Lawn Mower White Smoke (How to Stop and 4 Steps for Fix)

When you are mowing your lawn, you can expect to see grass clippings go flying—but the last thing you might anticipate is for your machine to start billowing smoke. In a matter of moments, your peaceful afternoon of yard maintenance can turn into a coughing fit amid a smoke plume.

Unfortunately, gas-powered lawn mowers tend to be full of surprises, including a variety of smoke expulsions for different reasons. Whether your mower starts smoking halfway across the lawn, or it begins the second you try to start the unit, lawn mowers are known to blow smoke during their lifespan.

So, what is your lawn mower white smoke and how bad is it?

Thankfully, there is no need to panic yet! Read on for the steps to take to handle a smoking lawn mower and what learn could possibly be causing it, as well as some other common colors of smoke you might encounter.

What Is Lawn Mower White Smoke?

Though it can be an alarming sight, lawn mower white smoke is typically harmless and easily solved. In most cases, that visible white smoke is simply the burnoff of oil that has come into contact with the unit’s engine itself, like food residue burning off the bottom of a cooking pan when placed on the stove.

This happens when the unit has been tipped over or oil has been spilled during refilling, and now the engine is trying to burn it off, resulting in lawn mower white smoke.

Lawn Mower start to smoke

What Does Smoke From Your Lawn Mower Mean?

Though lawn mower white smoke typically is caused by oil spillage, other factors can contribute to that type of smoke, and other common colors that you might notice billowing from your lawn mower. Let’s discuss these a little further and delve into the possibilities.

Why Is My Lawn Mower Blowing White Smoke?

As previously mentioned, lawn mower white smoke is commonly a sign of oil spillage onto the engine and is usually nothing particularly serious. Oil is sloshed onto the engine by making a mistake when refilling the adjacent oil tank, by having a dirty oil filter, or a leaky muffler.

Alternatively, lawn mower white smoke can be caused by the unit being tipped over and oil escaping the tank due to gravity. Thus, it is important to never store your lawn mower on its side or upside down during its season of use.

Additionally, if you perform maintenance on the lawn mower and have to tip it on its side, make sure all oil spillage has been cleaned up before powering the unit up again.

Or, if you have a particularly steep lawn, this can cause the oil tank to tip just enough for the liquid to slip out and hit the engine. This is more common on lawns that have an incline of over 15 degrees, where the lawn mower needs to function on a sustained angle in order to mow the grass and the oil tends to leak over and into the engine.

But in some cases, lawn mower white smoke can be a sign of a defective crankcase breather, a blown head gasket, or even a faulty carburetor. Make sure to check for all these possible flaws before starting up your lawn mower again.

Why Is My Lawn Mower Blowing Blue Smoke?

Another common smoke color for lawn mowers to start emitting is a plume of blue. This particular smoke can indicate a couple of things wrong with your lawn mower that are similar to the causes of lawn mower white smoke. That includes oil overfilling the crankcase and spilling within the machine’s engine.

Blue smoke can also occur when the wrong oil grade has been used in the oil tank, so make sure the oil type is appropriate for the lawn mower you have. Additionally, the spark plug could be tilted too far back to accommodate a greatly slanted lawn, and could be causing the blue smoke.

However, most blue smoke is the sign of something bad happening within the engine or fuel tanks, and you might need a professional’s help to get it fixed.

Why Is My Lawn Mower Blowing Black Smoke?

Black smoke might seem like the end of the world, but in reality, black smoke coming from your lawn mower can just be a sign of a faulty fuel system. In most instances, lawn mowers that billow black smoke need to have their carburetors, filters, or fuel lines checked and possibly recalibrated.

Because these systems are the ones that regulate gas to air and power the entire engine, any issues with them will end up with a poor gas ratio and black smoke coming out of your lawn mower.

Alternatively, black smoke can be a sign of the air filter needing to be cleaned or replaced. Once an air filter is clogged, the engine receives too much unregulated gasoline and will start to blow black smoke.

This can be dangerous to the engine if you don’t solve the smoke problem immediately, as higher carbon levels can harm the rest of the lawn mower.

The solution is to either clean or unclog the air filter if it is dirty and full of debris or, if there has been too much damage caused, simply replacing it altogether. Luckily, air filters are cheap to find at your local hardware store and easy to replace by yourself.

Lawn Mower White Smoke: Quick Steps

So, your lawn mower is busy billowing white smoke in the middle of the yard—what should you do? While many causes of smoke can be fixed at home, it’s possible that your machine has a problem that requires a professional’s help. You should check it over first though, as it could be something simple.

Lawn Mower fix steps

  • Step One—Turn off the lawn mower immediately and leave it to rest before examining it further. Then, once it has cooled down sufficiently and safely, open the top of the chassis to inspect the inner workings.
  • Step Two—Find and check the air filter. It is generally near the top of the engine, fitted in a plastic case. The air filter might need to be cleaned or replaced if dirty.
  • Step Three—Check the lawn mower’s oil. This includes the level in the tank, the grade, and the type. Try changing the oil if it’s low, or replacing the oil if it’s the wrong type for the lawn mower.
  • Step Four—Review the angle you were mowing at and make sure it was no greater than 15 degrees, as this can cause the engine to spill and smoke.

Final Thoughts

In the middle of mowing your yard, lawn mower white smoke is likely the last thing you want to deal with. But luckily, even if your unit is billowing smoke, the underlying problem might not be detrimental and probably only requires some cleanup or replacing a filter.

So, if your lawn mower starts smoking, it’s best to turn it off and not panic—fixing the problem yourself is generally doable and you can be back to mowing the yard in no time!


How Do I Fix White Smoke From My Lawn Mower?

Lawn mower white smoke is typically the sign of spilled oil that is burning on the engine. This is a harmless issue, and you can actually let the lawn mower run until the oil has burned off completely if this is the case.
However, white smoke can also be caused by some more serious issues, like filter or calibration problems. If this is the case, shutting off the smoking lawn mower and then investigating the issue further once it has cooled is advised. You might need to replace the oil or clean out other parts of the engine.

What Would Cause A Lawn Mower To Smoke?

A variety of things might cause your lawn mower to smoke, including issues with the oil, air filter, fuel lines, or even simply the angle at which you are mowing your graded lawn.
If spilled oil is not the cause of your smoking lawn mower even though it’s the most common issue, the engine might be getting fuel that is not mixed with enough air, and is thus too carbon-rich.

What Happens If I Put Too Much Oil In My Lawn Mower?

If you put too much oil in your lawn mower, it will likely start to blow white smoke as soon as you turn it on, unless the excess oil has been cleaned up thoroughly. This is because the excess oil will not be able to spread to an area of the engine where it’s used, and instead will coat the outside of the heated engine block and cause burning.
While this is not the end of the world for a lawn mower, it’s important to not overfill the oil tank in your lawn mower, and to clean up any spills as soon as they happen to avoid the plumes of smoke that can result from burning oil.
too much oil in lawn mower

Can A Lawn Mower Explode?

The short answer is that yes, a lawn mower can indeed explode, if the conditions are right. While a lawn mower is unlikely to explode because it is blowing white or any other color of smoke, it’s also important not to ignore the warning signs when they occur.
A lawn mower can explode if it catches on fire due to the mixture of flammable oil and explosive gasoline surrounding the engine. And though instances of exploding lawn mowers are uncommon, and lawn mower white smoke is not a direct indication of that, it’s wise to keep your unit well maintained and working smoothly.

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