Smoke rolling out of your Ferris mower can be quite alarming. You may immediately think you have a significant costly repair coming up in the near future, but actually, it may not be that bad.

The first thing to do when you see smoke coming from the mower is to immediately stop operating it. Continuing to run a mower that is smoking can make the damage worse.

A Ferris lawn mower may begin smoking when the air filter is plugged; the engine oil level is low or too high; a gasket is bad causing an oil leak, or there is internal engine damage like a valve train or piston ring problem.

Before performing diagnostics and repairs, wait for the engine to cool and remove the spark plug wire. Follow all safety precautions provided in your Ferris operator’s manual.

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating.Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Reasons Your Ferris Zero Turn Lawn Mower is Smoking

Plugged Air Filter Will Cause a Ferris Lawn Mower to Smoke

Operating a zero-turn isn’t a clean task. Dirt and debris get tossed into the air. In very dusty, dry conditions with sparsely covered lawns, you be left in a cloud of dust.

These conditions can plug the air filter when not cleaned regularly or replaced. A plugged filter will restrict the amount of air your engine receives to continue to run.

First of all, never run your mower without an air filter, not even if it’s for a short while you wait for a new replacement air filter. Without a filter, dirt and debris can get to the engine through the air intake causing damage to the cylinder and engine seals.

Second, always run your mower with a clean air filter. I find it’s best to start each mowing season with a new air filter and clean it several times throughout the season.

It only takes a couple of minutes to check the filter before you run your mower. Taking time to do this can save you from costly damage to the engine.

When the air filter is extremely dirty, covered in oil, or damaged, you must replace it.

Why does a plugged air filter in your Ferris lawn mower cause it to smoke?

• The engine’s inability to get good air will cause your engine to run rich so black smoke will emit from your mower. This means the fuel and air mixture the engine requires to run has a higher concentration of fuel.
• Smoke can be a result of your air filter becoming so plugged, it restricts all air to the engine. The engine will begin drawing air from wherever it can find it including the engine crankcase. When it draws air from the crankcase, it can also pull oil from the crankcase that burns off in the cylinder.
• When your Ferris mower begins to smoke, the air filter can become plugged with smoke making your engine problem worse.

Follow these cleaning instructions for your type of air filter:

Clean an Ferris paper air filter element

• Remove the filter from the air filter housing.
• Wipe out any dirt remaining in the housing with a dry clean cloth. Do not allow dirt and other particles to fall into the air intake.
• Tap your filter against a solid surface to get as much dirt to become loose and fall out of the filter as possible.
• Hold your filter up to a light source. Reuse your filter if you can still see light shine through the paper. If you can’t, it’s time to buy a new filter and install it.
• Reinstall the air filter and attach the air filter cover.

Insufficient Engine Oil Will Cause a Ferris Mower to Smoke

The crankcase is designed by the engine manufacturer to hold a specific amount of engine oil. It’s important to fill the oil only to the “full line” as indicated on the dipstick.

Having too much engine oil or too little engine oil in your mower can result in a costly repair bill or even an engine replacement.

Engine Oil Level is Too Low in Your Ferris Mower

A low engine oil level won’t give your internal engine parts the lubrication they require to move freely. When there isn’t enough oil, friction begins to build which causes your engine to get hot.

It can become so hot that the oil begins to burn and engine parts begin to melt creating smoke. Once you find your engine is smoking because of low engine oil, you can attempt to add fresh oil and run your mower.

Chances are, if your mower became so hot it began smoking because of low oil, you have caused engine damage that can’t be easily solved by correcting the engine oil level. You are better off bringing your mower to an experienced small engine mechanic to be diagnosed.

Because of the damage that can be caused by running a low level of oil, it is important to take a few minutes before each mowing to check your mower over including checking the engine oil level. It’s best to catch this problem early and avoid running your mower in this condition.

Engine Oil Level is Too High in Your Ferris Mower

Most people know it’s not good to run the engine when there isn’t enough oil in it, but many people don’t know you shouldn’t run more oil than required in the crankcase.

Too much oil increases the pressure in the crankcase. This can push oil into the cylinder and even into the air intake through the valve train. The oil in the cylinder will begin to burn off and create smoke.

For additional problems, you can encounter from running your Ferris with too much oil, check out “This is What Happens with Too Much Oil in a Lawn Mower“.

When you find too much oil in your crankcase, correct the engine oil level by removing a little oil. You can do this by removing a little oil through the drain plug or oil filter.

You can also use an oil evacuator or turkey baster to suck a little oil out of the oil fill area.

After removing a little oil, recheck your engine oil level using the dipstick. Continue to add or remove oil until the level is at the “full” level.

Check the air filter to make sure it is not covered in oil or has become plugged from smoke. If it is, install a new air filter.

Bad Gasket Will Cause a Ferris Lawn Mower to Smoke

Smoke coming from your Ferris mower could be the result of a bad gasket on your mower causing engine oil to leak. When oil is leaked onto a hot surface, like your muffler, it will begin to burn off and smoke.

Internal Engine Damage Will Cause a Ferris Lawn Mower to Smoke

The smoke coming from your Ferris mower may be the result of internal engine problems. Once you have reached the point where you are looking for an internal reason for smoking, it becomes increasingly difficult.

Identifying the exact cause of an internal engine problem will not be possible without tearing down the engine and performing leak-down and compression checks.

However, there is one simple check that will signify you have an internal engine problem, but it won’t tell you the exact problem.

To complete this check, remove your spark plug(s) and check for signs of oil on the plug. Oil on the spark plug will indicate you may have a piston ring or valve train problem.

You’ll need a small engine mechanic to diagnose your engine to find the root cause. While this check can’t tell you what kind of problem you have, you’ll know you have a problem that needs to be addressed by a mechanic.

A small engine mechanic will be able to diagnose the engine and find the root cause of the damage.

Piston Ring Problem in a Ferris Mower Engine

Your engine will need to be torn down to find a problem with your piston ring. When a piston ring or scoring inside the cylinder wall is found, oil can enter the combustion chamber and burn off causing your Ferris to start smoking.

Valve Train Problem in a Ferris Mower Engine

A Ferris mower that has overheated can develop a burnt valve. The only way to determine a burn valve problem is by removing the cylinder head and performing a leak-down test.

This test and repair should be performed by a small engine mechanic. The mechanic will have to cut the seat and the valve correctly to properly complete the combustion chamber.

Your Ferris Lawn Mower is Blowing Blue, White or Black Smoke: What’s the Difference?

I always recommend going through the steps above to identify the cause of the smoke coming from your mower. However, identifying the color of the smoke can point you in the direction of the potential cause of the smoke.

Blue or White Smoke coming from your Ferris mower is associated with the burning of excess oil. This could be from oil burning off in the combustion chamber from damaged piston rings, valve train, or engine gasket leak. It can also be the cause of oil being pushed into the cylinder from a plugged air filter.

Black Smoke coming from your Ferris mower is associated with excess fuel burning. This is due to a plugged air filter allowing the ratio of fuel and air to have a higher fuel concentration.

When the Ferris mower runs rich, it can emit black smoke. If the air filter is not the cause, look for another air restriction in your mower.