Why is My Lawn Mower Smoking? Troubleshoot Guide.

Why is My Lawn Mower Smoking Troubleshoot Guide
Why is My Lawn Mower Smoking Troubleshoot Guide

If your lawn mower is smoking, it could be due to an oil or fuel problem. Lawn mower smoking is a common issue that lawn owners face.

Smoke from a lawnmower can be an indication of serious mechanical problems, and it’s important to understand the reason. Smoke may also imply that the mower’s air filters and fuel filters need to be cleaned, or it might indicate that the engine oil has leaked and fallen onto the muffler.

Also, overfilling the oil tank in your mower can cause it to smoke. Knowing what causes your lawn mower to smoke makes it possible to maintain it effectively and avoid costly repairs. If you take care of your lawn mower properly, it will efficiently mow your lawn for years to come.

Understanding The Types Of Lawn Mower Smoke

Lawnmowers are essential tools for anyone who loves a well-maintained lawn. They come in different types, sizes, and shapes to suit various needs. However, even the best lawn mower can encounter issues, including smoking.

Differentiating Between White, Blue, And Black Smoke With Examples And Descriptions

White Smoke

White smoke can occur due to various reasons, some being:

  • Moisture in the gas
  • Mixing too much oil with fuel
  • Air leaks in the engine

If you see white smoke emanating from your lawn mower, it is usually a sign of water vapor, which may have accumulated in the engine. This type of smoke is harmless and usually disappears once the moisture evaporates. If white smoke continues to come out of your lawn mower, it may be signifying a problem with your engine.

Blue Smoke

Bluish smoke is common in 2-cycle engines and could imply a damaged engine. It could occur due to the following reasons:

  • Dirty air filter
  • Overfilling crankcase oil
  • Worn piston rings
  • Damaged engine valve

If the lawn mower is older and has been used for an extended period, the blue smoke could indicate a more significant issue that requires immediate repairs.

Black Smoke

When the lawn mower produces dark smoke, it usually indicates a fuel-rich situation. This type of smoke may be a sign of a clogged air filter, outdated or contaminated fuel, or carburetor issues. The most common causes of black smoke are:

  • Clogged air filter
  • Excessive fuel pressure
  • Faulty carburetor
  • Dirty or broken fuel injector

If the lawn mower continues to produce black smoke and you are sure that the cause is not due to any of the issues listed above, it is best to seek professional help.

Additionally, check out: How to Clean Lawn Mower Carburetor

By understanding different types of smoke and their possible causes, you can easily troubleshoot your lawn mower’s smoking issues before they escalate. Remember that regular maintenance can help your lawn mower perform efficiently and avoid unpredictable problems.

Common Reasons For Smoking Lawn Mowers

Has your lawn mower been smoking more than usual during use? This could be a sign that your mower is encountering some problems. There are many reasons why a lawn mower might start to smoke, and it’s essential to identify the root cause of the issue.

In this guide, we’ll dive into some common reasons why your lawn mower might be smoking, as well as some simple steps to help you fix the problem.

Dirty Or Clogged Air Filters

One of the common reasons for smoking lawn mowers is due to dirty or clogged air filters. Over time, the air filter gets jammed with dirt, grass, and other debris. If your lawn mower is running with a clogged air filter, the engine will not get enough air, and the oil and gas will mix, leading to smoke.

  • Check the air filter to see if it’s dirty.
  • If the filter is dirty, remove it and clean it entirely.
  • If the filter is damaged, replace it with a new one.

Corroded Or Damaged Spark Plugs

Another reason why your lawn mower might be smoking is due to corroded or damaged spark plugs. The spark plug is responsible for igniting the fuel in the engine. If the spark plug is damaged or corroded, it won’t be able to ignite the fuel completely, leading to smoke.

  • Check the spark plug to see if it’s damaged or corroded.
  • If it’s damaged or corroded, replace it with a new one.

Leaking Fuel Lines

Leaking fuel lines are another common reason why a lawn mower might smoke. If the fuel line is broken or damaged, it can cause fuel to leak out of the mower, leading to an increased risk of fire or explosion.

  • Check the fuel line for any leaks or damage.
  • If you find any leaks or damage, replace the fuel line immediately.

Overfilled Or Old Engine Oil

Overfilled or old engine oil can also cause a lawn mower to smoke. If the oil level is too high, it can cause the engine to burn off extra oil, leading to smoke. Also, if the oil is old, it can break down and lose its lubricating properties, leading to increased engine wear and tear.

