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 have been reporting on this issue. And there’s no logical answer to why it’s happening.

Some people believe that the oil is leaking from the engine. Others think an issue might cause it with the carburetor or fuel line. There’s also a chance that the oil comes from the air filter or other parts of the machine. So what’s the major cause for seeing oil out for lawn mower exhaust? And how to fix this issue?

If the exhaust coming out of the lawn mower’s carburetor contains oil, it is typically from the lawn mower being tilted incorrectly, putting in too much oil, a carburetor imbalance, a clogged air filter, or damage to the engine.

Let’s dig deeper and know more about it!

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

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

1. Leaks From Tipping the Mower

When you are done cutting the grass, look at the back of your mower. If oil comes out of the exhaust pipe, 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 into the engine, causing it to leak oil. Another possibility is a crack in the engine block, which will allow the oil to escape. The best way to prevent this is to be careful when mowing and avoid hitting any hard objects.

2. Overfilled Crankcase

The overfilled crankcase is one of the major causes of oil coming 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 burns along with the fuel. It can cause significant damage to the engine, decreased performance, and reduced fuel economy.

3. Worn Valves

If the valves in your engine are not functioning, oil can leak out and be expelled through the exhaust. One common symptom of worn valves is excessive oil from the exhaust pipe. You may also notice that your car is using more oil than usual. If you suspect 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.

4. Dirty Air Filter

If you notice 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. A dirty air filter causes dirt and other contaminants to enter the engine, where they can mix with the oil and cause excessive smoke and leaks.

5. Damaged Piston Ring

If your lawn mower emits oil from its exhaust pipe, it could be because of 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. It 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.

6. Cracked Engine Block

One of the telltale signs that you have a cracked engine block is when oil comes out of the lawn mower exhaust. Several factors can cause this problem, but the most common reason is that the engine block has cracked. If you suspect your engine block may be cracked, take your lawn mower to a mechanic for inspection. Sometimes, a cracked engine block is repairable, but in other cases, it may be necessary to replace the entire engine.

7. Poor Operating and Maintenance Skill

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

8. Tipped Lawn Mower

When the lawn mower is tipped over, the oil lubricates the blades, leaks out, and mixes with the gasoline. It creates an emulsion that is then expelled from the exhaust pipe. You can easily overcome this problem by making sure that the lawn mower is always in an upright position.

9. 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 seal the engine. When the engine gets boiling, the piston ring can become damaged. If this happens, oil can leak out of the engine and come out of the exhaust pipe. It can cause a lot of pollution and be dangerous for nearby people.

How to Prevent Oil from 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. When the engine oil level is too high, 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 filling 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.

1. 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 ensure it’s at the correct level. If it’s not, add oil as needed. Finally, ensure the mower blades are sharp and in good condition; a dull blade can cause excess wear on the engine and lead to oil leakage.

2. Adjust the Carburetor

If you are experiencing oil leaking from the exhaust, the carburetor must be adjusted. It’s a common issue and easy to fix. The first step is to identify where the oil is coming from. If it is leaking from the exhaust pipe, then the carburetor change will fix the issue. If the oil leaks from the air filter, you will need to replace the air filter.

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

3. Check the Muffler

The first thing is to ensure 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.

4. 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 filter’s edge. Then, use your hands to squeeze the excess oil out of the filter.

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

5. 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. You can easily replace the valves by unscrewing them and putting new ones in their place. Make sure that it properly tightened before putting everything back together.

6. Fixing Internal Problems

One solution is to tighten the bolts on the exhaust pipe. It may fix the problem temporarily, but the bolts will probably 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 cheap and easy fix will stop the oil from leaking for good.

Why Does This Problem Need to Be Solved Urgently?

If you’ve ever operated a gas-powered lawn mower, you know the telltale sign of a problem: black smoke billowing from the exhaust pipe. Operators of these machines may not be aware of the dangers of oil leaking from the engine and entering the exhaust pipe.

When oil is burning in the engine, it creates a black sooty substance that can coat nearby objects, including people. Not only is this an eyesore, but it’s also dangerous to breathe in. Inhaling oil fumes can cause respiratory problems and even death.

This problem needs to be resolved urgently. If you notice black smoke coming from your lawn mower’s exhaust pipe, take it to a mechanic for repair immediately.

​How to Avoid Placing Too Much Oil

For oil, it’s important not to use too much. Because using too much oil can lead to negative consequences, such as decreased engine performance and environmental damage.

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

  • Shut off your machine and let it cool down completely.
  • Carefully remove the oil cap and pour or siphon the excess oil.
  • Wipe the area beneath your lawn mower to remove excess oil.
  • Reattach your oil cap, turn on your machine and enjoy!

Warping Up

In conclusion, my lawn mower is burning oil, 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 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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