Motor Mount (Engine Mount)

What it does

Motor mounts are rubber-and-metal sandwiches that bolt the engine to the car's frame. The rubber absorbs the engine's vibrations so you don't feel every combustion event through the seat. When the rubber deteriorates — it cracks, hardens, or collapses — the engine can move and rock freely. You feel this as a clunk or lurch when you shift gears, heavy vibration at idle, and sometimes a thud when you press the gas. A broken mount can let the engine rock far enough to damage coolant lines or the exhaust.