What Causes a Loud Noise When the Engine is Cold?

[LeElliot]

Engine cold start noise can be caused by a cracked exhaust pipe, worn spark plugs, depleted oil level, or damaged engine bearings. Cracked Exhaust Pipe: If the engine noise is coming from the exhaust pipe, it is highly likely due to a crack in the exhaust pipe, which can be resolved by replacement. Worn Spark Plugs: A high-pitched noise during high-speed engine operation may be caused by worn spark plugs or clogging due to dirt, and can be fixed by replacement. Depleted Oil Level: If the engine noise is very low and deep, it may be due to depleted oil level, which can be resolved by timely refilling. Damaged Engine Bearings: If the engine noise changes with the maximum power RPM, it may be due to damaged engine bearings, which can be fixed by replacement.