What Causes Engine Noise in Cars?

[VanRafael]

Reasons for engine noise in cars: 1. If a rhythmic "ticking" sound comes from the upper part of the engine and its frequency increases with engine speed, this abnormal noise originates from the piston top hitting the cylinder head; 2. If "clanking" or "tapping" sounds are heard from the side of the engine block during operation, it indicates a cylinder knock fault; 3. Rough engine operation can, in extreme cases, cause connecting rod bending deformation. A bent connecting rod will deflect the direction of cylinder reciprocating motion, resulting in knocking sounds during piston movement reversal; 4. Excessive valve clearance can cause continuous "clicking" contact sounds around the cylinder head during cold engine operation. The frequency of this noise is directly proportional to engine speed but tends to diminish as the engine warms up.