If enough oil is in the combustion chamber, the deposits can build up on the tip, porcelain or shell. If you can't determine if it is carbon or oil fouling, smell the plug; it will smell like engine oil. The oil can come from the piston rings, valve stem seals or the positive crankcase ventilation (PCV) system.
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.
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.
you notice a foul smell from the exhaust.
any time there is incomplete combustion, raw fuel can enter the exhaust and cause a smell similar to sulfur or rotten eggs. this can indicate a problem with a spark plug not working properly.
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.
Your Spark Plugs are Loose
The spark plugs in your engine need to be tightened or else they can leak fumes into the car's combustion chamber. This component sits right next to your HVAC intake, which is why you may start to notice a gasoline smell. Remove each spark plug and closely inspect the coils.
Usually, overheated circuits can cause the plastic casing and other chemicals in wires to melt or burn, leading to a sharp smell around the home. The annoying part is pinpointing the scent to your electrical outlets because it may not be your first guess.
When a circuit overheats, the plastics and heat-resistant chemicals used in outlets, circuit breakers, or wiring insulation may emit a fishy or urine-like smell. The odor can be carried throughout the house by the HVAC system, and it may intensify or fade with changing temperatures and circuit usage.
Overflowing engine oil can also lead to bent engine rods and collapsed valve pipes. Spark plug fouling – Excess oil can find its way into spark plugs, which will then need to be replaced.
Ordinary copper and nickel spark plugs should be changed every 30,000 to 50,000 miles, unless otherwise suggested by the spark plug manufacturer. Platinum and iridium spark plugs tend to last longer than standard copper and nickel spark plugs. Expect to change them every 60,000 to 150,000 miles unless otherwise noted.
If your car has a burnt oil smell, this could indicate an oil leak or low oil level. Check the level with a dipstick and look for leaks around the area. If your oil level is low, schedule an oil change as soon as possible. If you suspect a leak, head straight to a mechanic.
One of the most common electrical faults announces itself with a strange fishy smell from a wall socket or switch. Generally, such a smell is caused by the arcing of electrical device.
This smell often comes from a gas known as hydrogen sulfide, which is formed when bacteria grows in sewage, drains or the ground. If you don't use the drain or sink often, the hydrogen sulfide could come directly from the sewer itself. When water in the p-trap dries up, the gas can rise from the drain.
Rough Idling
This will likely lead to a bumpy driving experience, and another common symptom of this type of misfire is the smell of fuel in the cabin.
In general, it's best to replace spark plugs as part of preventative maintenance based on manufacturer's specifications. This can help save you from costly repairs, as driving with misfiring spark plugs could put undue stress on your car's catalytic converter (the engine's exhaust cleaner).
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.
If the engine is running to lean, the spark plug can look greyish white. If the engine is running to rich the spark plug will look black, sometimes a glossy black if it's really rich.
Oil in Combustion Chamber
Especially a problem in older vehicles, take notice if your vehicle starts to burn oil, as it can be an indicator that your spark plugs may be damaged, and therefore have a shorter lifespan.