What To Do When Your Lawn Mower Is Smoking

What To Do When Your Lawn Mower Is Smoking

Most homeowners who regularly mow their lawn will eventually notice their machine emitting smoke at some point. If you’re not in this category, it’s normal to feel frightened at first. However, most of the time, a smoking lawn mower isn’t a serious problem and can be fixed easily.

First, it’s critical to determine what’s causing your lawnmower to smoke. After identifying the issue, you’ll need to follow a few steps to fix the issue. Continue reading as we discuss why your lawn mower is smoking and outline quick fixes to get your machine in working order. 

Causes of a Smoking Lawn Mower

Lawnmower smoke can be white, black, or blue. Each type of smoke has its own set of triggers, and each requires a different treatment. White smoke is produced when the engine is burning oil that enters the engine.

White smoke is produced when the engine is burning oil that enters the engine.

Black smoke is typically produced when the fuel is not completely combusted, and some of it condenses into black smoke. The problem could be with the spark plug and air filter. 

Lastly, blue smoke is frequently caused by an oil spill or a tilted engine while in operation. Let’s break down more possible causes below and discuss fixes.

Possible reasons for a White Smoke exhaust from a Lawnmower

1. Faulty Head Gasket

White smoke from lawn mowers is frequently caused by a faulty head gasket. Your lawn mower blowing white smoke is caused by coolant and oil seeping into the combustion chamber.

How to fix it: A faulty head gasket will require replacing. First, inspect the gasket. If it looks good, you can use sealant paste to prevent oil leakages and check how your machine works afterward. However, this is only a temporary fix. It is always preferable to replace the head gasket. However, if you are not confident with these complex repairs, we recommend taking your machine to a repairer.

Possible reasons for black smoke being emitted from your lawnmower

1. Incomplete fuel combustion

The main reason your machine discharges black smoke is that the fuel is not properly combusted. It is crucial to understand that the complete combustion of smoke is required for the proper functioning of the lawn mower engine. The air-fuel combination formed in the engine may be too rich in fuel and lacks sufficient air to completely burn the fuel. As a result, any fuel that doesn’t completely burn in the engine’s combustion chamber will cause black smoke. 

How to fix it: If your lawn mower’s black smoke is caused by incomplete fuel combustion, the problem is the machine’s carburettor. Therefore, cleaning or replacing the carburettor should resolve this issue. A carburettor creates a proper air-fuel mixture that the engine can use. This is why an issue with your carburettor may result in black smoke.

You can also try adjusting the carburetor before replacing it. Luckily, it is not difficult to adjust the carburetor so that the air-fuel mixture is properly proportioned. You can start by adjusting the carburetor and checking if the issue persists.  If adjusting the carburetor doesn’t help, cleaning it with a carburetor cleaner or replacing it will be best.

2. Dirty air filter

A dirty air filter could also be the reason for black smoke from lawn mowers. An air filter protects the engine from dirt and debris that may affect the operation. After a while, the air filter can get clogged, which means your lawn mower’s engine will not receive much-needed air. 

How to fix it: This issue is simple to resolve. If the air filter is foam, simply remove it and wash it with soap and water. If it is too dirty to be cleaned, replace the air filter. However, if it is a paper filter, discard it and buy a replacement. 

3. Dirty spark plug

If your lawn mower is emitting black smoke and refuses to start, the problem is most likely the spark plug. A spark plug ignites the fuel-air mix in the combustion chamber, and a dirty or faulty spark plug means there will be poor or incomplete ignition.

How to fix it: Remove the spark plug and clean the terminals to remove any carbon deposits. You can use a wire brush or sandpaper to clean it. However, if the carbon deposits are too difficult to clean or a component appears broken, we recommend replacing them. 

Possible reasons for blue smoke being emitted from your lawnmower

Proper maintenance ensures your lawnmower functions well for a long time. If your lawnmower is not properly maintained, smoking will become a regular occurrence.  Here are a few pointers to keep your lawnmower from smoking.

