5 Causes of Oil Leaking Into Spark Plug Wells

Spark plugs are very important components of a vehicle because they are responsible for generating the spark which ignites the fuel and air mixture in the internal combustion chamber.

Oil is also important for lubricating the components of the engine while it is running. If you do not have a good supply of oil, then your engine will overheat from all the friction created by moving components rubbing against each other.

However, you’ll never want to have oil leaking into the spark plugs. This will create a huge problem with the functionality of your engine and its performance. The cause of oil leaking into spark plug wells should be investigated right away. Below are the most common culprits responsible.

Top 5 Reasons Oil Leaks Into a Spark Plug Hole

You will know when oil is leaking into the spark plugs because the signs will be there. Aside from a weaker engine performance, you may see blue exhaust coming out of the tailpipe or more frequent engine misfires.

You’ll then be forced to add more oil to your engine regularly to keep it functioning. If you don’t, then your engine will overheat to the point where internal damage is done or even to the point of it causing a fire.

To figure out how to stop this from happening, you must understand the causes of oil leaking into the spark plugs. Here are five of the most common causes.

1) Worn Valve Cover Gasket

valve cover gasket leak

The engine has a metal part on top of it called a valve cover. A valve cover gasket sits between this cover and the top of the engine cylinder head. This keeps the engine sealed so that oil does not leak from it.

However, all the heat from the engine will wear down the valve cover gasket as time goes on. It will eventually start to crack and become hard or brittle, which then allows oil to leak through the gasket.

You can simply replace the leaking valve cover gasket if you catch the problem fast enough. Otherwise, your engine may suffer permanent damage due to insufficient oil.

2) Old Valve Guide Seals

bad valve guide seals

Vehicles depend on valve guides to assist in managing the intake of air into the engine. Basically, the valve guides secure the valves during the operation of the engine. The only problem is that valve guide seals eventually start to wear out as you continue using your vehicle.

At some point, you will likely need to replace them because bad valve guide seals will not be able to prevent oil from leaking into the spark plugs. Once that happens, you could have a lot of problems with your engine that will cost thousands of dollars to repair.

3) Bad O-Rings

spark plug well seals

Under the spark plug tubes, there are O-ring seals. Once an O-ring becomes worn out or damaged, oil will leak through and make its way to the spark plug tube. You’ll need to fix this problem quickly before the engine is affected too much.

And since the oil saturates the spark plugs, you’ll need to replace the spark plugs as well.

4) Bad Piston

damaged piston

A piston can crack if it gets exposed to too much heat. Then it will start to make knocking sounds and rattle quite a bit. More important, a bad piston will let oil leak into the spark plugs and that will create all kinds of problems.

Your engine will misfire frequently, and you’ll experience a weaker engine performance. These are all things that will ruin your engine if the piston is not replaced promptly.

5) Bad Piston Rings

bad piston ring symptoms

Piston rings exist on the top and bottom of the pistons of an internal combustion engine. The purpose of the compression rings is to stop oil from entering the combustion chamber and to remove extra oil that gets onto the cylinder walls.

However, if you have worn out piston rings, then they won’t be able to stop oil from flowing toward the spark plugs. You’ll also see blue exhaust and there may be a smell of engine oil that consumes the cabin.

2 thoughts on “5 Causes of Oil Leaking Into Spark Plug Wells”

  1. I found that everyone I have spoken to in person that has a Toyota Camry (most commonly being this 94 2.2 4 cylinder) {yes, even still. LOL} has had the same problem, as well as many others. Thus the most common we know of is from the oil fill cap being in line and right next to the spark plugs. So oil constantly get to the plugs.

    Even when covering the area, if the wind blows just right, it will seep down to the spark plugs. Now whether this is an older car issue or something more common for those kind I’m not sure? Can not find anything this specific online.

    Do not have anyone to speak to about this issue now. Everyone seems to address all the other problems and solutions which one starts to dismantle the motor. I’m not really sure if taking the valve cover gasket off is necessary? Exactly how should I clean it and what to do now?

    One time it was misfiring and my ‘previous’ mechanic (Great, honest, fair & rare. Unfortunaly battling C! Thus on no bother) pulled the wire up a little bit so it almost stopped. Said will run on 3 cylinders until could get new plug and wire. Not one to run car hard anyway. Still, week later it stoped. Pushed back in and twas fine.

    I try to sop up the oil as quick as possible if spills. It seems like times I have spilt more and nothing has happened. Yet a bit and it starts to misfire again. Only as it sit still at lights. More so on damp days.

    I have replaced a plug and it was fine. Another plug another time, and it was NOT fine. So then suggested that I should replace the wires that I had just got a month before. Spent $80 on that new set. Cannot figure if a way to just test them? So i can replace just one if needed?

    Trying to be thorough and analyze every angle. Really cannot afford to take this to some shop. Only ever get expensive solutions. Most times unneeded, as if i was just a dumb girl.

    I have been disabled, so more limited now. Most of my dads tools were stolen from me. Still doing best i can. No way can i replace everything every time. Desperately need the vehicle but I’m afraid of causing further damage.

    I only must drive it a couple miles a day and sit through those couple lights. But how long can I do that, if at all now? If anyone can help me i would greatly appreciate it. Any and all good advice is desperately needed. Thank you so very much. Take care all! Jennifer

    • Hello Jennifer, I’m not one too comment on these websites, but I hope I can help (if you still have the issue) the way you can test a bad coil is disconnecting the cable that it is connected too. If the coil is bad the engine will not change, it will run the same. The idle will not go up or down. If you do the same on a working coil the idle will drop and rise due too the engine trying to compensate for the loss of 1 cyilinder. Try changing the faulty coil too see if that fixes the issues. Now with the oil leak I am unable to tell due too I am not too familiar with Toyota Camrys, hope I helped, happy Hoildays, and happy new year!


Leave a Comment