the oil enters the piston chamber from the top (through the inlet valve). It will cause oil to come out of the lawnmower exhaust.

In an extreme situation, too much oil can build up enough pressure in the crankcase to push out or deform valve seals and even the head gasket.

The Operator Tilted The Lawnmower The Wrong Way

The lawnmower being, so the carburetor faces down, the oil will flow through the crankcase breather into the carburetor.

Just as excess oil may enter the piston chamber through the inlet valve, the oil flowing to the carburetor will also do the same and be expelled through the exhaust valve.

It will cause oil to come out of the lawnmower exhaust.

The Piston Ring Is Worn

A worn piston ring may allow the oil splashed from the crankcase to the bottom of the piston chamber to move past the worn piston ring and into the top of the piston chamber.

Once the oil reaches this area, it will be expelled through the exhaust valve and come out of the lawnmower exhaust.

A piston ring will wear out for the following reasons.

The Engine Is Old And Tired

The engine is old and eventually requires a rebuild.

The Oil Is Not Changed Often Enough

The ring will wear if the oil is not regularly changed with the correct viscosity oil.

The Air Filter Is Dirty

If the air filter is dirty, dirty may enter the piston chamber and damage the ring.

The air intake is close to the dust, which is thrown up and often does not seal, resulting in a damaged ring.

The Lawn Mover Cooling Fins Are Blocked

A lawnmower engine will overheat if gunk builds up around the engine’s cooling fins, which may result in a damaged or broken ring.

It makes the cylinder and piston run at higher temperatures. The extra heat removes the temper of the rings, and they become soft.

The Valve Seals Are Damaged Or Worn

If the exhaust valve has become unseated, the engine may not entirely remove the exhaust gasses, and the motor could overheat, resulting in a damaged or broken piston ring.

The symptoms of a broken or damaged piston ring are.

• There is a loss of engine power.
• Large volumes of white smoke are blown out of the lawnmower exhaust.
• If a piston ring becomes worn or broken, the piston will start to knock against the cylinder wall.
• The lawnmower oil consumption increases.
• You may see oil come out of the lawnmower exhaust.
• A pressure below 70Psi will indicate a damaged piston ring if you have a compression gauge.

How Does A Lawnmower Use Oil?

The oil keeps the internal moving engine parts lubricated.

A lawnmower internal combustion engine works through 4 cycles.

• As the piston rises, the intake valve opens, and the carburetor sends the correct fuel/air mixture into the piston chamber via the intake valve.
• The valves close and seal the chamber, and the fuel/air mixture is compressed by the piston rising in the chamber.
• As the piston reaches the top, the coil sends a 20,000-to-30,000-volt impulse, making the spark plug ignite the fuel /air mixture, which causes an explosion, and the resulting gas expands and forces the piston down.
• The exhaust valve opens and forces the burnt exhaust gasses out.

The moving piston turns the lawnmower’s crankshaft, which rotates the mower blades.

This sequence happens at very high speeds and for long durations. The piston of a typical walk-behind lawnmower moves up and down more than 48 times every second.

The tolerances of the valves, piston rings, and piston chamber are measured in 0.001-inch increments.

Although removing the exhaust gasses via the exhaust valve reduces the temperature, without a continuous oil supply, the heat caused by the friction of the piston (with rings installed) moving up and down the cylinder 96 (48 up and 48 down) times per second, would cause the piston and rings to expand and seize against the piston wall.

How Does A Lawnmower Engine Move Oil Around?

To counter this part of the cycle involves the crankshaft collecting oil and sending it onto the walls of the piston chamber.

Modern lawnmowers use one of the following methods to distribute oil into the piston chamber.

A splash system involves a spinning gear with paddles installed, immersed in oil that slings lubricant throughout the crankcase.

A pressure oil distribution system uses a more controlled oil pump to collect the oil and distribute it to the crankcase mechanically.

A full pressure system is only found in high-end, ride-on machines. The system works in the same way an automobile engine does, in that a controlled pump constantly distributes oil to the crankcase.

How Do You Stop Oil Coming Out Of A Lawnmower Exhaust? [Solution]

The following is the remedy for each of the three reasons oil may be coming out of the lawnmower’s exhaust.

The Oil Level Is Too High

If oil is coming out of the lawnmower exhaust because it is too high, it is essential to reduce the oil level immediately.

Because the change in temperature and pressures may have changed the oil’s viscosity, the best method is to fully drain the oil tank and refill it with the correct quantity of fresh oil.

The Operator The Lawnmower The Wrong Way

In most instances, leaving the lawnmower standing for a few hours will be sufficient time to drain the oil back into the crankcase where it originally came from.

Apart from a short period where the lawnmower produces clouds of smoke, the lawnmower is not damaged, and you can carry on.

The Piston Ring Is Worn

If the piston rings are worn, they will need to be changed sooner or later.

It is not hard to replace the piston ring yourself; however, if you are not confident of your ability, this is best left to a trained lawnmower technician.

Conclusion

Most gardeners have noticed oil coming out of their lawnmower’s exhausts at some time. Often it is caused by tilting the lawnmower, so the carburetor and air filter face down, or the oil tank has been overfilled.

If the lawnmower has been operated in very dusty environments and it is an old machine that has worked for many hours, it is possible that the piston ring is worn and needs to be replaced.

Author

Jason is an expert writer and is passionate about Smart Homes and Home Improvements writing as well as lifestyle and Lawn Care. He spent the past twelve years living in Hawaii, where he worked closely alongside event planners and resort owners to perfect his knowledge of luxury products and aesthetics. He discovered his passion for DIY projects and home improvement there. Currently, he lives in Washington D.C with his family and 2 pets. View all posts