Why does the engine sound louder and make a humming noise compared to before?
3 Answers
This indicates that there is excessive carbon buildup in the engine, which needs to be cleaned promptly. Below is an introduction to carbon buildup: 1. Definition of carbon buildup: A coking-like substance produced by unsaturated olefins and gums in fuel under high-temperature conditions during engine operation. 2. Types of carbon buildup: Throttle valve carbon buildup, combustion chamber carbon buildup, intake pipe carbon buildup. Methods for cleaning carbon buildup are as follows: 1. Engine drip cleaning method: Introduce cleaning agent from a bottle into the engine through a tube to clean the carbon buildup. 2. Additive cleaning method: Add a cleaning additive to the fuel tank, requiring multiple operations to effectively clean the buildup. 3. Direct disassembly cleaning method: Remove the engine, clean it, and then reinstall it, which carries certain operational risks.
My car has recently experienced similar issues, and the humming noise could stem from several common causes. Worn-out engine mount bushings can cause resonance and abnormal noises, especially noticeable during cold starts; leaking exhaust system gaskets produce a low, buzzing sound at idle; worn tensioner pulleys or alternator bearings result in noise that increases with RPM; a clogged air filter restricting airflow can also lead to unusual sounds. Last time I checked, I found shattered ball bearings in the pulley bearing—replacing the part made it much quieter. I recommend inspecting these four areas first, as minor issues left unattended may damage the engine block. Regular maintenance is crucial.
The most common cause of increased engine noise is oil-related issues. Last time my car had a buzzing sound, an inspection revealed the incorrect oil viscosity—using 10W-40 oil in summer actually increased resistance. When oil levels are insufficient, the hydraulic lifter valve clearance increases, producing a noise like grinding with a sander. Additionally, a clogged oil pump filter screen can lead to insufficient lubrication, intensifying friction between piston rings and cylinder walls. Don't overlook the belt system either; abnormal noises from bearings in the alternator or air conditioning compressor can transmit to the engine bay. It's best to open the hood after the engine warms up and listen for the source of the noise. Changes in sound at idle and 2000 RPM can help pinpoint the fault—don't wait until parts seize up before repairing.
