Why Is White Smoke Coming From My Lawn Mower Engine?

If you’ve ever noticed your lawn mower engine smoking, you’re not alone.

This is a common problem many people experience.

There are several reasons why your lawn mower engine might be smoking…

…And today we’re going to go through them all and tell you how to fix the problem.

First, you’ll see a quick-guide and then you will see an in-depth guide.

How To Stop Your Lawn Mower Smoking:

  1. Don’t over fill with oil. A common cause of your lawn mower blowing white smoke is too much oil and it getting into areas it should not be. Drain oil until and use dipstick to make sure it is not over filled.
  2. Don’t tilt your lawn mower air filter side down (always have the air filter facing up). If you tilt the mower air filter down oil will get in the filter and when in use the hot air exiting through the filter will start smoking.
  3. Fix your broken carburetor. Is fuel dripping from the carb? If you notice leaking from the carburetor – replace it.
  4. You may have a failed head gasket. This will require disassembly to check so you may need a professional.

Watch this video:

The Possible Causes Of Smoke From A Lawn Mower Engine:

Lawn mower engines are typically small, four-stroke engines. The oil is used to lubricate the engine’s moving parts, and the gasoline is combusted to power the engine. Blue or white smoke from a lawn mower engine can have several different causes. Let’s take a look.

Oil Is Where It Shouldn’t Be Will Cause White Smoke

  • Either someone has put too much oil in the engine and it is overflowing.
  • Or someone has tipped the mower over the wrong way getting oil into the air filter.

Build-Up Of Carbon Deposits On The Cylinder Walls

Another potential cause of black smoke is a build-up of carbon deposits on the cylinder walls or piston rings. When these deposits start to burn, they can produce smoke.

Faulty Valves

Faulty valves can also cause an engine to smoke. If the intake or exhaust valves are not sealing properly, it can allow oil and gas to leak into the combustion chamber. This will cause the engine to smoke.

Worn Or Damaged Piston Rings

If the piston rings are worn or damaged, they can also cause the engine to smoke. The piston rings seal the combustion chamber and keep the oil and gas from leaking into it. If they are damaged, it can allow oil and gas to leak into the chamber and cause the engine to smoke.

Engine Is Running Too Hot

Finally, if the engine is running too hot, it can also cause smoke. In most cases, lawn mower smoke is not a cause for concern and will dissipate quickly. However, if the lawn mower smoking appears thick or black, it could be an indication of a more serious problem and should be checked by a qualified technician.

What To Do If Your Lawn Mower Engine Smokes?

If your lawn mower engine smokes, it’s important to take action right away.

One common cause of engine smoking is dirty oil. If the oil hasn’t been changed in a while, it can break down and start to gum up the engine.

Another possible cause is a leaking fuel line. A small fuel leak can quickly turn into a big problem, so it’s important to check the lines for any signs of leaks.

Finally, a dirty air filter can also cause engine smoking. A clogged air filter won’t allow enough air to flow into the engine, causing it to run lean and producing smoke. If your lawn mower engine starts smoking, be sure to take action right away to avoid serious damage.

How To Fix The Problems And Stop The Smoke In Lawn Mower Engine?

There are a few simple steps you can take to fix the problem and stop the smoke.

Fixing The Problem

  • To start, make sure you’re using the correct fuel and oil. If you’re not sure what kind you should be using, consult your owner’s manual.
  • Make sure the oil is not over flowing. Use the dip stick to check the oil level is correct.
  • Once you’ve got that, clean or replace your spark plugs. Dirty spark plugs can prevent the engine from starting properly, which can cause smoke to build up.
  • Finally, check your valves for any leaks. If there is an intake valve leak, it will allow too much oil to enter the combustion chamber, causing smoke. If there is an exhaust valve leak, it will allow hot gases to escape before they have a chance to cool down, again causing smoke. By taking these simple steps, you can fix most problems that cause engine smoke.

Lawn Mower Maintenance Tips To Prevent Engine Smoking

If the engine isn’t properly maintained, it can start to smoke, which can be both annoying and dangerous. Here are a few tips to help prevent your lawn mower engine from smoking:

Check The Oil Level Regularly

Check the oil level regularly and add more if necessary. Never over fill.

Clean The Air Filter Regularly

Clean the air filter regularly and replace it if it becomes clogged.

Replace The Spark Plugs

Replace the spark plugs every few months.

Inspect The Muffler & Exhaust System Regularly

Inspect the muffler and exhaust system regularly for any blockages or damage.

By following these simple tips, you can help ensure that your lawn mower runs smoothly and doesn’t smoke.

Additional Resources For More Help With Lawn Mowers

If you’re still having trouble with your lawn mower, there are a few additional resources that can help.

  • First, check the manufacturer’s website for troubleshooting tips and instructions. Most companies have extensive FAQ sections that can provide helpful information.
  • You can also find helpful videos, diagrams, and photos that can show you how to fix the problem.
  • Finally, if all else fails, you can always take your lawn mower to a qualified repair shop. With their expertise and experience, they should be able to diagnose and fix the problem quickly.

By following these steps, you can be sure to get your lawn mower back up and running in no time.

Further Reading

  1. To minimize maintenance be sure to buy the best lawnmower in the first place. Our list includes the 3 best gas and 4 best electric mowers.
  2. After stopping the smoking of your lawn mower you may want to change the oil with the correct type of lawn mower oil.
  3. If you don’t want to deal with oil or smoke then check out the best electric mowers. They have no fumes or maintenance.

About your guide: Jamey Kramar is a certified Lawn Care Manager (NALP) and a Mechanical Engineer by trade. He has been writing about outdoor power equipment for 11 years and has been quoted in NYTimes, Popular Mechanics, HowStuffWorks, iFixit, Realtor.com, and more. He spends his spare time disassembling things and also building an off-grid cabin at his 200-acre property.