Skip to Content

How to stop a lawnmower from smoking. Troubleshoot & Fixes

On a beautiful sunny day, you plan to do some trimming or give your lawn a thorough cut. All goes wrong when you suddenly discover that your lawnmower is blowing smoke. Even so, stay calm. Typically, it is not so severe, and the issue can be easily fixed by some simple techniques mentioned in this article.

Blowing smoke is usually not a severe malfunction, but it can turn into something worse if it is not handled carefully. Do not panic! We have prepared a troubleshoot guide to progress gradually and carefully from one stage to the next. The primary cause for such havoc can be the leakage of oil into the exhaust, apart from other common issues.

How to stop a lawnmower from smoking:

  1. Inspect oil levels in the engine as exceeding the specified class would cause the engine to smoke.
  2. Endeavor always keeps the mower on balanced level ground as it would lessen the possibility of tilt and spilling of oil out of the mower.
  3. Use the engine oil grade that is suitable for your mower. You can get an idea of the type and amount from the lawnmower owner’s manual.
  4. Make sure that crankshafts are free of oil leakages.
  5. Ensure that the head gasket, rings, and cylinder are not damaged.
  6. Check and replace the air filter.
  7. Inspect the tilting angle of your mower’s engine as angles greater than 15 degrees make your engine smoke.

Common Causes of a Lawn Mower Smoke:

The probable cause is the oil spillage from the oil tank when you are changing the oil or filling it beyond the suggested level.  Additionally, turning/tilting the engine upside down during maintenance, storage, or any other reason can also contribute to this issue. When you are moving uphill or downhill, it can cause oil spillage. Other plausible causes include:

  • Overfilling the crankcase with oil
  • Any blockage in the breather tube which is located in the back of the air filter
  • Damaged crankcase breather
  • Blown head gasket
  • Damaged cylinder or rings
  • Use of wrong engine oil grades
  • An engine tilted at an angle which is greater than 15 degree
  • Air leaks from the crankcase

What matters the most is the color of smoke. It can be white, blue, or black. These colors indicate peace, depth & stability, power, and authority in an ideal world, respectively. However, these colored emissions have an entirely new meaning for lawnmower blowing smoke, and they could indicate troubling machinery. If you are not familiar with the mechanical components and do not precisely know where to troubleshoot from, this article can give you an insight on how to address the smoky lawnmower without consulting a professional.

White and blue smoke:

White and blue smoke indicates that the engine is burning oil due to some reason. Remain peaceful if your mower is smoking because it is not due to any complicated issue. Lawnmowers usually produce white or blue smoke when oil is overfilled, and it seeps into the crankcase. Damaged piston rings and low-quality oil are also reasons for the smoke.

Follow the given detailed steps to get rid of white and black smoke:

● Step 1. Check the level of oil:

Filling engine oil beyond the limit or using unsuitable engine oil grade can be a reason for both clouds of smoke. Follow the steps below to check the oil level.

  • Remove the stick after opening the dipstick cap
  • Please clean it
  • Then put it in the oil again
  • Oil level must be between two holes on the dipstick but if the oil is overfilled, use the owner’s manual to learn how to drain oil

● Step 2. Adjust the tilting angle:

Make sure that the tilting angle of the engine is less than 15 degrees. Mowing uphill can cause the oil to spill into the combustion chamber, so in this case, make sure that the spark plug is facing upward to avoid leaking of oil.

● Step 3. Inspect oil leakage in crankcase:

Examine the crankcase for leakages and seal them as soon as possible.

● Step 4. Use the right oil:

Always use the good quality oil and also inspect which grade oil is suiting your lawnmower. Never overfill the oil as it causes many issues.

● Step 5. Examine rings, cylinders, and head gasket:

Check if the rings, cylinders, and head gaskets are damaged. If so, replace them because they can’t be repaired.

An Important Tip: When you start a new mower, it gives white smoke. There is no need to worry because it is due to residue left behind in the mower by the manufacturer. In this case, just let the engine run until all the remainder is burned.

