What Causes the Metal Friction Sound When Starting the Engine?
3 Answers
Engine starting with a metal friction sound is generally a sign of damaged bearings in the generator, water pump, or power steering pump. Introduction to the engine: An engine (Engine) is a machine capable of converting other forms of energy into mechanical energy. The first external combustion engine was invented in 1816 by R. Stirling in the UK (Scotland) and later improved by Watt into the steam engine. Types of engines: The term engine can refer to both the power-generating device and the entire machine including the power unit (e.g., gasoline engine, aircraft engine). Types include internal combustion engines (such as gasoline engines), external combustion engines (such as Stirling engines, steam engines), gas turbines (used in racing cars), electric motors, etc.
Last time my car made this screeching noise when starting, the mechanic told me the most common cause is a starter motor issue. If the starter's pinion gear or flywheel ring gear is worn, they'll grind against each other during startup, producing a metallic sound. Another possibility is an aging, hardened engine belt with insufficient tension, which can slip and squeal during cold starts. In my case, replacing the belt immediately solved the noise. Insufficient oil lubrication due to a faulty oil pump or overdue oil changes can also cause dry friction between engine components. The most alarming scenario is a stretched timing chain rubbing against guides - this requires immediate attention to prevent engine damage. When hearing unusual noises, first check the oil dipstick, then have a professional inspect specific components.
One morning when I started my car, I heard a harsh metal scraping sound, which turned out to be a starter motor failure. If the starter's drive gear gets stuck or fails to retract properly, it will collide and rub against the flywheel ring gear during startup. Belt issues are also quite common—when the alternator belt or AC belt ages and cracks, its surface becomes smooth and starts to slip, causing a squealing noise. My neighbor’s car had a faulty water pump bearing, producing a buzzing friction noise upon startup. If the noise is particularly noticeable when the engine is cold, it might indicate low oil in the hydraulic lifters or a loose timing chain. In such cases, don’t panic immediately. Pay attention to how long the noise lasts—a brief sound may just be a starter issue, while a persistent one requires checking the engine’s internal lubrication.
