Oil in the cylinder is an issue that can happen due to numerous reasons like a leakage in the valve cover gasket, faulty compression rings, damaged gasket, worn-out valves, etc.

Oil in Cylinder Issues With the Mower

If you need to know which of these reasons can be a source of oil leakage, our experts are here to resolve your queries.

Read on as we inspect these causes in-depth and help you resolve them once and for all.

What Are The Reasons For Having Oil in Cylinder? 

The reasons for having oil in cylinder is a leaking valve cover gasket, failed piston compression rings, or blown head gasket. Moreover, it would also be due to worn valve guide seals, defective O-ring seal, or having some damaged piston rings.

Why are my spark plugs wet with oil? Several causes suggest the presence of oil in cylinder head.  But it is equally important to know the symptoms before looking at the reasons. Oil in cylinder symptoms includes increased fuel consumption, poor engine performance, inevitable engine misfire, and increased gas smell, which means that these would be different issues that you would face. However, it is possible to clean your mower’s spark plugs.

– A Leaking Valve Cover Gasket

A valve cover gasket sits atop of the cylinder and is one of the most exposed to high temperatures. It is responsible for keeping the oil to one side of the cylinder, preventing it from entering the rest of the engine. 

There eventually comes a time when these gaskets fail, but this is one of the reasons why it is permitting oil to get into the cylinder. This failure is more noticeable when the engine’s temperature rises and the cover gasket becomes fragile. It causes leaks that allow the oil into the spark plug well, hence the machine would be in different complications.

– Failed Piston Compression Rings

These rings are located at the top and bottom of the piston, and the rings are responsible to prevent oil from entering the combustion chambers, but in case they are damaged, the issue would arise. They are also responsible for removing the extra oil from the walls of the cylinder. 

Reasons For Having Oil in Cylinder

The worn-out rings cannot stop the oil from moving toward the spark plugs. In such a case, the engine oil odor is easy to notice and this would mean that the compressions rings have been damaged. You can also see blue smoke emitting from the engine occasionally, and the problem is clear now.

– Blown Head Gasket

A head gasket rests between the piston head and the engine block. It plays an important role in sealing the combustion chamber and stops the oil from contaminating and depositing on the spark plugs. These spark plugs play a huge role in maintaining the health of your engine.

The gasket also stops the coolant and the motor oil from mixing as they move through the lubrication system to the cylinder’s head. Motor oil can easily contaminate the combustion chamber if you have a damaged gasket, on another note, it can also leak into your spark plugs and spark plug threads.

– Worn Valve Guide Seals

A valve cover is a small metal cover on the engine. The seal helps to keep the leaks far away from the engine. Gaskets between the engine and the valve cover are present, but they ultimately fail, and this would start to jumble the oil compartment

The failure is more noticeable with the rise of the temperature’s engine, and the valve gasket becomes even more fragile. The valve becomes weak when there is an impurity in the metal. As a result, the valve springs lose their strength and cause the valves to open, providing a passageway for the oil to enter the spark plug hole.

– Defective O-ring Seal

If you have ever had the chance to work with spark plugs, you know about the O-ring seals under the spark plug tubes. They are round and cross-sectioned, resembling an O shape. Due to their durability, these seals are made of rubber and widely used in machines, and they would protect the mower well, but, in case they would start to wear off, the damage is great. 

These work as seals that cover the spark plug well. Unfortunately, these seals weaken over time and, when damaged, can be a source of the oil entering into the spark plug well.

– Damaged Piston Rings

The rings are effective gatekeepers that stop oil from entering the combustion chamber. But, a faulty piston, or broken piston rings, cannot live up to the expectations and allow oil to penetrate one or more cylinders.

How To Stop Oil Leaking?

To stop oil leaking in cylinders, you should let the mower rest for a bit, burn the oil off, or try to wipe the oil. You may also try to grab your kitchen baster, tilt the mower to stabilize the machine, lastly, you can also try to seek professional help. 

The reasons sound quite overwhelming, but they can be solved with common solutions. These solutions can be time-consuming, so you need all the patience you can come up with. Furthermore, these remedies have the best effect when you have observed the symptoms closely. 

