Blown Head Gasket Motor oil can get into the combustion chamber if you have a blown head gasket and leak into your plug wells and onto your spark plug threads.
Faulty Head Gasket
It is possible for oil to enter the combustion chamber in areas other than the valve guides. The most common area of problem is the head gasket. This will cause oil on the firing end of the spark plug. If you're finding oil on your spark plugs, it could result from a faulty head gasket.
A compromised valve cover gasket allows oil to leach from beneath the valve cover of an engine itself. As a result, this oil often seems into the void or well which encompasses the body of an engine's spark plugs.
Spark plugs often suffer as the result of a blown head gasket. The problem usually stems from coolant escaping onto the plugs. This coolant will form deposits commonly referred to as fouling on the head of the spark plug. The spark plug may take on a dirty, blackened, or corroded appearance as a result.
Oil and coolant leaks are common issues on many vehicles. Just because you see a leak doesn't mean you have a blown head gasket. If you see the majority of the oil or coolant seeping out from the engine block though, it could be an indication that the head gasket is no longer maintaining a seal.
Can I Drive with Oil on My Spark Plugs? Spark plugs that are significantly oil-contaminated can result in an engine misfire. Because a misfire can cause additional damage to other parts of the vehicle, such as the catalytic converter, it's a good idea to address oily spark plugs right away.
If the gasket is blown, it's possible for coolant, oil, or gas to get into the cylinders. This could foul or flood the spark plugs.
If you discover a milky brownish-yellow substance that is similar to the thickness of a milkshake, you probably have a gasket leak. The milky substance is oil mixed with coolant that has seeped past the head gasket contaminating the engine oil.
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.”
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.
The spark plug wire rubber boots may get soaked with oil, causing a misfire or rough idle.
Continuing to drive on worn out or damaged spark plugs can ultimately cause engine damage, so don't put it off.
Wet Fouling, 4-Stroke
If a spark plug from a 4-stroke engine has a wet, black oily film over the entire end of the plug, it may be wet fouled. Causes include worn valve guides, worn oil rings, plugged breather or plugged breather valve in the tappet chamber.
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.
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.
It may cause detonation, fouling of spark plugs or damage to catalytic converters. More oil than to lubricate the cylinder walls and piston rings is a bad thing and a sure sign that the engine needs real maintenance, now. In (very) extreme cases, the cylinder might even go “hydraulic”, which will destroy the motor.
The first symptoms of a head gasket that is failing are usually a slow loss of coolant with no visible leaks, engine overheating and/or a Check Engine light with cylinder misfire codes.
Common signs of a faulty PCV valve include excessive oil consumption, oil leaking, a blocked breather filter, and reduction in overall performance.