What Causes Loud Engine Noise During Car Startup?

[MarcusLee]

Excessive engine noise during startup may be caused by too much engine oil, which increases the stirring resistance of the crankshaft connecting rod, leading to louder noise. When there is an excess of oil in the engine, it creates unnecessary resistance to the rotation of the crankshaft, resulting in louder noise during startup, affecting power output and increasing fuel consumption. Below are other possible reasons for loud startup noise: Exhaust Pipe Issues: Modifying the exhaust pipe is crucial for achieving a roaring engine sound, but conversely, a cracked exhaust pipe can also cause excessive engine noise. Damaged Engine Bearings: The noise from damaged bearings will vary with the engine's maximum power output. Engine Valve Problems: If the engine noise includes a metallic clanging sound, it may indicate issues with the engine valves, which require professional repair.