1. Worn Engine Mounts: Worn or damaged engine mounts can cause the engine to move excessively within the engine bay, leading to a knocking sound.
2. Piston Slap: Excessive clearance between the piston and the cylinder wall can cause a knocking sound during acceleration. This issue is more common in older or high-mileage engines.
3. Connecting Rod Bearings: Worn or damaged connecting rod bearings can generate a knocking sound as the engine accelerates. These bearings help connect the pistons to the crankshaft.
4. Timing Chain or Belt: A loose or worn timing chain or belt can cause a rattling or knocking noise, especially if they have jumped or skipped a tooth. Failure of timing belt parts also causes significant damage if the engine keeps running.
5. Loose Components: Any other loose components in the front end of the car such as heat shields, body panels, and suspension components can vibrate and produce a knocking sound during acceleration.
6. Faulty Ignition: Irregular ignition or incomplete combustion can also result in a knocking sound because of variations in cylinder pressure. Issues with spark plugs, ignition coils, or fuel injectors may cause these symptoms.
It's important to have the knocking noise diagnosed by a qualified mechanic as soon as possible. Ignoring such noises may lead to more severe issues and costly repairs in the future. The exact cause can be determined through visual inspection, engine diagnostics, and possibly a road test by the mechanic.
