Oil on spark plugs, also called oil fouling, is commonly caused by failing valve stem guides and bad stem seals. As pressure builds up in the crankcase, excessive oil enters the combustion chamber through worn-out piston rings or cylinder walls and forces its way to spark plugs. Oil fouling can also be caused by transmission fluid sucked through malfunctioning vacuum modulators or leaking lubricants from engine turbochargers.Know More
The most common sign of spark plug fouling is engine misfires, explains How Stuff Works. Oil blocks the electrical current needed to create sparks that combust fuel, leading to poor performance, higher fuel consumption and bad emissions. Misfiring engines shake badly during idling and can be felt throughout the vehicle. The excessive vibrations can cause engine mounting eventually to fail.
Extreme cases of oil fouling can cause hard starting, engine stalling and ignition coil failure. The ignition coil is connected to spark plugs by high-tension wires and sends surges of electricity to fire the plugs. Oil-fouled plugs send the surges back to the ignition coil instead of its normal path. These surge backups can push ignitions to failure.
According to AAA1Car.com, oil-fouled spark plugs are easily fixed by sanding the deposits and wiping them with a clean cloth, though replacing them is a better option.Learn more about Car Parts & Maintenance
Automotive supply shops such as AutoZone and O'Reilly Auto Parts carry spark plugs. Over time, as spark plugs develop wear and tear, it's necessary to change them to maintain optimal performance of the engine.Full Answer >
To clean spark plugs, disconnect the cables, remove the spark plugs, scrub them with sandpaper and a wire brush, wipe them with solvent, reinsert them, and reattach the cables. This 45-minute process requires work gloves, a bench vise, sandpaper, a brush, a ratchet wrench, solvent and rags.Full Answer >
To replace spark plugs, remove each spark plug wire by pulling the caps, and then unscrew each of the plugs and remove them. Next, use a plug-gapping tool to properly gap the new plugs. Finally, screw in the new plugs and attach the plug wires.Full Answer >
A gap gauge is used to ensure the proper gap size when installing new spark plugs in a vehicle; to find the proper gap size, refer to the vehicle's manual or the specification decal found under the hood. If the gap size is not set properly, the engine loses power and the vehicle loses fuel efficiency.Full Answer >