– Let Your Mower Rest

As strange as it sounds, allowing it to rest can do wonders, basically you will let gravity be the one doing the job, as it allows the oil to slide back into the crankcase, where it belongs slowly.

Stop Oil Leaking in Mower

Only move on to the rest of the solutions once you have given plenty of rest time to your mower, but make sure that you wouldn’t tilt it more than the necessary angle. But if still the results are unsatisfactory, you can try more solutions or methods.

– Burn the Oil Off

Sometimes, you must get the mower running, allow it to breathe outside, and burn the oil off. However, you can use this remedy in only two scenarios. The first is after you have allowed the mower to sit and rest for a few hours, or a day, to drain the excess oil out. 

The second condition that restricts the use of this solution is if there is very little oil in your cylinder. There is less fuel in the cylinder either when you have added oil according to the oil marks on the engine or there is a small amount left. Burning the oil does not have immediate effects on the mower.

However, you would want to avoid having the mower running consistently, this could be a way to do it, yet again, you should be really careful on how you would manage this task with all cautiousness.

– Wipe the Oil

A good way to wipe the oil is by accessing the cylinder through the spark plug well. Since we do not have a lot of room to work with, the solution rests in using a paper towel and a thin marker. Simply wrap the paper towel around the marker and insert it in the cylinder. 

Give the wrapped marker a good turn, reaching the walls of the cylinder, making sure you get to every part, leaving no hidden oil behind, and simply let the wipe absorb the leakage well. You should also push the marker around the cylinder’s wall several times until you have removed most of the oil. This solution applies to both two-stroke and four-stroke engines.

– Grab Your Kitchen Baster

This solution might sound weird, but it can be very effective. A kitchen baster works well to push the oil out of the cylinder, and as you squeeze it, it will fill the oil in, where you will dump it, and try to collect them all. This solution has the same steps as wiping the oil from the cylinder; however, an extra effort can go a long way. 

Attach a plastic tubing at the end of the thin marker to get to the oil sitting at the pit of the cylinder. After this step, if you have managed to soak up most of the oil, run the mower for some time to burn the leftover oil.

– Tilt the Mower

You can tip the mower over with somebody’s help to get the clingy oil out. Ensure that you are tilting the mower correctly, as many mowers come with instructions regarding the sides to which they can be tilted, which means be mindful of this choice. The spark plug must be facing down, as that is where the oil will drain, hold the mower so that when tilted, it doesn’t slip and fall. 

Allow the mower to remain tilted so that no oil is left behind. In addition, you must also make sure that the air filter is facing upwards, or you can even remove the air filter before tilting the mower for better results. Removing the air filter is extremely important, or you will end up replacing it because it will be soaking in oil after you tilt the mower.

– Seek Professional Help

If you have tried each of the mentioned remedies and nothing works for you, seek professional help immediately. Observe the symptoms closely and if they prolong, take it to your nearest mechanic, or have someone come and visit and let him find the root cause of the oil leakage, especially if it needs the key parts to be removed, replaced, or readjusted. 

Once the professional has found the primary cause, he can guide you accordingly. Listen closely to all his instructions and keep a close eye on the symptoms, so you can deal with them quickly and avoid any major inconveniences.

Remove the Air Filter Before Tilting the Mower


Understanding why there is oil in the cylinder is easy now that you have carefully read our article, and you have even learned, or should we say, how to deal with and resolve the causes.

Let’s sum up the key points we mentioned so that you are fully prepared to help your mower:

  • Spark plugs are the first to be affected by the oil as they sit on the top of the cylinder heads.
  • Keeping a close eye on the symptoms can help you in the long run, for example, by saving your fuel economy.
  • Pay attention to even the slightest bit of oil on the cylinder parts, especially the spark plugs.
  • Give your mower plenty of time to rest. The resting position can help the oil coming out of the cylinder back where it should be.
  • Seek professional help if you struggle with the remedies, as it can be another serious issue.

After reading our suggestions here, you can now prevent and control the oil from entering the cylinder and save your mower from getting damaged permanently.



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