Why is Oil Coming Out of My Lawn Mower Exhaust: How To Fix It?

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Once the engine oil has been poured in, it should remain hidden until it is time to be refilled or replaced. In particular, your gasoline and oil are kept in a compartment that is physically distinct from the exhaust system. So any signs of lawn mower leaking oil from exhaust should raise red flags.

However, the displacement of specific engine oil is easier than you may imagine. One brilliant place to fix your lawnmower is by finding out how the oil got into the exhaust.

Oil leaks out of the exhaust when the lawnmower is tilted improperly when too much oil is added. The carburetor is out of balance, the air filter is blocked, or the engine is damaged. These problems often have simple solutions, although it might be challenging to identify their origin.

Why Your Lawn Mower Leaking Oil From Exhaust?

Why Your Lawn Mower Leaking Oil From Exhaust
Image Source: lawnmoweradvice

Want to know the reasons behind your lawn mower leaking oil? Check all factors here.

1. Lawnmower Oil Leakage Because of Improper Tilting

Many problems might arise from using a lawn mower in the wrong direction. Oil seeping from the engine’s crankcase into the cylinders is one of them. The oil will then be forced out of the exhaust valve. It is most likely the source of the oil on your air filter.

2. Overfilling The Oil in Your Lawnmower

If you overfill the lawn mower’s oil reservoir, it will eventually start leaking. Too much oil in the crankcase may cause the same issues as an improperly tilted mower, including smoke from the exhaust pipe.

3. Misaligned Carburetor

Mismatched air and fuel entering the engine because of an unbalanced carburetor may cause oil and gas to escape via the tailpipe. Some of the fuel will undoubtedly be wasted, but whatever isn’t burnt will be expelled anyhow.

Since some of the fuel will be lost in the process, this results in higher overall fuel usage. If this is your situation, and you see a gas-and-oil mixture pouring from your exhaust, you should consider it.

4. The Air Filter is Blocked

Exhaust fumes smelling like oil and gas are a few signs of a filthy air filter, among many others (though usually just in extreme cases). If your air filter is dirty, your engine may not get enough oxygen to burn the fuel it takes in properly. If the carburetor is out of whack, gasoline will seep out, and you’ll lose power.

5. Torn Axle

Oil seeping from the exhaust might be a sign of engine problems, which is something no one likes to find out about their mower. Oil leaks may be caused by several issues, including worn valves, broken piston rings, blown head gaskets, and fractures in the engine block.

Things may look a little more severe if you have tested everything else and have an older mower.

Four-Stroke Lawnmower With Oil Leaking Out of The Exhaust

Four-Stroke Lawnmower With Oil Leaking Out of The Exhaust
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Mowers that use a four-stroke engine keep the gas and oil in different compartments of the crankcase. You may compare it to an automobile because the oil and fuel are kept in separate containers.

Since liquids other than oil may leak into the exhaust, this is a concern. Sometimes unburned gas leaks, and it looks like oil because it has accumulated so much carbon and become so dark. When troubleshooting a four-stroke mower, it is essential to verify that the leaking liquid is not engine oil.

For instance, if you see gas escaping from the vehicle, you should first inspect the air filter and the carburetor.

Two-Stroke Lawnmower Leaking Oil Through the Tailpipe

Two-Stroke Lawnmower Leaking Oil Through the Tailpipe

Mowers with a two-stroke engine need to add engine oil to their gas for lubrication. The oil additive in two-stroke engines aids in lubrication during combustion. You won’t be able to see how much oil is left in your tank after refueling since the oil and gas are kept in the same tank.

It may make it more challenging to identify the source of any exhaust leaks if any fluids are present. The same happens if you tip a two-stroke mower in the wrong direction, even though it uses a gas and oil mixture.

The Lawnmower’s Exhaust Has Oil Splatters

For the same reasons why oil may leak from the exhaust of a push mower, it can also happen to a riding mower. Riding mowers has more complex engines. When it comes to riding lawnmowers, over-oiling is more likely to be the cause of failure.

