What Causes the High-Pitched Metal Scraping Sound When Accelerating?

[StMiranda]

When accelerating, the high-pitched metal scraping sound is due to abnormal brake pads. Here is a detailed explanation of this phenomenon: 1. Principle: The abnormal noise when brake pads are thin is intentionally designed. A small metal piece is installed on the brake pad. When the brake pad thickness is normal, this small metal piece maintains a certain distance from the brake disc, preventing contact. When the brake pad wears to its limit, the small metal piece comes into contact with the brake disc, causing a squeaking sound due to metal-to-metal friction, alerting the driver to replace the brake pads immediately. 2. Solution: If the noise occurs, promptly inspect the brake pads. Many vehicles may stop making noise after a while because the small metal piece has been worn away. However, continued use may wear out the brake pads completely and even damage the brake disc. Always check the thickness if the brakes make noise. After the brake pad warning, there is approximately 2 millimeters of thickness left, allowing for a few hundred kilometers of driving without issues.

[SanSabrina]

I also encountered a situation where there was a metal friction sound when pressing the accelerator last time I drove, this issue is quite common. Most likely, the exhaust pipe's mounting hangers have aged, causing the metal pipe to loosen and rub against other components during acceleration. It could also be loose screws on the chassis guard plate, shifting and scraping against the drive shaft when bumping. If it's the sound of a slipping belt, it usually occurs during cold starts, and the sound is located at the front of the engine bay. I recommend first opening the hood to check the belt for wear, then getting down to observe if there's any leakage or rust at the exhaust pipe joints on the chassis. Lifting the car for inspection makes it easiest to locate the problem. Delaying this issue could lead to damaged heat insulation cotton or a perforated muffler, resulting in higher repair costs.

[Bustamante]

When driving my father-in-law's old car, I encountered a metallic noise from the throttle, and the key is to identify the source of the sound. If the noise comes from the rear of the chassis, it's usually due to aging gaskets at the mid or tail section of the exhaust pipe, where metal-on-metal contact creates a particularly harsh sound. If the noise is at the front of the car, it might be an issue with the air conditioning compressor bearing or the alternator pulley. The most unusual case I've encountered was internal ceramic breakage in the catalytic converter, where small fragments vibrated and scraped against the metal shell when accelerating. This situation requires immediate inspection, as it could block the exhaust, affect engine performance, or even damage the engine.

[LeElena]

This is a common issue I encounter during car repairs. Harsh metallic noises typically fall into two categories: loose exhaust system components and abnormal drivetrain parts. A squeaking sound occurs when the exhaust pipe gasket deforms under high temperatures, and cracked exhaust manifolds in turbocharged cars can produce similar metal-on-metal scraping noises. The other type involves loose flywheel bolts in the transmission, particularly noticeable during acceleration in the clutch engagement phase of manual transmissions. The most frequently overlooked cause is deformed brake rotor dust shields - even when not braking, body movement during acceleration can make the metal shield contact the rotating brake rotor. Checking these areas first can save significant repair costs.