What Parts May Cause Abnormal Engine Noise?

In daily car use, abnormal engine noise is a common problem for many car owners. When the vehicle starts or makes unusual noises during driving, it not only affects the driving experience, but also may indicate that there are hidden dangers of wear, looseness or even failure of internal engine parts. So, what parts may cause abnormal engine noise? Knowing this information will help us to troubleshoot the problem in time and avoid more serious mechanical damage.

1. Valve mechanism

The valve system (including valves, valve tappets, valve rocker arms, etc.) is an important part of the engine, responsible for controlling intake and exhaust. If the valve clearance is too large or the valve seat and valve do not match well, it often causes a "da da da" metal knocking sound. Especially when the cold car is started, the abnormal noise is more obvious. In addition, valve spring fatigue may also cause abnormal vibration and sound.

2. Crankshaft connecting rod system

The crankshaft and connecting rod system bear the most intense motion load in the engine. When the connecting rod bearing or main bearing is severely worn, the engine will have a dull "dong dong" sound when accelerating or idling. This sound is mostly periodic and accompanied by changes in engine speed. If it continues to be used, it will lead to serious consequences such as connecting rod breakage and engine locking.

3. Piston and cylinder liner

The piston moves up and down in the cylinder at high speed, and the cooperation with the cylinder wall is crucial. When the piston ring is severely worn, or the gap between the piston skirt and the cylinder liner is too large, a metal impact sound similar to "knocking the cylinder" will be generated. This sound is usually more obvious when the engine is cold, and it will be alleviated after the engine temperature rises, but it should not be ignored.

4. Timing chain or timing belt

The engine timing system is related to the precise cooperation between the valve and the piston. If the timing chain is loose, the tensioner is damaged, or the sprocket is worn, it often causes a continuous noise of "swooshing" or "clicking". In contrast, the problem of the timing belt is usually manifested as a sharp whistling sound, especially at the moment of starting or during rapid acceleration.

5. Generator, water pump and pulley

The accessories at the front end of the engine, such as the generator, water pump and air conditioning compressor, can also cause abnormal noise. Once the bearings of these components are aged or poorly lubricated, a sharp "squeaking" sound will be emitted. In addition, poly-V belt slippage, loose pulleys or eccentricity may also be the source of abnormal noise.

6. Ignition system and fuel injection system

Although the ignition system itself does not directly produce noise, if the ignition timing is wrong or the fuel injector works abnormally, it may cause incomplete engine combustion, resulting in "knock" or "knocking" noise. This type of abnormal noise often occurs concurrently with reduced engine power and increased fuel consumption.

7. Engine mounts (engine brackets)

If the engine bracket (commonly known as engine mounts) is aged or damaged, the vibration of the engine during operation will be directly transmitted to the body, causing resonance abnormal noise, especially when starting or shifting gears.

Summary

The abnormal noise of the engine is not a trivial matter. In many cases, it is a precursor to the aging or failure of certain parts. If there is a persistent abnormal noise of unknown origin, you should go to a professional repair shop for diagnosis as soon as possible. Through regular maintenance, replacement of worn parts, and maintaining good driving habits, you can effectively extend the life of the engine and avoid small problems from developing into major failures.