Why Is Oil Coming Out of My Lawn Mower Exhaust?

By Desmond J.

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Are you seeing oil coming out of your lawn mower exhaust? If so, you’re not alone. Many people are reporting this issue recently. And unfortunately, there’s no clear answer as to why it’s happening.

Some people believe that the oil is simply leaking from the engine. Others think that it might be caused by an issue with the carburetor or fuel line. There’s also a chance that the oil is coming from the air filter or other parts of the machine.

The good news is that this problem can usually be fixed fairly easily. If you think the oil is leaking from the engine, you can try tightening up all of the bolts and screws. If the carburetor or fuel line is at fault, those can be replaced easily enough.

10 Causes to Your Lawn Mower’s Exhaust for Oil to Come Out!

There are a few things that could be causing the oil to come out of the exhaust on your lawn mower. One possibility is that there is a leak in the engine, which is allowing the oil to escape. Another possibility is that the oil is coming from the air filter, which may not be properly sealed. If the air filter is not sealed correctly, it can allow oil to escape and drip down onto the exhaust pipe. Another possible cause of oil coming out of the exhaust is a problem with the carburetor. If there is something wrong with the carburetor, it can cause too much oil to be drawn into the engine, which will then escape through the exhaust. If you are having trouble figuring out where the oil is coming from, you may want to take your lawn mower to a mechanic for inspection.

Leaks From Tipping the Mower

When you are done cutting the grass, take a look at the back of your mower. If there is oil coming out of the exhaust pipe, it means that the oil is leaking from tipping the mower.

One common cause of this problem is when the blade hits a rock or other hard object and sends a shock wave up into the engine, causing it to leak oil. Another possibility is that there’s a crack in the engine block, which will allow the oil to escape. The best way to prevent this from happening is to be careful when you are mowing and avoid hitting any hard objects.

Overfilled Crankcase

The overfilled crankcase is one of the main causes for oil to come out of the exhaust. When a crankcase has too much oil, it will escape from seals and gaskets and travel through the engine, where it will be burned along with the fuel. This can cause significant damage to the engine, as well as decreased performance and reduced fuel economy.

Worn Valves

If the valves in your engine are not functioning properly, oil can leak out and be expelled through the exhaust. One common symptom of worn valves is an excessive amount of oil coming out of the exhaust pipe. You may also notice that your car is using more oil than usual. If you suspect that your valves are worn, have a mechanic check them out. Worn valves can cause serious damage to your engine, so it’s important to address the problem as soon as possible.

Clogged Air Filter

If you’re noticing a large amount of oil coming out of your exhaust, the likely culprit is a dirty air filter. When your air filter gets too dirty, it can’t do its job of filtering out impurities from the air. This causes dirt and other contaminants to enter the engine, where they can mix with the oil and cause excessive smoke and leaks.

Learn More: How To Clean Lawn Mower Air Filter – A Step-by-Step Guide

Damaged Piston Ring

If your lawn mower is emitting oil from its exhaust pipe, it could be due to a damaged piston ring. The piston ring seals the engine’s combustion chamber and helps to prevent the escape of gases and oil. When the piston ring is damaged, it can allow oil to escape into the engine’s exhaust system. This can cause problems with the engine’s performance and may also lead to an increase in emissions. If you suspect that your lawn mower is emitting oil from its exhaust, it is important to have the engine inspected by a professional technician.

Cracked Engine Block

One of the telltale signs that you have a cracked engine block is when oil starts to come out of the lawn mower exhaust. This problem can be caused by a number of factors, but the most common reason is that the engine block has cracked. If you suspect that your engine block may be cracked, take your lawn mower to a mechanic for inspection. In some cases, a cracked engine block can be repaired, but in other cases, it may be necessary to replace the entire engine.

Poor Operating and Maintenance Skill

There is no mistaking the black smoke and oil coming out of the exhaust pipe on a lawn mower. It’s not a pretty sight and it’s definitely not good for the environment. But what’s even worse is that it’s a sign of poor operating and maintenance skills.

Tipped Lawn Mower

When the lawn mower is tipped over, the oil that is used to lubricate the blades leaks out and mixes with the gasoline. This creates an emulsion that is then expelled from the exhaust pipe. This problem can be avoided by making sure that the lawn mower is always in an upright position.

Worn Valves

Another reason for the oil leakage might be that the gaskets or seals on the engine are damaged or worn. This will also allow oil to escape from the engine and travel through the exhaust system. If you are experiencing this issue with your lawn mower, it is important to take it in for repair as soon as possible.

