Why is the engine noise louder after maintenance?
2 Answers
After maintenance, the engine noise becomes louder due to reasons such as incomplete draining of old engine oil, using a different type of oil than before, or overfilling with new oil. An engine is a machine that converts other forms of energy into mechanical energy. It originated in the UK and can refer to either the power generation device or the entire machine including the power unit. Engine types include internal combustion engines, external combustion engines, electric motors, etc. Taking the external combustion engine as an example, it burns fuel outside the engine. Invented by Scottish R. Stirling, it's also called the Stirling engine. This engine converts the heat energy from combustion into kinetic energy. The steam engine improved by Watt is a typical example of an external combustion engine.
After driving for so many years, it's quite common for the engine to sound noisier after maintenance. Last time I changed the oil myself and used synthetic oil with too low viscosity, which caused the engine to hum as if it wasn't lubricated properly. Upon inspection, I found the oil level was also too low—the new oil wasn't filled enough, leading to the noise. If the air filter isn't sealed tightly or the new filter is misaligned, the intake noise can become louder. Loose spark plugs can also cause disturbances—it's best not to delay and check the dipstick promptly to see if the oil level and viscosity match. If not, go back to the shop for adjustments; delaying might harm engine lifespan and fuel consumption. Also, consider whether belts or other components were adjusted during maintenance, as improper adjustments can cause resonance noise. In short, always ask the mechanic for details before doing anything yourself.
