What Causes the Smell of Burning Engine Oil from the Exhaust Pipe?
2 Answers
If there is a smell of burning engine oil from the exhaust pipe, it may indicate that the vehicle is experiencing mild oil burning. Exhaust Principle: The commonly referred to 'lower exhaust' is actually the crankcase breather, a ventilation device. During engine operation, some exhaust gases from the combustion chamber can leak into the crankcase. If these gases are not promptly expelled, they can cause an imbalance in crankcase pressure. Therefore, the crankcase must be equipped with a ventilation device, and the exhaust gases discharged from this device are referred to as the lower exhaust. Oil Burning Phenomenon: Engine oil has a distinct smell, and normal engine oil doesn't have much of an odor. The smell of engine oil often refers to the burnt, scorched odor emitted when the oil burns, which is easily recognizable. If the engine emits the smell of burning oil, it indicates that the oil is participating in combustion. The most typical fault is mild wear of the four supporting components, where the piston rings become stuck due to carbon deposits, leading to poor sealing.
I previously encountered a burning engine oil smell from the exhaust pipe while driving. This usually happens when the piston rings in the engine wear out, causing oil to leak into the combustion chamber and burn along with the fuel, resulting in that distinct burnt odor in the exhaust. Additionally, leaking valve guides or deteriorated oil seals could also be the culprits—issues more common in aging vehicles. When there's excessive engine oil, it can also be sucked into the combustion process, so it's crucial to regularly check the oil level and quality. If left unaddressed, not only will the car consume more fuel, but it can also lead to carbon buildup, and in severe cases, the engine may require an overhaul. I recommend paying close attention to the oil condition during routine maintenance. If you notice the smell, take the car to a repair shop for inspection as soon as possible—don’t wait until it breaks down on the road.