Damaged Piston Ring

There is a motor at the back that powers the blade. The motor has a piston that moves up and down inside of it. A piston ring is a piece of metal that sits around the piston and helps to seal the engine. Sometimes, when the engine gets very hot, the piston ring can become damaged. If this happens, then oil can start to leak out of the engine and come out of the exhaust pipe. This can cause a lot of pollution and can be dangerous for people nearby.

How to Prevent Oil Leaking From Lawn Mower Exhaust?

Mowing the lawn is a summer tradition, but it’s important to do it safely. One hazard to be aware of is oil leaking from the lawn mower exhaust. This can happen when the engine oil level is too high and it flows over the exhaust pipe. It can also occur if the gasket between the engine and the exhaust pipe becomes damaged.

The best way to prevent oil from leaking from the lawnmower exhaust is to keep the engine oil level as low as possible. When you fill up the mower’s tank, only add enough oil to bring the level up to the “full” mark on the dipstick. Don’t overfill it, or you could end up with an oil leak.

Repair or Replace the Clogged Air Filter

A clogged air filter can prevent the engine from getting enough air, resulting in oil leakage. If the air filter is clogged, clean or replace it as necessary. Once the air filter is taken care of, check the engine oil level and make sure it’s at the correct level. If it’s not, add oil as needed. Finally, make sure the mower blades are sharp and in good condition; a dull blade can cause excess wear on the engine and lead to oil leakage.

Adjust The Carburetor

The carburetor on your lawn mower needs to be adjusted if you are experiencing oil leaking from the exhaust. This is a common issue, and can easily be fixed. The first step is to identify where the oil is coming from. If it is leaking from the exhaust pipe, then the carburetor adjustment will fix the issue. If the oil is leaking from the air filter, then you will need to replace the air filter.

To adjust the carburetor on your lawn mower, you will need to find the screws that control the idle speed and fuel mixture. Turning these screws clockwise will increase the idle speed and make the fuel mixture richer. You may also need to adjust these screws if you are experiencing problems with starting your lawn mower.

Check the Muffler

The first thing is to make sure that the muffler is in good condition. If it is not, you may need to replace it. You can also try tightening the clamps that hold the muffler in place. If neither of these solutions works, you may need to replace the gasket on the muffler.

Squeeze the Excess Oil From the Foam Air Filter

Start by removing the air filter from the lawn mower. You can do this by unscrewing the Phillips head screws that hold it in place. Once the filter is off, use the screwdriver to pry open the four tabs around the edge of the filter. Then, use your hands to squeeze all of the excess oil out of the filter.

Once you’ve squeezed out all of the oil, reattach the air filter to the lawn mower and replace all of the screws.

Replace the Worn Valves

Replacing the worn valves is an easy fix and can prevent oil from leaking in the future. First, remove the spark plug wire and cap to prevent accidental starting. Next, loosen the bolts that hold the muffler in place. Be careful not to damage the wires or hoses while doing this. Remove the muffler and then the valve cover. The valves can now be replaced by unscrewing them and putting new ones in their place. Make sure that they are properly tightened before putting everything back together.

Fixing Internal Problems

One solution is to tighten the bolts on the exhaust pipe. This may fix the problem temporarily, but it’s likely that the bolts will loosen up over time and the oil will start leaking again. A better solution is to replace the gasket between the exhaust pipe and the engine. This is a cheap and easy fix that will stop the oil from leaking for good.

​How To Avoid Placing Too Much Oil

When it comes to oil, it’s important not to use too much. This is because using too much oil can lead to negative consequences, such as decreased engine performance and damage to the environment.

If you do happen to put too much oil in your lawn mower, don’t worry! You can fix the issue by following these simple steps:

1) Shut off your machine and let it cool down completely.

2) Carefully remove the oil cap and pour out or siphon out the excess oil.

3) Wipe down the area beneath your lawn mower to remove excess oil.

4) Reattach your oil cap, turn on your machine and enjoy!


In conclusion, it would seem that my lawn mower is burning oil, and this is causing the black exhaust that I’ve been seeing. While it’s not a huge issue, it’s something that I’ll need to address in order to keep my mower running properly. I’ll need to take it in for a tune-up, and maybe even consider upgrading to a newer model.

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Written By
Desmond J.
I'm a lawn mowing expert and gardening enthusiast. I started my own lawn care business in college and have been doing it ever since. I love taking care of lawns and gardens, and I'm always looking for new ways to improve my skills. I'm also a big fan of composting and using natural fertilizers.

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