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Why Is My Lawnmower Smoking

Why Is My Lawnmower Smoking
Last Updated: 27 December 2019

Have you ever needed to do chores, mow the lawn when lo and behold, smoke started pouring out from your lawnmower? It may come across as something a bit scary, but usually, it won’t be so serious. There are numerous reasons why your lawn mower’s engine smokes, such as an oil chamber is too full, a leak or oil somewhere and many others, but we’re going to take you through everything you need to know. This article will look at how to stop a lawnmower from smoking and what to do with a lawnmower engine so that it can perform as needed. By the end of the reading, you should be equipped to handle any smoke-related problems. You will also know how to prevent smoke from emerging in the future. Let’s take a look at different problems, what they mean and how they can be avoided.

What Does White Smoke Mean? Possible Reasons

What Does White Smoke Mean?

It can often be a very disturbing sight when you see a cloud of white smoke emerging from a lawnmower. So what does white smoke mean? White vapor coming out is a sign that the lawnmower’s engine is, in fact, burning oil, however, oil has probably got there for some innocuous reason. One could have spilled a bunch of oil on the housing or he/she may have overfilled a crancake. Perhaps oil entered a combustion chamber when it was turned over and cleaned – whatever happened, it’s might be just an accident. Even something like mowing a lawn on a hill or gradient can cause some oil to spill and enter into the mower’s combustion chamber.

What to Do


Now that you know about technical aspects, you might be wondering about how to stop white smoking. If you let your mower run then lawnmower smoke is likely to stop. When using two-stroke mowers, it’s possible that you’ve added too much oil to gas. The correct proportion is usually around 40-1 and 50-1. If there is any excess oil, it won’t actually hurt an engine, however, if you want all smoke to stop then you should change the fuel.

Often when you’re using a brand new mower for the first time, it’s possible to see some white vapor coming out of it. Rest assured that it is probably a result of any oil residue that has been left by the manufacturer and there is probably no need to send it back or get it repaired. The best thing to do is simply let your lawnmower run. As you do this, the engine will burn away residue and all-white smoke should cease soon.

What Does Black Smoke Mean? Possible Reasons

What Does Black Smoke Mean?

Lawnmower engines can often puff away black smoke when the mix of air and fuel becomes too dense. When there isn’t enough air, fuel can’t combust properly, thus, all unburnt fuel that is left in a combustion chamber starts turning black and emits vapor. If one has ever burnt a pile of leaves outside, they can see how tight packing stops air from circulating leading to black vapor.

If you’re wondering “why is my lawnmower smoking?”, it’s probably a sign that the ratio between gas and air is much too rich. It’s likely that the device is consuming a lot more gas than it should be doing when it’s operating. Black vapor could also indicate that oil in the mower has migrated into their cylinder thus the lawnmower is trying to burn both this and the fuel. Sometimes after black gas, it will be difficult or even impossible to restart your lawnmower.

What to Do

Dirty filters are usually common causes of black vapor puffing out and are relatively easy to fix yourself. It’s as simple as removing a lawnmower filter and then cleaning it with soapy water. The majority of filters are made up of either paper or foam. If yours is made of foam then it might need an additional coat of engine oil before it can be reinstalled. Paper filters can’t be cleaned as easily and so it’s recommended replacing them entirely. The problem that a dirty air filter causes the inability of the lawnmower to pull in the right amount of air. This results in the mix of air and fuel that is too dense.


If vapor still persists after this, you should adjust fuel mix, making it leaner by turning a carburetor screw of a lawnmower. Any mower’s manual will come with instructions on where this can be located and how to twist this screw. Lawnmowers typically have 2 screws to adjust that are mounted around the outside of the unit – one is to adjust the air and others to adjust the fuel mix.

It is within the carburetor bowl that a float rises and falls depending on the amount of gas. If you can see that float sticks or have developed a hole, you might not regulate how much gas goes into the carburetor. As a result, the mix is too rich and a smoking engine won’t be able to start. We recommend that if you do encounter black smoke as a result of your carburetor, take it to a qualified mechanic for correct servicing because it can be a bit of a fiddly operation.

The last thing to check is a choke. When one starts a lawnmower, choke closes allowing the carburetor to send a gasoline mix to a cylinder. Once an engine has started, choke opens in a way that dense mix isn’t necessary to keep the engine running. If choke does stick, the gas mix becomes much too rich. Check any of the linkages to choke, making sure that they work correctly and that they are free from any dirt or debris. Make sure to have the best lawnmower batteries that provide enough power to run the lawnmower smoothly.

What Does Blue Smoke Mean? Possible Reasons

What Does Blue Smoke Mean?

If your lawnmower smokes blue color, it isn’t an indication of anything going terribly wrong. Don’t be alarmed, a genie isn’t going to appear out of the lawnmower either! This color of smoke indicates a problem much like that of white vapor whereby oil has seeped into an area where it shouldn’t have been.

If too much oil was poured into your lawnmower, or if some of it spilled onto some other part of the engine as it was filled up, blue vapor may appear once the engine is hot and the lawnmower is running.

What to Do

If you’re wondering how to stop your lawnmower from smoking blue then you could use the tips we’ve provided when the lawnmower smokes white. As an addition, you can try and keep your spark plug tilter upwards so that it doesn’t leak as easily. This is especially good if you want to mow on a hill – mowing on hills and gradients could cause additional oil spilling.


Wrap Up

It can be disconcerting when your lawnmower blowing white smoke or when you notice your lawnmower starts then stops to emit a smelly cloud, but hopefully, with tips we’ve provided, you’ll be able to solve any vapor related problems. Most smoking comes from spilled oil on engine parts so do make sure there isn’t any oil leaking from lawn mower areas and avoid putting too much oil in a lawnmower. Now that you’ve read this article, you should be well equipped to avoid gas problems and know how to stop a lawnmower from smoking. Have a great time out in the sun mowing. Best of luck!

Had any recent troubles with your lawnmower? Folks at homemakerguide.com would love to hear more about your problems – send us comments below.

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