  • Check the oil level in the mower. If it’s too high, remove the excess oil.
  • If the oil is old, drain it and replace it with fresh oil.

Damaged Piston Rings

A damaged piston ring can cause your lawn mower to smoke. The piston rings create a seal between the piston and the cylinder wall, preventing oil from entering the combustion chamber. If the piston ring is damaged or worn out, it can allow oil to enter the combustion chamber, leading to smoke.

  • Check the piston rings for damage.
  • If the piston rings are damaged, substitute them immediately.

Loose Or Broken Connections

A loose or broken connection can cause a lawn mower to emit smoke. If there is an electrical issue, for example, it can cause the engine to run poorly, leading to smoke.

  • Check the electrical connections to make sure they are safe.
  • If you find any loose or broken connections, repair or replace them immediately.

Furthermore, consider reading: What is a Brushless Lawn Mower?

Smoking lawn mowers can be caused by a variety of factors, but identifying the root cause quickly is essential to make the necessary repairs and avoid further damage. By following the steps outlined in this guide, you’ll be able to troubleshoot the problem and get your lawn mower back to its optimal condition.

Steps To Troubleshoot And Fix Smoking Lawn Mowers

Are you tired of your lawn mower emitting excessive smoke? A smoking lawn mower can be caused by a wide range of issues such as clogged air filters, corroded spark plugs, damaged piston rings, leaking fuel lines, and overfilled engine oil.

Luckily, these cases can be quickly identified and resolved without the need for professional help.

Inspection Of Affected Parts And Identification Of The Smoking Source

The first step towards resolving smoking lawn mowers is identifying the source of the smoke. Follow these steps:

  • Turn off the lawn mower engine and ensure it is cool before the inspection.
  • Loosen and remove the screws holding the air filter cover in place.
  • Check the air filter for blockages caused by dirt and debris.
  • Review the spark plug for corrosion or damage.
  • Inspect the muffler for damages, clogs, or excessive dirt.

Cleaning Of Clogged Air Filters And Corroded Spark Plugs

Clogged air filters and corroded spark plugs are common causes of smoking lawn mowers. Cleaning these parts can easily fix the issue. Follow these steps:

  • Remove the air filter cover and take out the filter.
  • Use water and mild soap to clean the filter until all dirt and debris are cleared.
  • Dry the filter and replace it accordingly.
  • For corroded spark plugs, use a wire brush to remove the corrosion and other dirt particles.

Replacement Of Leaking Fuel Lines And Overfilled Old Engine Oil

Leaking fuel lines and overfilled old engine oil can cause excess smoke emissions. Follow these steps:

  • Check for any visible cracks on the fuel lines.
  • Use a wrench to tighten any loose connections between the fuel lines and the carburetor.
  • For overfilled old engine oil, remove the oil using a siphon or dipstick and add new oil to the recommended level.

In addition, don’t forget to read: How Long Do Lawn Mower Batteries Last?

Repair Or Replacement Of Damaged Piston Rings

Damaged piston rings can cause smoking lawn mowers. The best solution is to get the rings repaired or replaced by a experienced mechanic.

Tightening Or Replacing Loose Or Broken Connections

Loose or broken connections can cause smoking lawn mowers. Ensure that all connections are tightened and any damaged ones are replaced accordingly.

By following these steps, you can easily troubleshoot and fix your smoking lawn mower, saving money and time in the process. Remember to regularly check and maintain your lawn mower to avoid regular issues.

Tips To Prevent Lawn Mowers From Smoking

Lawn mowers work hard to keep your lawn well-manicured throughout the year. With constant use, they can produce a smoking problem, which is not only unsightly but also a sign of an underlying problem. Here are some helpful tips to prevent lawn mowers from smoking:

Regular Maintenance Schedule

A well-maintained lawn mower is less likely to smoke. It is essential to follow a regular maintenance plan to keep your lawn mower running smoothly. Here are a few tasks you should do regularly:

  • Change oil and filter: Old engine oil can cause your lawn mower to smoke. Change the oil and filter according to the manufacturer’s instructions.
  • Replace spark plugs: A faulty spark plug can cause the engine to run rich, leading to smoke. Replace the spark plugs at least once per year.
  • Clean or replace air filter: A dirty air filter can limit airflow to the carburetor, leading to smoke. Clean or replace the filter according to the manufacturer’s instructions.