1. Excess oil

Blue smoke from lawn mowers is produced when oil is overfilled. So, check the oil level in the engine on a dipstick if you notice your engine is emitting blue smoke. If the oil level is too high, adjust it to the proper level. Too much oil in your machine will cause oil leakage and cause combustion outside the engine, leading to blue smoke.

How to fix it: Luckily, a lawn mower blowing blue smoke is usually easy to fix. Dip the dipstick into the oil tank to gauge the oil level. If the oil level exceeds the maximum limit on the dipstick, drain a portion of the oil. 

2. Slanted machine

If your machine is operating on slanted terrain, it can also result in blue smoke. This occurs because oil can enter the cylinder while the machine is slanted. Luckily, if blue smoke comes out of your lawnmower after it has been on steep terrain, it’s most likely a minor problem.

How to fix it: This issue is easy to fix. Allow the lawnmower to run on a leveled area for a while. If the angle was the cause of the blue smoke, the blue smoke should dissipate after a while. 

Lawn Mower Maintenance Tips

Proper maintenance ensures your lawnmower functions well for a long time. If your lawnmower is not properly maintained, smoking will become a regular occurrence.  Here are a few pointers to keep your lawnmower from smoking.

1. Regularly inspect the air filter

It is essential to regularly clean the air filter to prevent it from clogging. Furthermore, replace the air filter when needed. 

2. Regularly check the oil level

Oil is among the factors that contribute to a smoking lawnmower. For this reason, check your machine’s oil level regularly and top up as needed. Remember, don’t overfill the oil tank.

3. Regularly examine the muffler and exhaust system

Our final maintenance tip is to examine your machine’s muffler and exhaust system for any damage or blockage.

4. Change the spark plugs

Your spark plug will likely develop carbon buildup after some use. For this reason, it is important to change the machine’s spark plugs once every few months to ensure your machine keeps working well. 


Your lawnmower smoking can be puzzling if you don’t know what to do. Fortunately, this guide has highlighted fixes to ensure you know what to do when your lawn mower is smoking. Remember, because the engines of different lawnmowers are designed differently, you must consult the owner’s manual before proceeding with any of the procedures we discussed.

Furthermore, ensure you wear the appropriate protective gear, such as gloves and goggles, before attempting any fix. Also, feel free to consult a professional repairer if none of these fixes resolve the smoking issue. This may signify a bigger issue that may seriously damage your machine.

Frequently Asked Questions

1. How do I drain the oil from my lawnmower?

First, place the lawnmower on a level horizontal surface, and look for the drainpipe underneath the engine. Then, place a container beneath to collect the drained oil. Remove the drain cover and allow the oil to drain into the container. If the drainpipe has a valve, turn the valve cap to drain the oil. Then, turn the valve cap when you’re done draining oil.

2. Is the smoke from my lawn mower damaging?

In a nutshell, yes. The smoke from your lawnmowers can damage your machine. And if your lawn mower has issues that cause oil to burn, it’s a clear indication that there may be an underlying issue. Oil can also damage other parts of your lawnmower, such as the spark plugs, air filter, and other parts that aren’t designed to be in contact with oil. 

Although some issues that cause white or blue smoke will not harm your mower, you should investigate if you notice smoke on your lawnmower. If your lawn mower emits black smoke, you’re probably dealing with another issue.

3. How do I sharpen my lawnmower blades?

Blunt mower blades result in uneven lawns that appear frayed or torn rather than cut. If the blades need to be replaced, you’ll notice dents on them. Ensure you wear thick gloves and protective eyewear when sharpening these blades.

You can use a blade sharpener, bench grinder, or angle grinder to sharpen the blades. Remove the spark plugs and empty the fuel tank to avoid leaks and combustion risks. Afterwards, turn the mower on its side and locate the nut holding the blades in place. Loosen the nut and detach the blades. This article will provide a more detailed guide on how to sharpen your lawnmower blades