● Preventive measures:

Mostly thin white smoke disappears on its own by letting the engine run- as it is not a significant matter of concern. However, a much thicker white smoke can be a signal towards the big issue. For example, this issue may be because the oil made its way into the combustion chamber and then creates difficulty for the engine to work correctly. But on the positive side, such type of issues can be solved quickly. Oil is used to lubricate parts around the engine, but if you add more oil than recommended, it can seep into other parts where it shouldn’t be. When the mower is turned on engine starts making blue or white smoke by burning that seeped oil.  So, it is crucial to prevent oil spillage. Keep your spark plug in an upward position to avoid this issue even when moving uphill.

Black smoke:

Black smoke indicates that there is some issue in the carburetor and fuel system. It shows the burning of more fuel than air, i.e., the fuel mixture contains more gasoline than the required amount. It may be due to a faulty carburetor or debris stuck in the air filter. Black smoke in the lawnmower is due to debris in the air filter, causing clogging or an un-cleaned carburetor.

● Preventive measures:

  • Locate Air filters: First of all, locate the position of air filters.
  • Clean the air filters: After detaching using soap/detergent and water to clean them. Use an air gun if available to blow air for detailed cleaning. If the stuck dirt and debris are not cleaned, i.e., the air filter is clogged, replace it with a new one as they are not so expensive. (paper filters cannot be cleaned; they can only be replaced).
  • Fix the air filters: Now test the mower. If it is still smoking (black smoke), then follow the next step, and if not, you are good to go.
  • Adjust the carb: Consult the owner’s manual to adjust the carburetor by twisting the screw. Adjusting the carburetor would make a balanced flue-air mixture. Check again and adjust the carburetor to make a leaner mixture if the black smoke persists.
  • Inspect the choke and reinstall: The air-fuel mixture would be rich in gasoline if the choke is facing some problem. So, inspect the choke’s connection, check if it requires repairing, and ensure it is free of grime and debris. Consult the manual for adjustment purposes. Usually, there are two screws on the unit’s outer side, one for the idle and the other for the fuel mixture.

If the lawnmower continues to produce black smoke after following the above steps, some complicated issues should be addressed to professionals.

Excessive smoke:

If after following the above-explained steps, it shows that oil reaches the combustion chamber through some worn or damaged seals, and it can make the engine dead, which is a severe issue. This issue can be due to:

The piston ring avoids the movement of oil between cylinder and piston wall, and if it’s broken or damaged, it would indeed cause smoke. Usually, three pistons are used in a lawnmower engine.

  • Compression ring: The first one is a compression ring that blocks the piston’s heat to move in the crankcase. It removes excess oil from the cylinder wall by rubbing it so the excess oil does not seep into the combustion chamber.
  • Middle ring: The middle ring wipes oil and moves it to the crankcase to end the possibility of oil moving into the combustion chamber, therefore called a wiper ring.
  • Third ring: The third and the last ring control the oil application on the cylinder wall and is called an oil ring.

If any of the three rings are damaged or worn, it results in oil spillage from the cylinder to the combustion chamber, where it burns and produces white smoke. Damaged or faulty air and fuel filters would allow the dust and debris into piston rings, damaging them.

Frequently Asked Questions:

1. Why oil comes out of the lawnmower exhaust?

When the mower is started, fuel with oxygen moves into the piston through the valves, and exhaust gases are forced out. But if any one of the components in the piston, cylinder, exhaust pipe, and exhaust manifold is damaged, it would cause the oil (used for lubrication around the engine) to come out of the exhaust. Some common causes of oil coming out of the lawnmower exhaust are:

  • Clogging in the oil filter
  • Damaged piston ring
  • Damaged valves
  • Cracked engine block
  • Blown head gaskets
  • Tilted lawnmower greater than the angle of 15 degrees
  • Overfilling of oil

