Oil plays an important role in the ensuring the seamless functioning of your vehicle’s engine. From cooling the vehicle down to lubricating its metal parts, oil lubricates the engine and absorbs heat, allowing the internal parts to work together effectively without overheating. Over time, the engine oil breaks down and wears out. But as important as oil might be, there are certain places where it is not meant to be such as the spark plugs.
If you notice oil on your vehicle’s spark plugs, we recommend you tend to the issue before it leads to other more serious or even catastrophic engine problems.
Spark plugs are part of a vehicle’s combustion system. The combustion chamber is sealed and only a mixture of air and fuel should be in contact with the spark plugs.

What Causes Oil to Reach Spark Plugs?

Leaking O-ring Seals

O-ring seals are at the bottom of the spark plug’s fitting, and one of their principle functions is to get oil far from it. In case an O-ring seal is harmed, worn out or just not working properly, it can allow some oil to spill through the valves, which ends up on the spark plugs and the engine misfires. If not fixed can prompt costly motor issues. Motorists need to check these seals often to avoid all of this

Leaking Valve Guides

Valve guides regulate the air intake into the combustion chamber by ensuring the valves are always in the right place when the engine is running. If the valve guides wear out or start leaking, spark plugs become more prone to ending up with oil on them due to the leakage. Spark plugs will be typically located between the in-take and exhaust valves in most modern vehicles.

Broken Piston

A piston is in the combustion engine for converting the fuel into energy to drive the car forward. You can tell when if your vehicle has a broken piston by looking out for things like engine misfire, significant power loss and a rattling noise as the car is running. As the piston heats up during its normal operation, sometimes the heat can become too much and cause cracks on it. If you leave this untreated, you may be paving the way for permanent vehicle damage of sorts.

Damaged Piston Compression Rings

Piston Compression Rings are at the top and bottom of the engine and in the cylinder walls for preventing the engine oil from leaking into the combustion chamber. If compression rings fail or get damaged, there will be nothing stopping the oil from sipping through the pistons and into the combustion chamber, where some of it eventually ends up on the spark plugs.

Valve Cover Gasket Leakage

A valve cover gasket is a component that is often installed on the cylinder head, meant to confine the engine oil inside it. Given the high operating temperatures in the engine, the valve cover gasket can wear out and get damaged over time. This means it will not be able to keep oil out of other engine components, and so some of it can end up leaking to your spark plugs.

Identifying Oil on Spark Plug

Engine Misfiring

Engine backfire will typically happen when there is no combustion in the cylinder, which can be a result of different things such as spark plugs failing to ignite. But, because different things can cause spark plug failure, you should combine this symptom with others on our list to be certain that oil is what is causing the spark plugs to malfunction.

Decrease in the Overall Performance of Engine

You can expect to get a decreased overall performance of your vehicle’s engine when one or more of its parts have become dysfunctional. So, when the spark plugs are not working, the engine tends to misbehave and its performance takes a hit regardless of the driving conditions.

Reduce Fuel Economy

Faulty spark plugs will also result in your vehicle using up more fuel than usual, and hence the fuel economy of your vehicle reduces significantly. This happens as the vehicle is not able to burn the fuel efficiently.

Blue Smoke Coming from Exhaust Pipes

When oil leaks to the tip of the spark plug due to any of the reasons mentioned above, it will get burnt along with the air and fuel mixture, and produce blue smoke on your exhaust

Gas Smell from Exhaust Pipes

If you encounter a mixture of gas and oil leaking from the tailpipe of your vehicle, accompanied by a peculiar gas smell that can also sometimes be felt inside the vehicle’s cabinet, then this also means that you most likely have oil on your car’s spark plugs

Engine Backfiring

Backfiring occurs when fuel particles are not combusted effectively. Oil in the spark plugs then enters the exhaust system with high energy, which is manifested in the form of small explosions.

How to Fix Spark Plugs having Oil

Correcting the situation is a fairly easy process for beginners as well as motorists. Here, we have highlighted the main points in simple steps:

Switch off the engine

Switch off the ignition and then disconnect the battery terminals to cut off any power supply on the vehicle.

Remove the Valve Covers

Open Valve Covers using a screwdriver and remove the tubes and spark plugs. Doing this exposes all the gaskets and seals that might be damaged and hence require some repairs or replacement.

Clean Head and Valve Cover

Use plastic tools for the cleanup to ensure you do not damage the valve cover or cylinder head. Also, make sure to use the appropriate greaser. Cleaning helps to eliminate traces of the old ones to ensure the news ones form a tight seal.

Install new O-ring Seal and Gaskit

Now install a new O-ring seal and Gasket. Remember to apply the right silicone if the engine type requires it

Install New Spark Plugs

The final step is to changeover the old spark plugs with new ones, to ensure there isn’t any more oil left in the chamber. Please note that the spark plugs might have already got damaged, therefore cleaning them and re-installing them might not be very effective.
Keeping these points to watch out for in mind, it should be easy to diagnose and fix the problem in good time before it causes more serious engine problems.

Call Now To Get Back On Road

Best mobile car mechanic service in Melbourne

  • +03 8001 8028

Sign up to our Newsletter

    (We do not share your data with anybody, and only use it for its intended purpose)