Categories of Engine Abnormal Noises?
3 Answers
Here is an introduction to the categories of engine abnormal noises: 1. Abnormal noises caused by excessive clearance: Clearance is an important indicator of automobile assembly quality. When lubrication, temperature, load, and speed are constant, abnormal noises become more obvious as the clearance increases. Some moving parts of the engine may produce abnormal noises due to natural wear that exceeds the allowable clearance range, such as knocking sounds between pistons and cylinder walls, or impact sounds between connecting rod bearings and journals. 2. Abnormal noises caused by poor lubrication: Lubrication is a crucial condition for the normal operation of an engine. The lubrication system provides functions such as cooling, cleaning, sealing, and rust prevention. When clearance, temperature, load, and speed are constant, the thickness of the lubricating oil film is influenced by the pressure of the lubrication system and the quality of the lubricating oil. High-quality lubricating oil and appropriate pressure can produce a better lubricating oil film. The thicker the oil film, the smaller the mechanical impact, reducing the likelihood of abnormal noises. If the lubricating oil film is too thin, wear increases, leading to noticeable and clear abnormal noises. 3. Abnormal noises caused by loose fasteners: Vibration during engine operation can cause certain components to loosen, resulting in impact sounds. For example, loose flywheel bolts or loose connecting rod bolts can cause abnormal noises.
There are quite a few categories of engine abnormal noises, and I think they should be classified based on sound characteristics. First is the knocking sound, like metal hitting, often occurring during acceleration, usually caused by ignition system issues or poor fuel quality—check the spark plugs and fuel. Second is the valve tapping sound, a crisp ticking noise, clear at idle, indicating excessive valve clearance or insufficient lubrication, commonly seen with aged engine oil. Third is the piston ring wear sound, a low, dull hum that worsens with increasing RPM, signaling internal wear or compression problems. Fourth is the belt system noise, a sharp squealing sound, noticeable during startup, often due to belt looseness or aging. Fifth is the bearing sound, a rumbling friction or scraping sensation, pointing to wear in the water pump, alternator, or crankshaft bearings. These issues are all warning signs; delaying repairs may lead to bigger failures, so it's recommended to promptly locate the issue with a stethoscope or consult a professional mechanic. Each type of noise has an underlying cause, and addressing it starting with simple maintenance can prevent future problems.
Over my years of driving, I've encountered several common types of engine noises. The tapping sound after startup is often due to insufficient oil, causing inadequate valve lubrication and resulting in knocking; the popping sound during sudden acceleration is usually caused by detonation, exhaust system issues, or ignition problems; the squeaking noise when the engine is cold typically indicates a loose belt or a faulty tensioner. I've also experienced a low growling sound during operation, which turned out to be worn bearings upon inspection. These sound variations can help distinguish severity: high-frequency knocking requires urgent repair, while low-frequency noise might only need routine maintenance. The solution is simple—first, check the oil level and belt condition yourself. If the noise persists, record it and compare it with a technician. Don’t underestimate abnormal noises; they can help car owners save money and prevent engine failure. Regular maintenance checks at scheduled intervals can significantly reduce risks. Sharing these experiences in hopes of making everyone’s driving experience safer.