2. When the lawnmower blows blue smoke?

Engine oil is used to lubricate the engine, but the combustion chamber must be free of that oil for the sake of clean fuel burning. But if the engine seeps into the combustion chamber, it burns with the fuel, resulting in blue smoke that passes through the exhaust system. Some causes of blue smoke are:

  • Worn engine oil seal
  • Worn piston rings
  • Worn valve seals
  • Non-functioning PCV valve
  • Intake gasket leak

3. How to drain oil from lawnmower?

Place the mower on a level horizontal surface and locate the drainpipe at the bottom of the lawnmower’s engine. Take any container in which you want to collect the drained oil and place it on the ground near the mower. Use an adjustable wrench to remove the drain’s cover and let the old oil drain in the container placed at the ground. In some cases, the drainpipe has a valve, and we are supposed to turn the valve cap on for draining purposes. After draining the oil, fix the cover or turn the valve cap to stop the process.

Final Remarks:

Engines of different mowers are designed differently, so you must consult the owner’s manual before proceeding and applying any of the above procedures and maintenance hacks. Safety comes first, so use the right protective gear before undertaking any hack or technique. Consult a professional if the engine does not stop smoking after adopting the above steps as engine producing smoke and failure of the engine to start are the signs of fundamental engine problems, which would result in the breakdown of the whole system.

Leave a comment

We try to answer each comment, but please read our comment rules first here. Use an existing and correct email address as you will receive an verification email. Your email address will not be published. All fields are required.

  1. Charles Carlson says:

    Is it safe to continue using the lawnmower if it is blowing smoke, or should I immediately stop and address the problem?

    • Allard Vdhooft says:

      It’s best to address the issue early on to prevent further damage. Check oil levels, inspect for leaks, and use the correct oil grade to resolve the problem with your lawnmower blowing smoke.

  2. Paul Mckinney says:

    Can using the wrong engine oil grade cause long-term damage to the lawnmower’s engine?

    • Allard Vdhooft says:

      Using the wrong engine oil grade in a lawnmower can indeed cause long-term damage to the engine, so always ensure you are using the recommended grade. Good luck with your troubleshooting!

  3. Nelson Walters says:

    How can we know if the spark plug in the lawnmower is facing upward to prevent oil spillage?

    • Allard Vdhooft says:

      To prevent oil spillage in your lawnmower, ensure the spark plug is facing upward when moving uphill, adhere to the oil grade specified in the manual, and always maintain the mower on level ground. Happy mowing!

  4. Carmen Nelson says:

    What are the consequences if the lawnmower continues to smoke even after trying these steps?

    • Allard Vdhooft says:

      If your lawnmower continues to smoke after trying these steps, consult a professional to address any severe issues that may be present. It’s always better to be safe than sorry.

  5. Barry Morrison says:

    Thank you for highlighting the importance of using the right engine oil grade. I will make sure to check this for my lawnmower.

    • Allard Vdhooft says:

      Barry, I’m glad you found the information helpful. Remember to always use the right engine oil grade for your lawnmower to prevent smoke issues. Happy mowing!

  6. Erika Lambert says:

    How can we ensure that the rings, cylinders, and head gasket in the lawnmower are not damaged and causing smoke?

    • Allard Vdhooft says:

      Hi Erika, make sure to check oil levels, engine tilting, and the condition of the head gasket, rings, and cylinders. These factors can contribute to smoke in the lawnmower.

  7. Justin Rodriquez says:

    I wonder if there are any signs we should look out for to identify if the issue is getting more severe?

    • Allard Vdhooft says:

      Thank you for your question, Justin. Signs of a more severe issue may include thicker smoke, oil leakage, or engine misfiring. Follow the guide provided in the article to troubleshoot step by step.

  8. Lucy Banks says:

    How do we know if the head gasket in our lawnmower is blown and causing smoke?

    • Allard Vdhooft says:

      Lucy, follow the steps in the article to troubleshoot your lawnmower smoke issue. It’s likely a simple fix related to oil levels, tilting angle, or oil type. Stay calm and follow the guide step by step.

