Crankshaft Pulley
A grooved wheel attached to the snout of the crankshaft that drives the serpentine belt and accessories.
The crankshaft pulley (also known as the harmonic balancer pulley or crank pulley) is a grooved metal wheel bolted to the front snout of the crankshaft. Its primary role is to drive the serpentine belt or accessory drive belts, transferring the engine's rotational power to components such as the alternator, water pump, power steering pump, and A/C compressor.
On most vehicles, the pulley is integrated with a harmonic balancer (damper), which features an outer steel ring separated from the inner hub by a thick layer of rubber. This rubber damper absorbs the torsional vibrations generated by the engine's power strokes, preventing the crankshaft from twisting and breaking under stress.
Over time, the rubber dampening ring inside the pulley can dry rot, crack, and separate due to heat and oil exposure. When this happens, the outer pulley ring will wobble, slide out of alignment, or slip relative to the hub, causing belt squeal, accessory failure, or damage to the timing cover. A wobbling crankshaft pulley must be replaced immediately to prevent engine damage.