What are the reasons for loud engine noise when the car is warm?

[DelLola]

Engine noise when the car is warm can be caused by high oil viscosity, loose belts, high coolant temperature, excessive carbon buildup, etc. High oil viscosity: When starting a cold engine, if the oil viscosity is too high, it increases the wear on the starter motor and battery, resulting in louder engine noise during warm-up. However, if the oil is too thin, it may fail to form a sufficient protective film under high temperatures, leading to insufficient lubrication and increased component wear. Loose belts: If the car's belts are loose, the engine will produce louder noise during startup. It is necessary to check whether the belts are loose. High coolant temperature: This prevents the engine from dissipating heat in time, resulting in louder noise during warm-up. In this case, check the coolant level and top it up if necessary. Excessive carbon buildup: Over time, engine oil becomes thinner, leading to increasing carbon deposits. During warm starts, this reduces the car's power and produces louder noise.