  9. Mae Green says:

    I found the troubleshooting steps for white and blue smoke very practical. It’s good to know that some issues can be easily resolved by following these instructions.

    • Allard Vdhooft says:

      Thank you for your positive feedback, Mae Green! I am glad you found the troubleshooting steps helpful in resolving the smoke issues with your lawnmower. Stay calm and keep mowing!

  10. Sue Lawrence says:

    This article gives great step-by-step guidance on stopping lawnmower smoke. I feel more confident now in handling this issue. Great information for beginners like me!

    • Allard Vdhooft says:

      Thank you, Sue! I’m glad you found the article helpful in addressing lawnmower smoke issues. Happy mowing!

  11. Tracey Kennedy says:

    Very informative and detailed steps provided for troubleshooting lawnmower smoke. Thank you for breaking it down into easy-to-follow instructions.

    • Allard Vdhooft says:

      I’m glad you found the troubleshooting steps helpful! Remember to always refer to the owner’s manual for specific guidance. Happy mowing!

  12. Johnni Hernandez says:

    I never knew that the tilting angle of the lawnmower could affect oil spillage and smoke. Very interesting information!

    • Allard Vdhooft says:

      Thank you for your feedback, Johnni! I’m glad you found the information interesting. Let me know if you have any other questions related to lawnmower maintenance.

  13. Kim Ruiz says:

    The video demonstrations in the article were very helpful. Are there more resources like this to learn about lawnmower maintenance?

    • Allard Vdhooft says:

      Thank you for your feedback! I’m glad you found the video demonstrations helpful. You can check out more resources on lawnmower maintenance by exploring our blog further.

  14. Max Diaz says:

    I appreciate the detailed explanation on the roles of different piston rings and how they can cause smoke issues in the lawnmower.

    • Allard Vdhooft says:

      Thank you for your detailed explanation of the causes of lawnmower smoke issues. I’m glad you found the information helpful. Good luck with fixing your lawnmower!

  15. Genesis Johnston says:

    I appreciate the preventive measures mentioned to avoid lawnmower smoke issues in the future. It’s great to know how to prevent these problems from happening.

    • Allard Vdhooft says:

      Thank you, Genesis! I’m glad you found the preventive measures helpful in avoiding lawnmower smoke issues. Remember to follow the troubleshooting guide step by step for a quick and easy fix.

  16. Alan Wood says:

    Thank you for explaining the different colors of smoke and their meanings. It helps in identifying the root cause of the issue.

    • Allard Vdhooft says:

      Thank you for reading our article on identifying the root cause of smoke in a lawnmower. We’re glad you found it helpful!

  17. Clarence Cox says:

    Is it possible to fix the carburetor and fuel system issues causing black smoke on our own?

    • Allard Vdhooft says:

      It’s best to have a professional assess issues with the carburetor and fuel system causing black smoke from your lawnmower to ensure a proper fix and prevent further damage.

  18. Clifton Cruz says:

    How often should we check the oil levels in the engine to prevent smoke issues?

    • Allard Vdhooft says:

      Checking the oil levels once a month is ideal to prevent smoke issues in your lawnmower. Maintain a balanced level ground when mowing. Follow the steps in the article to troubleshoot any smoke problems.

  19. Marion Pierce says:

    The article was a great read for someone like me who is not very familiar with lawnmower mechanics. It provided a comprehensive guide to address smoke issues effectively.

    • Allard Vdhooft says:

      Thank you, Marion! I’m glad you found the article helpful in addressing lawnmower smoke issues. Let me know if you have any other questions or need further assistance.

  20. Everett Hicks says:

    What should be our next steps if we detect black smoke coming from the lawnmower?

    • Allard Vdhooft says:

      It’s best to first check the oil level, ensure the mower is on level ground, and inspect the engine components for damage when black smoke is detected. Slowly progress from one step to the next.