What Are the Causes of Excessive Engine Noise?

[DiRyder]

Engine noise can be attributed to several factors: 1. Combustion noise. In gasoline engines, abnormal combustion phenomena such as detonation and surface ignition can produce significant combustion noise. In diesel engines, the rapid rise in combustion chamber pressure causes vibrations in engine components, leading to noise. Generally, diesel engines are noisier than gasoline engines. 2. Mechanical noise generated during engine operation. This primarily includes piston slap noise and valve mechanical noise. If there is a gap between the piston and the cylinder liner during operation, and the gas pressure acting on the piston causes strong impacts against the cylinder wall, piston slap noise occurs. 3. Valve mechanical noise mainly stems from gear transmission noise, which results from the impact and friction between gear teeth during meshing. Additionally, torsional vibrations of the crankshaft can disrupt normal gear meshing, thereby generating noise.