If your vehicle is showing loud metallic rattling noise when accelerating, here are the most likely causes and the parts you'll need to fix each one.
Heat shields often rust around their mounting points or have loose bands. As engine RPMs increase, the specific vibration frequency causes the thin metal shield to rattle intensely against the exhaust pipe.
Often described as 'marbles rattling in a tin can', this occurs when the air-fuel mixture ignites prematurely under load. It can be caused by low-octane fuel, carbon buildup, or failing ignition components.
The internal ceramic honeycomb structure of the catalytic converter can break apart over time. Under acceleration, the increased exhaust flow causes these broken chunks to rattle violently inside the metal housing.
Missing rubber hangers or loose exhaust clamps allow the exhaust pipes to strike the vehicle's underbody, heat shields, or crossmembers when the engine torques up during acceleration.
When mounts fail, the rubber insulators tear. This allows the engine to shift excessively under acceleration, causing metal brackets or engine components to grind and rattle against the chassis.
A stretched timing chain or a failing hydraulic tensioner will slap against the engine cover or plastic guides. This creates a harsh metallic rattle that increases directly with engine speed.