White Smoke From Lawn Mower: What it Means and How to Fix

Is your lawnmower emitting different color smoke? Wondering what the smoke from your lawnmower signifies and how to address it? No need to panic! 

Quick Answer

In my experience, smoke from lawn mowers typically arises from either a dirty air filter, spilled or excessive oil, or using the wrong oil grade. All of which have straightforward solutions. 

Keep reading below to learn what each color smoke means and what you can do to fix the issue.

how to stop a lawn mower from smoking
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Quick Troubleshooting Steps

  • First, check the air filter and replace it if it is dirty.
  • Next, check the oil level. Fill with proper oil grade if necessary.
  • Then start the mower and let it run for 5-10 minutes to burn off any oil that may have found its way to the engine.
  • Also, mowing at step angles for a long period could cause smoke as there could be oil leakage. Make sure caps are fully secure.

Keep reading for different smoke colors as each has its own set of issues.

Smoke from lawnmowers is typically one of 3 colors:

  • Black Smoke
  • White Smoke
  • Blue Smoke

I’ll go over each color below along with some suggested solutions you can try right now and possibly avoid a trip to the lawn mower repair shop.

What does Black Lawn Mower Smoke Mean? 

black smoke from a lawn mower

Black smoke from your lawn mower in most cases means your carburetor and fuel systems aren’t functioning properly. These aforementioned systems are responsible for regulating the ratio of gasoline to air mixture, and when the carburetor doesn’t get enough air, the fuel mixture will be too rich, resulting in a higher percentage of gasoline. 

Black smoke coming out of a lawn mower means that the ratio of fuel to air is incorrect, which is usually caused by a dirty or worn-out air filter. To clean the air filter of the lawn mower, remove it and clean it with soapy water or replace it with a new one by referring to your owner’s manual. 

Solution for Black Lawn Mower Smoke

If your lawn mower is creating black exhaust smoke, the first thing you’d want to check is the onsite air filter. Great chances are that the air filter may be clogged, and is blocking sufficient airflow to the carburetor. 

Since all models vary by brand, it’s important that you refer to your owner’s manual on how to clean the air filter. But generally, you have to remove it, clean it, or replace it if it’s damaged. 

After you’ve cleaned or replaced the air filter, start your lawn mower, and let it run for a few minutes to see if the issue has been fixed.

If the black smoke issue still persists after cleaning or replacing the air filter, then it may be your carburetor acting up, so you will have to make a couple of adjustments. 

Even though this step is just a matter of adjusting a screw or two by referring to your owner’s manual, your best bet is to have it looked at by a professional or better yet the manufacturer if your lawn mower is still under warranty.

What does White Lawn Mower Smoke Mean? 

white smoke from a lawn mower

White is the most common color of lawn mower smoke, and most of the time will go away on its own. But if it doesn’t, there’s a good indication that you’ve got an overfull oil reservoir. An overfull oil reservoir will cause the engine to burn oil, which can be caused by one or more reasons. 

These include spilling oil on the housing when you serviced the lawn mower and tilted it too much, or simply overfilling the crankcase. 

An overfull lawn mower oil reservoir can also be caused if you mowed on a 15-degree incline, overfilled the gas tank if you have a 2-stroke mower (the correct ratio is 32:1 gasoline to oil ratio), or it’s a new mower with leftover oil residue. 

See also my article on the type of gas to use for your lawn mower.

Solution for White Lawn Mower Smoke

As mentioned earlier, the white smoke issue will go away on its own if you leave the lawn mover running for a few minutes, as this runtime will burn off the excess oil. If the white smoke isn’t gone after running your lawnmower for roughly 15 minutes or so, you may have a bigger issue to deal with.

The first issue may be that the seals of the combustion chamber have worn out, causing the oil to leak into it. Another reason may be an air leak in the crankcase, or the cylinder and rings have worn out. 

A serious reason for white lawn mower smoke will pertain to a malfunction of the head gasket, and will more than likely need professional attention. However, there’s no need to break a sweat just yet but check if your lawn mower is still under warranty, and if it is, get it looked at by your nearest servicing dealer. 

What does Blue Lawn Mower Smoke Mean? 

blue smoke from a lawn mower

The causes of blue smoke emitting from the exhaust of your lawn mower are pretty much the same as white smoke. These include overfilling the crankcase, or spilling oil on other parts of the mower when filling the crankcase. 

Blue smoke can also be caused if using the wrong oil grade, or if you’ve tilted the lawn mower too much when mowing a ditch or hill, so make sure to keep the spark plug tilted if angled mowing is necessary.  

Here is a great video from Steve’s Small Engine Saloon

WOW!! You Won't Believe What's Wrong With This Lawn Mower

Final Thoughts

Having a smoking lawn mower is never fun for the operator or for your neighbors, so addressing any smoking issues you have when you first notice it is key. It will help your mower last much longer plus your neighbors and your lungs will thank you.

You may also want to opt for non-gas mowers such as reel mowers or corded electric mowers.

If you have any specific questions about your mower, please leave a comment or question below.

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