How To Stop Lawn Mower From Smoking?

On a beautiful sunny day, you are on the lawn with your lawnmower to do some trimming. You are in a jolly mood. You start the mower and it is creating a smoke show out of nowhere.

This situation can freak someone out a little bit who never faced this problem and keeps wondering how to stop lawn mower from smoking.

Generally speaking, it is not a sign of a serious problem most of the time. Often this can happen for some simple reasons which can be fixed straight away.

How To Stop Lawn Mower From Smoking?

how to stop lawn mower from smoking

There are multiple reasons for this occurrence to happen like an excessive amount of oil in the oil chamber, damaged air filter or carburetor, a leak of oil, etc. All these problems are solvable by yourself without the help of any professionals.

In this guide, I will walk you through the full process of DIY fixing lawn mower smoking. You will be able to know things like why it happens, how to face it, and prevent it from happening in the near future.

Understanding The Smoking Lawn Mower Problem

Mainly your lawn mower can create three types of smoke according to their color. So, instead of asking why is my lawn mower smoking, look for the 3 smoke colors.

  • Black
  • White smoke from lawn mower
  • Blue

Different colored smoke emits due to different reasons. So, each color of smoke has its own solving manual.

The basic tip to prevent the smoke is to use the right type and right amount of oil for the engine. You can know the type and amount from the manual.

Be cautious not to spill any oil on your mower when pouring. By the way, you can check this mulching lawn mower buying guide if you’re planning to buy one.

Enough with the intro. Now, be ready to dive into the world of solutions for the smoking problem of your mower.

Let’s Start With Black

Black smoke definitely looks scarier than a white or blue one. But I can assure you it is not as dangerous as it looks. This black smoke situation can be caused due to various reasons like a faulty carburetor or a dirty air filter.

  • The Carburetor can be the problem

clean a carburetor on a lawnmower

If the carburetor of your lawnmower is not performing accurately then it can create black smoke blowing from the exhaust.

The main job of a carburetor is to bring the air and fuel together and then mix them up in the perfect ratio. This process is responsible for combustion. The amount of fuel needs to be precise to add it to the incoming air.

Not enough fuel might lead to engine damage when too much fuel can cause incomplete burning of fuel thus leads to creating black smoke from the exhaust.

  • How to Solve The Carburator Problem?

The solution to this problem will vary with the design of the carburetor. For the older version of the carburetor, they use the adjustment needle to control the fuel flow.

For this version, you can adjust the needle to make it slightly leaner to correct the fuel ratio. You can use the user manual to find out the correct position for it.

In the newer version engine, they use fixed jets to maintain the perfect fuel ratio. The jets allow precisely the exact amount of fuel needed for combustion and they are fixed.

You can’t adjust them. Instead, they offer a kit called a “High-altitude” kit.

Engine manufacturers normally set the carburetor to produce a perfect air-fuel mixture at sea level.

So, to use it at a higher altitude you need to use the high-altitude kit as the air density is much thin there.

The last thing you need to keep in mind is that a clean carburetor is a must. You always have to keep it clean by following the process recommended by the manufacturers in the manual, to get the best output from it.

  • Air Filters too

Besides carburetor, a damaged air filter can cause a significant amount of black smoke in the exhaust.

The main job of an air filter is to keep the dirt, grass, and other debris out of the air. It ensures that that dirt doesn’t enter the carburetor or the engine.

You already know the importance of a perfect ratio of fuel and air in the carburetor. Regular inspection of the air filter is necessary to make sure it doesn’t end up clogged.

A clogged air filter will supply less amount of air than needed for the engine and will create an imbalanced mixture of air and fuel. The extra amount of fuel will lead to black smoke in the exhaust.

  • How to Fix The Faulty Air Filter?

To avoid this situation, check your air filter on a monthly basis and replace them once every year from your lawnmower. This requirement might change for a dusty mowing condition like a weedy field.

Follow the instructions given on the user manual to remove and replace it. Make sure to use the recommended air filter by the manufacturer to avoid any unwanted incident.

White Smoke Cloud

A cloud of white smoke might look like a reason to worry but most of the time it’s totally harmless for the lawnmower. The reason behind the white smoke from the lawn mower is that your engine is burning oil or it’s just a bad lawnmower brand?

Now, where did that oil come from?

Well, it can be the result of spilling some oil on the housing in a time of servicing or it could be the result of excess fuel used in the crankcase.

One can even send oil into the combustion chamber while trying to turn over the mower for some cleaning purposes.

Whatever the reason is, almost every time it’s just an accident and accidents can happen anytime with anyone.

  • How to Solve It:

lawn mower loses power when cutting

Sometimes a brand new mower can also blow out white vapor the first time you use it. That is because there is probably some oil residue left by the manufacturer.

The smoke will soon vanish if you just let the mower run for some time. The oil residue will be burnt away by the engine thus causing the smoke to go away.

This is the trick for all other cases of white smoke too. Letting your lawnmower run for a few minutes then the smoke is likely to go away. But if it doesn’t, try to replace the fuel with a new one and then run it again.

Blue Smoke

Blue smoke can be caused by the same reasons of causing white smoke. Like, there are traces of oil in some parts of the machine where it wasn’t supposed to be. Or if you accidentally pour more oil in the engine than recommended.

Excess amounts of oil or spilled oil in some parts of the engine can cause this situation. After turning on the engine it will become hot gradually and will probably start to make blue smoke around the mower.

  • Now The Solution:

The general solution is the same as for the white smoke as the reason behind both of them is almost the same.

As an additional solution, you can prevent oil leak while mowing. Oil spilling is a common case when someone is mowing in high places from the ground like on hills. To avoid spilling fuel, you can keep the spark plug leaning upwards.

In Case of Excessive Amount Of Smoke

If there is an excess amount of white or blue smoke from the mower even after following the instructions above, then that could indicate something else.

This type of situation can happen when there is a pathway for the oil to reach the combustion chamber through some worn seals. If that is the case, the smoke won’t go away so easily. It can even cause the engine to become dead.

The reason behind this could be a crack in the breathing tube or even a blown head gasket. These problems need the attention of professional lawn mower repairs.

Another reason behind this smoke might be a faulty piston ring. The job of a piston ring is to form a seal between the piston and the cylinder wall. Typically, there are three pistons used in a lawnmower engine.

The topmost one is the compression ring which ensures that the gas heat from the combustion isn’t allowed through the piston and into the crankcase. Wiping the cylinder wall to remove any excess oil is also its job and it makes sure that the excess oil doesn’t end up in the combustion chamber.

The middle one is the wiper ring which wipes excess oil and sends them to the crankcase to keep them away from the combustion chamber.

The last one is the oil ring with the job of controlling the application of oil to the cylinder wall.

If any of them wears down then the extra oil will reach the combustion chamber and will produce an excess amount of white smoke by burning.

The piston rings can wear due to a faulty air or fuel filter as it will allow dust and dirt to enter the combustion chamber and also to the piston rings.

Some Extra Advice

You don’t have to keep asking yourself how to stop lawn mower from smoking if you follow my guide. Always read the user manual given with the lawnmower thoroughly and try to follow the instructions. The user manual points out all the necessary things to do to keep the mower running perfectly.

Plus, if there is a problem with your mower and you decide to solve it by yourself using the solutions from the internet. Then try to fix one suggested part at a time and check if that solves it.

By doing it you will know which part was causing the problem and you will know what to do if it happens again in the future.

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