What Causes Engine Odor?
2 Answers
Engine odor is caused by burning engine oil. The following introduces specific reasons: Combustion chamber: Carbon deposits in the combustion chamber cause the piston rings' compression rings to stick, resulting in poor sealing. Lubrication system: Sludge forms in the lubrication system, which blocks the oil return holes of the oil control rings, weakening their oil-scraping performance. Between piston and cylinder wall: Wear occurs between the piston and cylinder wall. Valves: Corrosion and aging of valve seals lead to sealing performance failure. Others: Additionally, modern vehicles are equipped with a crankcase ventilation system (PCV valve). If this malfunctions, it can also accelerate oil consumption. Different vehicles may produce different odors. Automotive repair experts note that normal exhaust should be colorless and odorless, while exhaust with unusual colors or smells may indicate underlying vehicle faults.
That day while I was driving, I suddenly smelled a pungent odor, like burning plastic or grease. Based on my experience, it’s most likely engine oil burning off, because the internal seals have aged or there’s a cylinder issue, causing the oil to leak into high-temperature areas and burn. Sometimes it could also be coolant leakage, which emits a sweet smell, as antifreeze vaporizes when overheated. Additionally, short circuits in electrical wiring can produce a burning smell, which is particularly dangerous and may lead to a fire. My advice is to pull over immediately and inspect the engine bay if you notice such a smell, but avoid touching anything rashly to prevent electric shock. The best approach is to have a professional repair shop diagnose the issue, as it concerns safety—prolonged neglect could cause the engine to fail or even catch fire. For maintenance, regularly changing the oil and checking the wiring can effectively prevent such situations.
