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This is Why Your Exmark Mower is Smoking

I just saw my buddy and there was smoke rolling out of his Exmark. I asked him what was going on with it and he didn’t know. I walked over to the mower, pulled out the air filter only to find it completely plugged with dirt and grass. This is one of many reasons your Exmark may begin smoking.

An Exmark mower may begin smoking when the air filter is plugged or there is an insufficient engine oil level where the level is too high or too low. An Exmark may have a piston ring problem, valve train problem or bad engine gasket causing the mower to smoke.

Your Exmark mower may have a Kawasaki, Kohler, Briggs or Exmark engine. I’ll share with you steps to troubleshoot your engine’s smoking problem. I’ll explain when to attempt fixing your issue yourself and when to have your local engine mechanic work on your Exmark.

This is why your Exmark mower is smoking

Exmark Lawn Mower Air Filter is Plugged

An air filter is the first line of defense to protect your Exmark’s engine. Its function is to filter air to prevent dirt from entering your engine’s air intake. While your Exmark can run without an air filter, you should never do this as you are allowing debris to enter your engine.

Debris in the engine will shorten the lifespan of your engine and cause extensive engine damage. The amount of money you’ll save by not running an air filter is far less than the amount you will spend on an engine repair or engine replacement.

Your air filter must be kept clean so your engine has access to the air it requires. When your air filter becomes plugged, your engine cannot get a good supply of air. Your engine will emit a black smoke because it is running rich due to the lack of air being mixed with fuel.

Another problem you may have with a plugged air filter is when the filter becomes so plugged it can’t get any air. Your engine may begin looking for air wherever it can find it including drawing air and oil out of the crankcase and into the cylinder. Smoke is created when the oil burns off the cylinder.

Check your filter at least a couple times a season. It’s a pretty quick item to check and clean. Check it more often when you are using your Exmark in dry and dusty conditions or you are using your mower more often than the average homeowner.

Steps to clean your Exmark mower’s paper air filter:

  • Remove the air filter cover held on by thumbscrews or clips.
  • Remove the air filter from the housing being careful not to knock any loose dirt into the air intake. Wipe out any loose dirt from the housing with a dry clean rag.
  • Tap your paper filter against a solid surface to loosen and knock out as much dirt from your filter as you can remove. Never use compressed air to blow out your filter as this can damage the filter.
  • With your filter held up to a light source, look for beams of light shining through your paper element. Replace your air filter with a new filter when you don’t see any light shine through the filter. If you do see light, go ahead and reuse your paper filter.

Insufficient Engine Oil Level in Your Exmark Lawn Mower

Check the level of your Exmark’s engine oil by using the oil dipstick. The oil level needs to be at the full level as indicated on your dipstick. It should not be lower than this level or higher than this level as this can result in engine problems and cause your Exmark to smoke.

Exmark Has a Low Engine Oil Level

When your engine oil is lower than the required oil level, your engine will not have the oil it needs to lubricate the engine’s moving parts. The lack of lubrication causes increased friction among the moving parts of your engine. This increase in friction creates a heat that gets hot enough to begin melting your parts and burning off oil which creates a smoke.

You can try to add engine oil and run the engine to see if it continues to run, but most of the time this won’t work. Once an engine gets hot enough to smoke due to a lack of oil, it’s often too late for the simple fix of adding oil.

Bring your mower to your local Exmark dealership or small engine repair shop for the engine damage to be assessed. If you choose not to go to your Exmark dealer, look for a certified engine dealer for the engine in your Exmark: Kawasaki, Kohler or Briggs.

Exmark Has a High Engine Oil Level

Too much oil in your Exmark mower can cause increased pressure in your crankcase. This pressure will push oil into your cylinder and even up to your air intake through the valve train. Smoke is created from oil in the cylinder being burned off. Learn more about the effects of too much oil in this article.

When you find you have too much oil in your Exmark’s engine, you must remove some oil to bring it to the correct level. There are several different ways to remove oil from your Exmark:

  • Remove the drain plug and quickly replace it to only to remove a little oil. Have your drain pan ready to catch the oil.
  • Remove your oil filter and take oil from the filter. Replace your filter.
  • Use a turkey baster (yes, like the one from your kitchen) to suction oil from the oil fill area. Do not reuse the baster for cooking purposes. You’ll want to replace your kitchen tool with a new one.
  • Use an oil evacuator to vacuum out a little oil

Once you have removed some oil, check your oil level and top off, to the full level, if needed.

Piston Ring Problem in Your Exmark Lawn Mower

It’s time to identify if the cause of your Exmark smoking is due to an internal engine problem if your air filter and oil level is not the problem. There is an easy way to identify an internal problem, but it won’t actually indicate exactly what type of internal problem you have. In order to find the root cause, you will need a small engine mechanic to tear down your engine and perform tests.

Using either a 3/4” or 5/8” socket, depending on the engine in your Exmark, remove the spark plug to see if it has signs of oil which can indicate an internal engine problem. Finding oil on the spark plug may be a sign you have a piston ring or valve train problem. A small engine mechanic may find scoring in the cylinder wall that allows oil to enter the combustion chamber and burn off.

Valve Train Problem in Your Exmark Lawn Mower

Another internal problem you can develop in your valve train is a burnt valve. This is when the valve gets burned by being overheated. An additional sign pointing to a burnt valve or timing problem is when your muffler gets red hot.

The only way you can identify a problem in your valve train is by removing the cylinder head on your Exmark’s engine to perform a leak down test. It’s best to have this test performed by an experienced small engine mechanic.

If a burnt valve is found, the mechanic will have to cut the valve and the seat it at the correct angles. You must seat the valve correctly so it can complete the combustion chamber.

Bad Engine Gasket in Your Exmark Lawn Mower

An Exmark engine that has a bad gasket can leak oil. Depending on the location of your leak, oil can drip onto your hot muffler causing your Exmark to smoke when the oil is burned off. Your gasket may not be too difficult to replace, but it can be increasingly difficult depending on the location of the gasket.

Difference Between Blue and Black Smoke in Your Exmark Lawn Mower’s Engine

I recommend going through the list above to identify your smoking problem. However, the color of smoke can give you a clue as to what area on your mower you need to focus on.

  • Black Smoke – This color usually is due to your Exmark’s engine running very rich. This is when there is more fuel being burned than air so the first thing to check is the air filter and clean or replace. If this isn’t the issue check for another air flow restriction.
  • Blue or White Smoke – This color smoke is due to burning excess oil. It is best to follow the steps above to identify the root cause starting with checking the engine oil level followed by checking for damage of the piston rings, valve train or engine gasket.

You invested a considerable amount of money in your Exmark lawn mower. Checking your engine oil level and air filter before each mowing could prevent costly repairs.

Still Having Problems with Your Exmark Lawn Mower?

I’ve put together a handy guide for the most common problems an Exmark owner will encounter. When you own a mower long enough, you are going to run into many different issues with your lawn mower. Check out and bookmark this page to use as a reference when you need help with your Exmark.

Common Exmark Lawn Mower Problems & Solutions