Oil in the Spark Plug Well: Symptoms, Causes and Fixes

The presence of oil in the spark plug well is one issue that raises concerns amongst car owners. It occurs because the spark plug o ring is faulty and can no longer keep the plug well sealed. Without swift action on fixing this issue, there may be some engine problems.

When it comes to the ignition of vehicles that run on gasoline, spark plugs are essential. Similarly, oil is crucial for the smooth running of the car’s moving parts, acting as a lubricant. In fact, an insufficient supply of oil can cause serious friction and engine overheating.

Nevertheless, there shouldn’t be any leakages that result in oil seeping through the plug well, as it can hinder the vehicle’s functionality. There are various causes of oil in the spark plug well, and you can look out for some common symptoms and quick fixes.

how to fix oil in spark plug well

Causes of Oil in Spark Plug

When your spark plug is in good condition, the car’s ignition should run optimally, and you shouldn’t face any hassles. But what happens when you find oil on the bottom of the spark plug? Well, this issue involves two distinct systems; the spark plug system and the lubrication system.

Both work well for the engine, as the spark plug ignites energy in the combustion chamber containing the fuel/air mixture. Whereas oil in the engine works well for the moving parts, reducing the friction between them.

Engines store the oil in the oil pan – it can hold six quarts of oil. The oil moves with the oil pump’s aid, traveling down to the oil filter before it reaches other parts.

However, the oil should not reach the spark plug well, as it can cause some severe issues. There are five major reasons why you find oil on spark plug wells, and they include:

Worn-Out Valve Cover Gasket: After a look at your car’s engine, you will notice a metal cover on the engine, known as the “valve cover.” This seal is designed to prevent possible leakages from the vehicle’s engine. Nevertheless, there lie gaskets between the valve cover and the engine, and with time they tend to fail.

Such failure becomes more pronounced with the engine’s high temperature, and as such, the valve cover gasket starts appearing brittle. Thus, you may soon notice some leakages, which may allow oil to enter the spark plug well.

Faulty O-Rings: If you’ve handled your spark plugs regularly, you will notice the O-ring seals beneath the spark plug tubes. These seals work effectively, acting as a cover for the spark plug well. Nevertheless, they start to wear out with time, and once damaged, oil can leak into the spark plug well.

Hence, the need for a swift action to prevent further issues. Kindly note that you would also change the current spark plug since the oil would saturate it and make it unsuitable.

Failed Piston Compression Rings: Above and beneath the piston are piston rings that prevent oil flow into the car’s combustion chambers. These rings also aid greatly in getting out the excess oil that reaches the cylinder walls.

With worn-out piston compression rings, they can rarely prevent oil from moving toward your spark plugs. In such a case, you would perceive the engine oil smell around the cabin. Also, you would notice blue exhaust from the car each day.

Bad Piston: Aside from a faulty piston ring allowing engine oil to flow to the cylinder and saturating the spark plug, a bad piston can also cause the oil in the spark plug well. Due to excessive heat, the piston may soon start cracking.

Such a faulty piston can result in engine misfire, excessive oil combustion, and rattling sounds while the car runs. You shouldn’t overlook such an issue and fix it quickly, as swift action would improve your engine’s performance.  

Aged Valve Guide Seals: The air intake into the car’s engine is one task that the valve guides help in taking care of, and they secure the valves within this operation. The valve guide seals are effective but may soon start appearing worn with frequent use.

You may need to get them replaced at some point, as such action would prevent oil from reaching the spark plug well. If you don’t, there may be some serious problems for you to handle, as oil shouldn’t get to the spark plugs.

Read Also: What Causes Oil on Spark Plug Threads 

Oil in Spark Plug Well Symptoms

A few symptoms tell you there’s oil in the car’s spark plug well. At the sight of these common signs, you will promptly discover such an issue and fix it before the car develops further problems. Recognizing these signs is crucial when to remove oil from the spark plug well. Some of the common symptoms of oil in spark plug wells include:

Oil in the Spark Plug Well

Gas Smell from the Tailpipe: Ever wondered why you keep perceiving the smell of gas from your car’s exhaust pipe? Well, this could mean that your Toyota Camry has oil in the spark plug well. This applies to various other vehicles, and in some cases, the smell penetrates the car cabinet.

