In advanced cases, the oil-saturated plug can cause a complete loss of spark, leaving the vehicle unable to start. The valve cover gasket acts as a barrier, preventing the thick lubricant above the cylinder head from dripping down onto the spark plug wires and cores.
Head Gasket Leak Causing Oil on Spark Plugs
Cracks in the cylinder head, a failing head gasket, or damaged piston rings allow combustion gases to enter the cooling system or crankcase. Unlike external leaks, internal leaks cause the oil to be atomized and burned off during operation, leaving behind a distinctive, fluffy, tan or gray carbon deposit on the electrode and porcelain of the spark plug.
How Spark Plugs End Up Saturated with Oil The presence of oil on a spark plug is never a random occurrence; it is the result of a specific internal leak. A more severe internal issue involves failed piston rings or a blown head gasket, which forces pressurized combustion gases past the pistons and into the crankcase, forcing oil up and into the combustion chamber where it coats the plugs.
Head Gasket Leak Causing Oil on Spark Plugs
When this rubber or silicone gasket degrades, it allows oil to seep down the exterior of the spark plug tube and onto the plug itself. This unwanted migration of pressure forces oil past the piston rings and up into the combustion chamber, a condition known as oil burning.
More About Spark plugs in oil
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More perspective on Spark plugs in oil can make the topic easier to follow by connecting earlier points with a few simple takeaways.
