Why Is My Lawnmower Smoking?

It’s hard to find time for mowing in the first place, so when the lawnmower starts smoking, it’s easy to get discouraged. Luckily, it’s usually pretty easy to diagnose, and the most common problems can be simple to fix.

“First and foremost, if your mower begins smoking after starting, turn it off immediately,” says Shawn Carothers, a manager at Toro. “While seeing smoke can be alarming, taking immediate action to diagnose the issue will help you avoid any serious problems.”

Here’s how to troubleshoot why your lawnmower is smoking, and the next steps to take.

Why Is My Lawnmower Smoking?

Here are the most common causes behind a lawnmower smoking.

Blocked Air Filter

A dirty or clogged air filter is one of the most common causes of a lawnmower smoking. “You’ll know that this is the cause if your mower is smoking black, which means that it has too much fuel and not enough air is getting in,” says Ionel Giuran, a lawn care expert with Fantastic Gardeners.

Leaking Oil

If your mower is blowing out white or blue smoke, it probably means oil has gotten into somewhere it’s not supposed to be, such as the engine. “This can happen because you’ve recently turned it to its side to change the blades or because you’ve overfilled it,” says Giuran.

Larger Issues

While a lawnmower smoking is most often caused by one of the above issues, it can also be due to a more serious problem, such as a carburetor that needs adjusting or worn-out engine components and seals.

Electric Motor

If your electric lawnmower is smoking, it could be that the motor has burned out or the belt or another element is overheating, says Giuran. “If you’re not exactly sure which one’s the reason for the smoke after careful examination, it’ll be safest to call and consult with a repair specialist.”

How to Fix a Smoking Lawnmower

Turn off the engine immediately when you see smoke, and let the machine cool down. Clean or replace the air filter and wipe away any oil residue from lawnmower parts. If the oil reservoir is overfilled, drain out a bit of the oil, and also consult your owner’s manual to make sure you used the correct oil. Check for leaky gaskets and seals. If none of this works, it could be that your engine components are worn out.

“This may be the hardest to fix,” says Carothers. “Some worn-out engine parts can be replaced at home, but Toro recommends seeking out a dealer to determine the extent of the engine concerns.”

Troubleshooting Why Your Lawnmower Is Smoking

Start by looking for common issues listed above, like checking the oil levels and cleaning the air filter. If that doesn’t clear up the smoke, the mower may be damaged. “In most cases, the color of the smoke can help you start diagnosing the underlying issue,” says Carothers.

Colors of Lawnmower Smoke & What They Mean

• White: burning oil, possibly due to overfilling the oil reservoir.
• Blue: burning oil, possibly within the engine.
• Black: poor fuel mixture (too much fuel and not enough air), possibly from a dirty air filter, maladjusted carburetor or poor-quality fuel.

“Black is the worst of the smokes,” says Kody Ketterling, lawn expert and founder of K-IT Products. “A lot of times, the black smoke means you need to take it to a mechanic to be corrected or fixed. A head gasket may be blown, or a cylinder or rod is out.”

Location of Smoke

Smoke typically comes out of the exhaust system. “If it is black, you can find it coming out of where the issue may be,” says Ketterling. “For example, if you have bad seals, the smoke can leak out of those areas.”

When to Call a Pro

Consulting a pro, such as taking it to the dealer, may be the way to go if your mower is still smoking after following the troubleshooting steps, if the fix involves dismantling the mower or if your mower is still under warranty.

“Not all lawn care companies will be able to help with repairs,” says Taylor Olberding, co-owner of Heroes Lawn Care. “That surprises a lot of people, so make sure you contact someone with the right experience.”

Tips to Avoid a Smoking Lawnmower

Don’t overfill the oil, ensure you’re using the correct oil and don’t tip the mower on its side. Then, regular maintenance is the best way to prevent your lawnmower from smoking, and can help you find small issues before they get more serious. Regular lawnmower maintenance includes:

• Cleaning and replacing the air filter
• Checking oil levels regularly
• Changing the oil regularly
• Following other manufacturer-recommended maintenance

“We find that if mowers are stored correctly and kept out of the elements, this will keep your mowers in good shape,” says Ketterling. “Make sure you are sharpening the blades so the mower doesn’t have to work harder than it needs to with the sharp blades.”

FAQ

How long do lawnmowers last?

How long a lawnmower lasts depends on:

• How often it’s used and for what sort of jobs
• The quality of the model
• How well it’s maintained, stored, cleaned and serviced

“If looked after well and it is a decent model, it could last up to 20 years,” says Olberding.

Is a smoking lawnmower ever normal/OK?

Small bursts of smoke when starting the mower or operating on a hillside shouldn’t raise any alarms, says Carothers. But “if smoke continues to pour out or there is a large plume of smoke, there is likely a more serious issue that needs fixing,” she says.

About the Experts

Shawn Carothers is a Senior Marketing Manager at Toro and oversees the parts department for its residential and landscape division. She’s passionate about making sure customers are caring for their mowers throughout the year — especially during Toro’s Lawn Mower Maintenance Week — and ensuring they have access to all the tools necessary to do so, including the Toro yardcare blog.

Taylor Olberding is co-owner of Heroes Lawn Care in Omaha, Nebraska. He has a degree in turf and landscape management from the University of Nebraska and a deep passion for the science and implementation behind healthy lawns.

Ionel Giuran has been a lawn care expert with Fantastic Gardeners for more than eight years. From trees to grass, he has a passion for transforming landscapes into vibrant green outdoor spaces.

Kody J. Ketterling is owner of KJ lawn Maintenance & Spraying in Twin Falls, Idaho, and founder of K-IT Products. He has more than 25 years of experience in lawn and garden maintenance.