Lawn mower smoking in a yard.

Lawn Mower Smoking And Leaking Oil From Exhaust? Causes And Fixes

5 minutes

Half the battle with lawn mower maintenance is just knowing what’s happening and why. So, if your lawn mower is smoking and leaking oil from the exhaust, knowing what’s going on and why can give you a big boost in getting your lawn mower back on track quickly. Before going over that though, we need to take a quick detour so we can talk about safety.

What Should I Do If My Lawn Mower Is Smoking Or Leaking Oil?

Closeup of a person working on their lawn mower.
It never hurts to call a professional.

The bottom line is that if your lawn mower is behaving differently, smoking, leaking oil, it’s a good idea to give yourself some distance from the machine, especially if it’s smoking. Shut it off, if you can, and back away to a safe distance. Give it some time and see what happens because being safe comes before anything else.

If you’re sure that it’s safe to begin figuring out the issue (or getting a professional’s help), we recommend going about it carefully. Although we’ve tried to be as thorough as we can below, there could be other reasons why a lawn mower is smoking or leaking oil.

That said, let’s get to the ones we do cover.

Possible Reasons For Oil Leaking Or Smoke Coming From Lawn Mower Exhaust

There are a few reasons why oil or smoke might be leaking from a lawn mower exhaust. The first possible reason is the lawn mower might be tipped the wrong way.

Lawn Mower Tipped The Wrong Way

You might wonder why anyone would ever tip their lawn mower the wrong way. There are a couple of reasons, such as maintenance, storage, or an accident. Whatever the reason, it can happen, and it can lead to oil leaking out of the exhaust.

This would happen if it manages to leak from the oil tank into the exhaust. When oil leaks like this, it can also end up burning while the engine is running, which can lead to smoke that’s colored blue, black, or white.

The best thing to do here is to make sure the oil doesn’t have a way to escape from the oil tank. This may mean tightening the oil tank cap, performing maintenance with the lawn mower sitting upright, storing the lawn mower in a better way, and so on, but it’s better than oil leaking out of the exhaust.

Faulty Carburetor

A faulty carburetor is also a reason for the oil leak. The main function of a carburetor is to mix air and fuel so that proper combustion can take place.

If the carburetor fails to properly mix the fuel and air, then some fuel will be left not burnt. This could lead to the engine not working properly, which can push oil out of the exhaust and also smoking. If you notice issues, it might be time to replace your carburetor.

Blocked Air Filter

Air filters help keep out all the things you don’t want in your lawn mower. Sometimes they can become blocked with so much dirt and debris that they actually prevent air from getting into the engine. Lawn mowers need both gas and air to work, so if this happens the engine might start having issues, which might force oil out the exhaust and can also cause it to burn, which causes it to smoke.

The easiest way to fix this is to stop it from happening at all. Check your air filter according to the owner’s manual’s recommendations and replace or clean it as needed.

Overfilling The Oil Tank

Some people think that you need to fill an oil tank all the way to the top. This isn’t a good idea. When pouring new oil into the oil tank, use the dipstick to check the oil level. There are 2 lines on a dipstick, and if the oil level is showing between these 2 lines, then the oil tank has enough oil.

Pouring too much oil into the oil tank can make it overflow into other parts of your lawn mower. This may not seem like a problem at first, but it can become a problem later. Also, a higher oil level means a higher chance of oil leakage and burning if the lawn mower is tipped the wrong way.

Parts Malfunctioning

Sometimes the air filter and carburetor are just fine. Sometimes, parts just malfunction either because of poor manufacturing or wear and tear from using the lawn mower. When these things happen, it can lead to oil leaking or to the lawn mower smoking.

Conclusion: Lawn Mower Smoking And Leaking Oil From Exhaust

It’s never a good thing when a lawn mower is behaving in a way it shouldn’t. This is true whether it’s not cutting the grass properly or if it’s making weird noises. This is also true if the lawn mower is smoking and leaking oil from the exhaust.

By now though you should have a pretty good idea of what to do if that situation happens. That said, we are curious about your other lawn mower adventures.

What’s the craziest thing your lawn mower has done while you were using it? We’d love to hear your stories in the comments below!

Todd L Miles
Lawn Mowers Enthusiast
I started "Landscape and Lawns Care" to provide clients with lawn care with better service, better products and, most importantly, better ethics. My promise to every customer is to give the greenest grass possible while controlling weeds, insects, and diseases! The most important thing is that I strive to always do the right thing for you, your lawn and your wallet!