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Lawn Mower Oil Smells Like Gas – What To Do?

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Mowing the lawn can be a tedious task, but it gets even worse when you start worrying about the smell of gas coming from your machine. Fortunately, this isn't the first time we've heard about this problem, and in this post, we've researched the cause of your lawn mower oil smelling like gas and ways how you can stop it.

If your lawn mower oil starts smelling like gas, it is highly likely that your carburetor is dirty; gas will seep past and overflow the carburetor. This will then cause the gasoline to end up in the oil cylinder. The oil of the lawn mower will now start to smell like gasoline, and you will have to clean out your carburetor and change the oil completely. 

We know that figuring out why the lawn mower smells like gas can be a little tricky. This is why in this post, we're sharing with you ways how you can prevent this from happening. Keep reading as we also share with you other reasons why your lawn mower starts smelling like gas and other troubleshooting tips to help you fix them.

Gardener doing lanscaping in the backyad with mower, Lawn Mower Oil Smells Like Gas - What To Do?

Why Does My Lawn Mower Oil Smell Like Gas?

Lawn mowers are important, especially if you are looking to keep your lawns and yards looking well-kept all the time. However, along with the work the lawn mowers have to do, it is also important to check on them from time to time. Every once in a while, you might experience different smells coming from your machine and it might worry you.

The smell of gas coming from the oil of your lawn mower isn't uncommon. In fact, this issue tends to happen a lot for many homeowners because of certain issues that cause the gas to mix with the oil. There are quite a number of reasons why this tends to happen, but mostly it is caused by a dirty carburetor. 

A dirty carburetor will often have issues with its needle and seat. Oftentimes, it becomes leaky, and the gas seeps past the needle, and it overflows the carburetor. During this time, the gas ends up in the oil cylinder, and it goes past the piston rings, which then end up in the crankcase.

The deposits that have built up on the carburetor needle and seat are one of the reasons why it doesn't seal properly. Gasoline also moves throughout the machine, and it pushes on the needle, so without a good seal, it allows the fuel to go past it. 

Lawn mower in a sunny garden at spring time operated by a gardener

What Do I Do If The Lawn Mower Oil Smells Like Gas?

Pensioner mowing lawn with machine

When your lawn mower oil starts smelling like gas, there are two important things that you must do to resolve the issue. First, it is important to clean the carburetor. Second, the oil of the lawn mower should be changed to get the smell out.

Dirty carburetors are often the leading cause of many issues with your lawn mower. You will have to disassemble it and clean it completely so that the fuel will not overflow. Ues a carb cleaner to minimize the carbon buildup in your carburetor, and it will keep it working seamlessly.

Get this carb cleaner on Amazon.

Aside from cleaning your carburetor, the oil of the lawn mower's engine should be changed. Warm the lawn mower's engine briefly before removing the oil and replacing it. Synthetic oil works best with many lawn mower machines. It is best to check your manufacturer's manual to see if there are specific preferences on the engine oil your lawn mower needs to use. 

Are There Other Reasons Why My Lawn Mower Smells Like Gas?

Man repairing an old lawn mower, gas engine

Other than a dirty carburetor and a need to change the engine oil, there are other reasons why your lawn mower is starting to smell like gas. Keep in mind that gas smells also leak from cracked valves and gaskets, and here are some of the places you might want to check on your lawn mower.

If you feel like you've checked all of these areas and your lawn mower still smells like gas, do not hesitate to call in a professional and have everything checked out. There might be some underlying issues that you couldn't see, and it will be a lot safer to fix these issues right away. 

Fuel Cap Gaskets

Gas caps are normally vented, so it's pretty normal to smell trace amounts of gas when you're working around the machine. However, if you've left your lawn mower inside the garage and the smell of gas is pretty strong, then there might be an issue there. Check your lawn mower's gas cap and the gasket inside, and see if there are any cracks. 

If the gasket of your cap is dry and brittle, you might want to consider replacing it. It should not be wrinkled, torn, or look like it has shrunk.

Leaky Fuel Lines

Check the fuel lines for leaks and residue buildup. Over time, the clamps might have some residue that has built up, and it might be causing the fuel to leak because of the weak flow. If this is the case, you might need to change your clamps and fuel lines to allow the gas to move better.

Check the fuel filter housing

Sometimes, the fuel filter housing of the lawn mower might have cracked without you noticing it. If it's leaking, make sure that the fuel pump isn't cracked and that the fuel filter is replaced with a new one. 

Residue Buildup on Carburetor

Check the bottom of your carburetor (or the carburetor bowl), and if you find residue has built up on it, this is a sign that you need to replace the gasket. The lawn mower's manual should be able to tell you what o-ring gasket you should get that will work best with your lawn mower.

Cracked Fuel Tank

If your lawn mower's fuel tank has received impact more than once, it is highly likely that it has cracked and that fuel might be seeping out. Check your fuel tank if it has damage and leaks, and make sure to replace it if you see any issues. It will also cost you less on having to replace gas more often than you should.

Using Bad Fuel

Some people have the tendency to store their gas in the garage and use it on their machines. However, gas has a shelf life of about 30 days before it goes bad. Gasoline tends to have a stronger smell as it is stored longer, so this might be the smell that you are experiencing.

If you are planning to keep your gas in the garage for more than 30 days, make sure to add a fuel stabilizer additive before keeping them. These stabilizers allow your fuel to stay fresh for a longer time, and this works well if you are going to keep gas in the garage for winter or just as an emergency backup.

Get this fuel stabilizer on Amazon.

Can Gas Make My Lawn Mower Smoke?

Repairing lawn mower and doing some maintenance

If your lawn mower suddenly spews out smoke, it is best to immediately turn it off and allow the machine to cool down. Check for issues afterward, and here are some of the things that might be causing the smoke.

Your lawn mower should be using the correct gas to keep it working. Lawn mowers use unleaded gasoline with at least an 87 octane rating, and ethanol content of 10% or less. You will most likely find this gas in your regular gas station.

Using the wrong gas for your lawn mower can cause the engine to run hot, thus making it smoke. Most lawn mowers will use unleaded gas, but always make sure to check your manufacturer's manual to see what the best gas is needed for your machine.

A smoking lawn mower can also be a sign that your filters are clogged or that your engine oil has run low. Make sure to check on these issues as well, because it might pose a dangerous problem in the long run.

Final Thoughts

Gardener doing lanscaping in the backyad with mower

Keeping your lawn mowers well maintained is the best way to prevent your oil from smelling like gas. Make sure to always have the carburetors checked, and you should change the oil when necessary. The machines will work better and longer if you keep them in their best shape, and it will definitely lessen any other costs you might incur if you need to fix them.

Are you looking for more information about your lawn mowers? We've got the perfect articles just for you:

How Fast Do Lawnmower Blades Spin?

Where To Get Gas For Your Lawn Mower [And How To Fill Its Tank]