But if it isn’t, and oil is flowing out of the exhaust of your riding mower or lawn tractor, you may face the same internal engine difficulties as you would with a push mower. If you can’t handle the engine on a push mower, you’re probably not ready to take the one on a riding mower and will need to make a trip to the technician.

How to Fix Oil Coming Out of My Lawn Mower Exhaust?

With so many complications, you certainly want to fix your lawn mower exhaust to prevent further damage. Check these easy steps.

1. Keeping The Lawnmower Level at a Tilt of Over 15 Degrees Might Cause Damage

Keeping The Lawnmower Level at a Tilt of Over 15 Degrees Might Cause Damage
Image Source: lawnmowerguru

Oil tends to flow toward the carburetor and subsequently out the exhaust when the lawnmower is tilted, which occurs most often while going uphill. Over a fifteen-degree incline may cause oil to escape from the lawnmower’s crankcase and make its way toward the carburetor. The oil may leak out of the exhaust if you do this.

2. Clear The Congested Air Filter

Clear The Congested Air Filter
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Because of the incomplete combustion of the fuel, the air filter must be cleaned. A foamy framework acts as the air filter, trapping and enclosing contaminants, including dust, debris, and insects. It prevents air from entering the piston, resulting in lost potential energy.

A sufficient quantity of air cannot move through if it is damaged or has become porous. Because of this, fuel is not being burned correctly. Fixing the problem requires you to clean the filter. In the absence of such action, the leftover gasoline will seep oil.

3. Carburetor Fine-Tuning

Carburetor Fine-Tuning

The lawnmower wouldn’t work without the carburetor. There will be problems with the carburetor if it is not functioning correctly. The gasoline will not burn appropriately if the carburetor is not regularly adjusted. The exhaust will be filled with this unburned gasoline. Adjusting the carburetor should fix the problem.

4. Muffler Inspection

Muffler Inspection
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In most cases, exhaust fluid is unburned fuel. An untuned carburetor will result in wasted energy. Alternatively, the energy will not be used if the air filter is blocked.

This exhaust gas contains unburned fuel. When gas-like liquid leaks from the exhaust system, it is called flooding. The muffler must be fixed or replaced to prevent more water damage.

5. Change Out Any Worn Valves

Change Out Any Worn Valves
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Valves are installed in the lawnmower cylinders to prevent leaking. Worn valves will prevent the cylinder from being filled. Because of this, the oil will start leaking from the cylinder and eventually make its way out the tailpipe. So, change out the old, worn valves.

Also Read: Do You Need To Sharpen New Mower Blades | A Complete Guide

Recommendations For Oil Coming Out of My Lawn Mower Exhaust

  • The mower will run better when you clean and tune the carburetor, and the gasoline leak should stop.
  • Start by spraying some aerosol carb cleaning into the carburetor to clean it.
  • There’s no harm in exploring your engine if you know your way around a tiny engine and have the necessary equipment.


How to stop oil from seeping into the motor?

If you want your lawnmower to last a long time and do a good job, you must take good care of it. When lawn mowers are kept in good condition, they may last for years without losing efficiency.

What should I do if I see oil in the lawnmower’s exhaust?

Faulty filters, poor quality fluids, or harsh operating conditions may contribute to oil being expelled from the exhaust. If you feel overwhelmed by the difficulty of the situation, an expert is available to assist you.

How to determine whether my lawnmower needs oil?

One may examine the oil level using a dipstick. To begin, take it apart and wipe it down. Second, remember to reinstall the mower’s dipstick. See how high the oil has risen now? If the level reaches the top, then it is complete. But if there’s more than that, it might lead to complications.

If the air filter is leaking oil, what may be the cause?

Suppose the oil level in the filter is too high. In that case, it may leak around the filter box or be sucked into the carburetor, where it will clog the internal jets and needle valves. You should remove oil from a foam air filter or prefilter by squeezing it.


The lawnmower must be serviced regularly to function properly. However, if proper maintenance is not performed, you may meet the previously mentioned issues. It isn’t enjoyable and, in some cases, expensive.

All the points discussed above address the oil issue in the exhaust. If you are experiencing a similar problem, it is essential to investigate the root causes and potential resolutions.

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