Also, make sure to read: How to Sharpen Lawn Mower Blades Without Removing

Proper Fuel And Oil Management

Using the wrong fuel or oil can also cause smoking in your lawn mower. Here are a few advice to ensure proper fuel and oil management:

  • Use the right fuel: Use fresh, unleaded gasoline with a minimum 87-octane rating. Don’t use gasoline with more than 10% ethanol.
  • Use the right oil: Use the oil recommended by the manufacturer for specific temperature ranges. Don’t overfill the oil and check the oil level before each use.
  • Drain old fuel: If your lawn mower has been sitting for several months, drain the old fuel before refueling.

Adequate Cleaning And Replacement Of Parts

A dirty or damaged lawn mower can also lead to smoking. Here are some tips to ensure good cleaning and replacement of parts:

  • Clean under the deck: Remove debris and grass clippings from under the tier regularly to prevent clogs.
  • Sharpen blades: Dull blades can cause your lawn mower to work harder and smoke. Sharpen blades at least once per year.
  • Replace damaged parts: Check your lawn mower regularly for worn or damaged parts and replace them as necessary.

Examination Of Lawn Mower Before And After Use

Before and after using your lawn mower, it’s essential to examine it thoroughly to ensure everything is working correctly. Here are some tips to keep in mind:

  • Check the oil and fuel levels before each use.
  • Inspect the spark plug and replace it if required.
  • Check the blades for signs of damage or wear.
  • After each use, remove debris from under the deck and clean the air filter.

By following these tips, you can keep your lawn mower running smoothly and prevent smoking. With routine maintenance and proper fuel and oil management, you can enjoy a well-manicured lawn free from smoke.

Read also: Are Lawn Mower Blades Reverse Thread?

Frequently Asked Questions On Why Is My Lawn Mower Smoking

Why Is My Lawn Mower Smoking Excessively?

If your lawn mower is smoking excessively, it could be due to an oil leak, the carburetor, or a clogged air filter. Check for these issues to reduce smoking.

How Do I Fix A Smoking Lawn Mower?

To fix a smoking lawn mower, start by checking the oil and air filter. Replace them if essential. If the issue persists, clean the carburetor and fuel lines.

Can Bad Gasoline Cause A Lawn Mower To Smoke?

Yes, bad gasoline can cause a lawn mower to smoke. Gasoline can go bad after a few weeks or months, causing carburetor issues and smoking.

How Often Should I Change The Oil In My Lawn Mower?

Change the oil in your lawn mower after every 50 hours of use or once per season. Fresh oil will keep your mower running smoothly and prevent smoking.

Why Is White Smoke Coming From My Lawn Mower?

White smoke from your lawn mower could be caused by burning oil, a dirty air filter, or any other issue that causes excessive smoke. Check the oil and filter and clean or replace them if necessary.


Your lawn mower is a vital tool in keeping your yard looking beautiful and well-kept. However, when it starts to smoke, it can be problematic and frustrating. Thankfully, there are several reasons why your lawn mower could be smoking, such as clogged air filters, old oil, or damaged components.

By determining the root cause of the issue and managing it promptly, you can prevent further damage and prolong the lifespan of your lawn mower. It is important to complete regular maintenance on your lawn mower to keep it functioning properly.

Overall, understanding why your lawn mower is smoking and taking action can save you money, time, and frustration in the long run. So, the next time you notice your lawn mower smoking, don’t panic! Take a deep breath, follow these tips, and get back to enjoying a well-groomed lawn.


  • David Mark

    David Mark is an experienced gardening guide with over 20 years of experience. He is passionate about helping people learn about gardening and creating beautiful, healthy gardens. David's love of gardening began at a young age, when he would help his parents in their backyard garden. He quickly learned the basics of gardening, and as he grew older, he began to experiment with different plants and techniques. After graduating from college, David worked as a landscaper for several years. This gave him the opportunity to work on a variety of different gardens, from small backyards to large commercial properties. He also learned how to install irrigation systems, build raised beds, and create patios and walkways. In 2005, David decided to start his own gardening website. He quickly became known for his expertise and friendly personality. He has helped hundreds of people create beautiful gardens, and he is always happy to share his knowledge with others. David is a certified Master Gardener, and he is a member of the American Society of Landscape Architects. He is also a regular contributor to gardening magazines and websites.

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