Oil leaking into the spark plug wells is an indictor of a fairly serious problem that should be inspected and repaired immediately. It is almost always due to a failing gasket or O-ring but can also be the result of a failing piston or worn valve guides.
Leaky O-rings (spark plug tube seals) are probably the number one cause of oil on spark plugs. Spark plug tube seals keep engine oil, coolant, and everything else on one side of your spark plugs, so they remain dry. If these rings fail, engine oil can leak into your spark plug well and onto your spark plugs.
First of all, it's not normal. You'll never see oil on vehicle spark plugs or spark plugs in four-stroke engines, like those in lawn mowers and snow blowers. Oil only collects on spark plugs in two-stroke engines, like those in chain saws and leaf blowers. That's due to how oil lubricates different types of engines.
Oil fouling occurs when oil is allowed to enter the combustion chamber. Oil deposits cover the spark plug which can keep the spark from arcing across the gap. Instead it takes the shorter path to ground through the oil. Usually a sign of advanced engine wear.
The spark plug wire rubber boots may get soaked with oil, causing a misfire or rough idle.
Black, oily deposits on the electrodes and insulator tip points to an oil-fouled plug. Oil could be leaking into the cylinders, getting past pistons that are worn or valve guides that are worn. Finding the source of the leak is very important – consult a mechanic for guidance.
Specifically, if the PCV valve malfunctions, or is stuck open, it allows some of the oil that is used to lubricate the pistons and cylinders to escape. This wayward oil can then find its way to the surface of the engine's spark plugs, resulting in a condition known as “oil fouling.”
Cost Of Replacing A Valve Cover Gasket
On average, it'll cost you around $100 to $350 to replace the valve cover. You've to pay 30 to 50 bucks for parts and 70 to 300 dollars for labor fare.
A wet spark plug likely means that it hasn't been firing due to engine flooding or a bad ignition cable. Dirt or moisture on the outside of the spark plug that provides a conductive path to ground, or an internal crack in the spark plug's ceramic insulator that shorts the plug to ground also can be the culprit.
If the engine is running rough or your check engine light illuminates, the cause may be excess oil contacting the spark plugs and causing a misfire.
It is not recommended that you drive with a leaking valve cover gasket, as this can lead to overheating and engine insufficiency, as well as extensive engine damage.
Engine is running rough and misfiring
Sometimes when oil leaks from a valve cover gasket it leaks all the way down to the spark plug well and eventually seeps inside the spark plug tubes. This will cause a misfire or reduce engine performance. It can also cause a fire under your hood if it goes unrepaired.
Common signs of a faulty PCV valve include excessive oil consumption, oil leaking, a blocked breather filter, and reduction in overall performance.
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.
If you found oil has entered the spark plug tube galley then the oil may have shorted out all the coils and plug wires causing the engine no start.
NOTE: When an engine has been burning oil, the spark plug(s) will accumulate burned oil residue around the electrode area, which can harm the engine's performance. Clean or replace the spark plug(s) once the cause has been addressed and the engine stops producing white smoke.
Symptoms Of Engine Sludge
Engine sludge is another possible reason. This is because the thickening oil can impact the normal function of components inside your engine, impacting the oxygen sensor readings, causing misfires, and much more.
Shaking or vibration may be caused by many different things such as faulty spark plugs, poor fuel pressure or misfires. Other things such as a faulty idle air control valve may cause the engine idle to drop below the normal idling RPM which may also cause the motor to shake or vibrate more than normal.
FACT #4: YOU SHOULD CHANGE SPARK PLUGS EVERY 100K MILES OR SO. So, if good spark plugs are the key to avoiding these issues, how long do spark plugs last, exactly? The general rule of thumb about how often to change spark plugs is that they should be replaced after about 100,000 miles of driving.