Causes Of A Lawnmower Burning Oil: Common Culprits Explained

Quick Answer: The main causes of a lawnmower burning oil include worn piston rings, a damaged valve seal, or a clogged crankcase breather. These issues can lead to excessive oil consumption and combustion, resulting in the burning smell and excessive smoke.

Are you enjoying a peaceful afternoon tending to your lawn, only to be disrupted by an unpleasant burning smell and a cloud of smoke engulfing your lawnmower? Don’t panic; you’re not alone in this predicament. Many lawnmower owners have encountered the frustrating problem of their trusty machine burning oil. But fear not, dear reader, for we are here to decode the mystery behind this unwelcome phenomenon. In this article, we will explore the causes behind a lawnmower burning oil, discussing the worn-out piston rings, damaged valve seals, and clogged crankcase breathers that may be to blame. So, let’s grab our metaphorical detective hats and dive right into the investigation, shall we?

Causes of a Lawnmower Burning Oil: Common Culprits Explained

Causes of a Lawnmower Burning Oil


Maintaining a healthy lawnmower is crucial to keeping our lawns groomed and beautiful. However, when we notice our lawnmower burning oil, it can be a cause for concern. Oil is essential for lubricating the engine and keeping it running smoothly. When oil is being burned, it indicates an underlying issue that needs to be addressed promptly. In this article, we will explore the various causes of a lawnmower burning oil and provide insights on how to troubleshoot and resolve these issues.

Potential Causes

1. Worn Piston Rings

The piston rings play a critical role in maintaining proper compression within the engine cylinders. Over time, these rings can wear down, allowing oil to seep into the combustion chamber. As a result, the oil burns during the combustion process, leading to excessive smoke and oil consumption. If you suspect worn piston rings as the cause, it is recommended to consult a professional to inspect and replace them if necessary.

2. Valve Seal Leakage

Valve seals are responsible for preventing oil from entering the combustion chamber through the valves. If these seals deteriorate or become damaged, oil can leak into the cylinder, causing it to burn. Signs of valve seal leakage include excessive smoke, oil consumption, and oil residue around the valves. Replacing the faulty seals can resolve this issue and prevent further oil burning.

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3. Overfilled Oil Reservoir

One common mistake that homeowners make is overfilling the lawnmower’s oil reservoir. When the oil level exceeds the maximum capacity, it can lead to excessive oil pressure and result in oil burning. To avoid this issue, always refer to the lawnmower’s manual for the recommended oil capacity and fill the reservoir accordingly. Regularly check the oil level and adjust it as needed.

4. Faulty Breather Tube

The breather tube, also known as the crankcase ventilation system, allows built-up pressure and gases to escape from the engine. If the breather tube becomes clogged or damaged, it can cause pressure to build up inside the engine, leading to oil leaks and ultimately oil burning. Inspect the breather tube for any blockages or signs of damage, and replace it if necessary.

5. Blown Head Gasket

A blown head gasket can allow oil to leak into the combustion chamber, resulting in oil burning. This issue is often accompanied by white smoke and a noticeable drop in engine performance. Depending on the severity of the gasket damage, it may need to be replaced by a professional. Regularly monitoring the coolant level and checking for signs of oil contamination can help identify a blown head gasket early on.

6. Engine Overheating

When a lawnmower engine operates at extremely high temperatures, it can cause the oil to break down and burn. Overheating can be caused by various factors, such as a malfunctioning cooling system, clogged air filters, or excessive grass buildup around the engine. Regularly clean the cooling system, replace air filters as recommended, and ensure proper airflow around the lawnmower to prevent overheating.

7. Low-Quality or Contaminated Oil

Using low-quality or contaminated oil can contribute to oil burning in lawnmowers. Inferior oil may not have the necessary viscosity to lubricate the engine effectively, leading to increased friction and burning. Contaminated oil, such as oil mixed with gasoline or dirt, can also disrupt proper engine function and cause oil burning. Always use high-quality oil and ensure it is free from any contaminants.

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8. Improper Storage and Maintenance

Improper storage and maintenance practices can also contribute to a lawnmower burning oil. If the lawnmower is stored in a tilted position or without proper drainage, oil can seep into the combustion chamber. Additionally, neglecting regular maintenance, including oil changes and filter replacements, can lead to oil degradation and burning. Store the lawnmower in a level position and follow the manufacturer’s maintenance guidelines to prevent oil-related issues.

A lawnmower burning oil is a problem that requires timely attention and investigation. By understanding the potential causes, such as worn piston rings, valve seal leakage, overfilled oil reservoirs, faulty breather tubes, blown head gaskets, engine overheating, low-quality or contaminated oil, and improper storage and maintenance, you can troubleshoot and resolve the issue effectively. Regular maintenance and addressing any arising issues promptly will ensure your lawnmower remains in optimal condition, allowing you to enjoy a well-maintained lawn.

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Frequently Asked Questions

What are the common causes of a lawnmower burning oil?

There could be several reasons why a lawnmower is burning oil. It’s important to identify the cause in order to address the issue effectively:

Why is my lawnmower burning oil after sitting unused for a while?

If your lawnmower burns oil after being inactive for a period of time, it could be due to the formation of carbon deposits on the piston rings. These deposits prevent the rings from sealing properly, allowing oil to leak into the combustion chamber and burn.

What could cause my lawnmower to burn oil excessively?

Excessive oil consumption in a lawnmower can be attributed to a worn-out or damaged piston rings, valve stem seals, or a faulty breather tube. When any of these components fail, oil can leak into the combustion chamber and be burned along with the fuel.

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Why is my lawnmower burning oil and producing blue smoke?

If your lawnmower is emitting blue smoke while running, it indicates that oil is being burned along with the fuel. This could be caused by worn-out valve seals, damaged piston rings, or an overfilled oil reservoir.

What can I do to prevent or fix oil burning in my lawnmower?

To prevent or fix oil burning in your lawnmower, you should regularly check and change the oil according to the manufacturer’s recommendations. Additionally, ensuring the breather tube is clean and free of clogs, replacing worn-out piston rings or valve seals, and maintaining proper oil levels can help address the issue.

Is there a possibility that the lawnmower burning oil is a sign of a more serious problem?

In some cases, excessive oil consumption or burning can be an indication of a more serious underlying issue, such as a damaged engine block or cylinder head. If you have tried the usual remedies and the problem persists, it is recommended to seek professional assistance to diagnose and resolve the problem.

Final Thoughts

The causes of a lawnmower burning oil can stem from a variety of factors. One possible cause is worn or damaged piston rings, which can lead to oil leaking into the combustion chamber. Another possible culprit is a clogged or dirty air filter, which can cause oil to be drawn into the engine. Additionally, an overfilled oil reservoir can result in excess oil being burned during operation. It is important to regularly inspect and maintain your lawnmower to prevent these issues and ensure optimal performance. Keeping an eye out for symptoms such as excessive smoke or oil consumption can help identify and address the causes of a lawnmower burning oil.