Blue Smoke from the Exhaust: The exhaust pipe may soon start emitting blue smoke, signifying the combustion of oil somewhere in the engine. In most cases, such signs become visible when there is oil in the spark plug well.

Once there’s oil on the spark plug, they automatically affect the engine’s efficiency and how it burns fuel. There is an increase in fuel supply since the ECU tries to tweak the fuel ratio. Nevertheless, the excessive fuel in the combustion chamber would pass through the exhaust valve unburnt.

Decreased Engine Performance: Since the oil in the spark plugs well touches the plug, it causes a decrease in the generation of spark. Remember, this spark is responsible for the ignition that occurs in the car. The oil contamination of the spark plug’s tip would affect it adversely.

In essence, there would be lesser chances for the fuel/air mixture to ignite in the vehicle’s combustion chamber. Without proper combustion, there won’t be sufficient pressure that the engine needs to work effectively.

Engine Misfiring: Engine misfires can occur due to incomplete fuel/air mixture combustion in any of the engine cylinders. With oil on the spark plug, there are fewer chances of the plug generating a spark for the complete ignition of the gas/air mixture. Hence, you would start noticing your vehicle’s engine misfiring.

Increased Fuel Consumption: An increase in the car’s fuel consumption is a sign of oil messing with the spark plug. In essence, when you start noticing a high usage of fuel, then you should do well to check the spark plug to see if there’s oil on it. This sign can guide you on how to get oil out of the spark plug well.

Engine Backfiring: Often, engine backfiring occurs when the fuel/air mixture combusts outside the engine cylinder’s combustion chamber. You can notice this symptom when there is oil in the spark plug well. It results from the improper combustion of the fuel particles, causing them to forcibly move to the exhaust.

How to Fix Oil in Spark Plug Well

It is crucial to learn how to fix oil in spark plugs. Whether you find oil leaking from spark plug motorcycle engines or oil on your spark plug threads, you can follow these steps below to get them fixed.

Step One

Conducting Quick Checks: Act swiftly by first turning off the engine and getting the vehicle’s battery disconnected from the terminal. If you get the negative terminal detached, it should be enough to stop the supply of power.

Step Two

Remove the Valve Covers: For you to see the spark plug, you must try to take out the vehicle’s valve cover. You can do this by gently pulling out the bolts. It may appear pretty tight; hence, the need for a proper tool. Ensure that you don’t cause any damage to the cylinder head while you try to remove the bolts.

Step Three

Get the Spark Plugs Out: Using the suitable tool, remove all the spark plugs, and inspect the well for traces of oil. You should also try to inspect them for wear and tear and get the affected plugs replaced. If you have issues doing so, you can seek an expert’s assistance.

Step Four

Removing the O-Ring Seal: Using the right tools, start peeling off the existing gasket, and clean the cylinder head and the valve cover. You can use a suitable degreaser for this task to help prepare these surfaces for the installation of the new O-ring seal. Ensure the substances do not reach the internal area of the engine.

Step Five

Reinstalling a New O-Ring Seal: The spark plug o ring replacement is pretty easy. You can get it done in no time, and once you are done with this process, you should try to replace the spark plugs. It will help if you check for the best options available in the market.

Final Words

Spark plugs are essential for gasoline-operating vehicles, as they help in engine ignition. Thus, the spark plug must remain in good condition for the engine to run smoothly. Issues with the spark plug would affect the engine adversely, and you may even notice the car starts but won’t stay running.

With oil in the spark plugs well, there would be less spark generation for ignition. Thus, it may seem crucial to clean the spark plug hole and replace the spark plugs and O-ring seals. You can read through this piece to learn more about the causes, symptoms, and fixes for oil on the spark plug.

Learn More:

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

2 thoughts on “Oil in the Spark Plug Well: Symptoms, Causes and Fixes

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts