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Why White Smoke Comes From Lawn Mower

You have just started your lawn mower, and there is a big cloud of white smoke coming from it. You get scared wondering what the issue is and whether it is safe to operate the lawn mower. 

There are various reasons that lawn mowers turn out to emit white smoke, and some of the causes are obvious. Most likely, you are seeing lawn mower white smoke as a result of oil spillage.

However, you might overlook some things that could be causing this problem. This is why we have decided to write this simple post, so you do not get confused and buy a new mower when your current one is not completely broken.

Lawn mower white smoking

Reasons Why White Smoke Comes From Lawn Mower

White smoke is not normal when you are trying to mow your lawn. There are so many reasons why white smoke comes out of the exhaust coming from a lawnmower. 

You need to know first that white smoke is actually white vapors of water being released by your engine. This will only happen if you are using the wrong oil grade for your mower, the oil in your crankcase is not enough, or if you have an air leak in the crankcase. 

So, what else do you need to look for? Your lawn mower’s engine needs clean fuel to run smoothly and efficiently. If it is filled with dirty fuel, then when you burn it at high temperatures inside the combustion chamber, unburned carbon will end up as black smoke instead. 

In order for your engine to operate at its best condition, there should be no air leaks within the crankcase in which the oil is held and lubricated. One of the most common causes of white smoke coming out of your mower’s exhaust pipe is due to the wrong oil grade being used. 

Most engine manufacturers require a special oil grade made just for their engines. Look for your owner’s manual and follow its instructions closely when it comes down to selecting an oil grade and filling up your crankcase.

Ways of solving the smoking problem of a lawn mower

Before heading to the solutions, let’s talk about the things that you can fix to solve the problems.

A blown head gasket could be the result of things such as a cracked manifold, burned valves and pushrod guides, or improperly torqued head bolts. Before replacing the gasket, you will want to rule out these other possible causes.

Filling the engine with too much oil is also a common cause of blown head gaskets. If you notice your mower leaking from the back end, chances are it has overfilled itself with oil. To avoid this, check the oil level frequently when you’re mowing and keep an eye on the dipstick.

The last cause of blown head gaskets is tipping the mower while you’re mowing. This can happen if you’re mowing uneven ground or if you’ve accidentally bumped into something while pushing forward. When tipped, the engine will fill with coolant that can damage the head gasket.

A damaged piston ring can cause a leaky head gasket in an engine as well. You won’t be able to see or feel a problem until you have to replace it, so be sure to check your owner’s manual for proper maintenance procedures such as changing the oil and cleaning out debris from the air filter.

Fix the Head Gasket

You have to replace the head gasket, but the process is not that simple. You need to be careful or you will ruin the engine.

You must replace the head gasket and you need to do it carefully because if you don’t seal properly, you will get another leakage and this time you might destroy your engine completely.

A blown head gasket is an issue commonly found in older lawn mowers because of its age. The leaking can damage parts of your engine and cause a lot of stress on other parts.

Head Gasket Lawn Mower
Head Gasket Lawn Mower

Replacing a blown head gasket doesn’t always work and if it does, it might cause more damage than good. If your vehicle has a blown head gasket, then you should look into repairing it before replacing it with a new one.

You need to seal the leak first, then you can try to run it again. If it still doesn’t work, you should replace your entire head gasket. It is very hard to fix. It would be difficult for an inexperienced person to do alone. 

You must replace the gasket because it is broken and cannot be repaired any more. But the good news is, it is not so expensive. You can easily find a replacement near you.

Don’t Overfill Engine

A lawn mower is a great way to take care of your yard. However, when you are using the mower and it emits smoke, you may be tempted to stop using it immediately and think that the machine is on fire. 

The smoke might be coming from the engine’s muffler. This is a normal occurrence and not a sign that the mower is damaged or malfunctioning. By understanding why this happens, you can be sure to keep your mower in proper working condition.

The main components of an engine are its fuel system, ignition system, cooling system and exhaust system. These systems all work together in order for the engine to run smoothly. 

When the engine is running, oil circulates throughout all of these areas. The oil helps to cool the engine and also lubricates it so that it can run smoothly without friction between moving parts.

The engine must be lubricated with oil to ensure smooth movement. If there is no lubrication, then friction will occur and damaged parts may be generated. Emission of smoke is one of these parts. 

It usually means that there is too much oil in the engine. So when you change your oil, do not overfill it! 

Overfilling engine oil is a common mistake. The simple fixes to this problem are:

  1. To understand how much oil or what type of oil you need, you need to read the engine manual.
  2. Don’t forget to check oil level regularly and overfill it when you put oil in your lawn mower.
  3. The engine oil shouldn’t be dirty otherwise it gets clogged in the fine screen at the bottom of the dipstick tube, so it cannot be read accurately.
  4. Always check the dipstick level to make sure you have put the proper level of oil.

Don’t tip the mower too much

Tipping the mower in the side may result in oil entering the cylinder where it may start burning, which will cause smoke to emit out of the muffler. To prevent this from happening, always try to mow on a level surface and only tip your mower up for storage purposes.

tip a lawn mower
Don’t tip a lawn mower too much

When you need to replace the blades or look under the deck, don’t tip the mower too much in the side as it may cause oil to enter the cylinder where it will start burning, which will cause white smoke to emit out of the muffler. 

You can also protect yourself by keeping an eye on your user manual as they usually have a knowledge on how to tip over your mower without causing any damage. 

Do not tip more than 15-degrees slope as it may cause oil to enter the cylinder where it will start burning and thus cause smoke to emit out of the muffler. To prevent this problem, make sure that your oil level is correct and free of dirt.


Smoke pouring from the engine of your lawn mower is a classic sign that something is wrong. But if you don’t know what’s causing it, that smoke can be a lot more than just a nuisance.

In this article we’ve discussed the reasons and the possible fixes. Hope, these will help you. If you can’t solve by yourself, then ask for professional help.

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