Purpose

The harmonic balancer is a vibration damper within the engine, designed to reduce wear on the main bearings and journals and to prevent crankshaft failure. It also reduces the vibration and noise in the passenger area.

Structure

The harmonic balancer is comprised of three parts: the main hub, which is bolted to the crankshaft, the outer disc which has timing marks and pulley cuts for the belts, and the rubber ring situation between them, which dampens crankshaft vibrations.

Operation

When a cylinder fires, the connecting rod hits the crankshaft journal, and causes the crankshaft to turn, which puts a twisting motion on the crankshaft, first in the back and then in the front. The harmonic balancer allows the rubber ring to twist instead of the crankshaft itself, reducing stress on the crankshaft and vibration that would've been caused by the rear of the crankshaft snapping back in the opposite direction of the front.

Failure

The primary cause of failure is age. Over time, the rubber deteriorates and cracks, eventually separating from the metal sections and leaving the outer ring to spin separately from the hub. Failed harmonic balancers should be replaced immediately, to prevent crankshaft damage.

Replacement

Replacing a harmonic balancer is best done by a professional. Ensure that the replacement harmonic balancer is designed for the same engine as each harmonic balancer is specifically designed for a specific engine.

Source:

Car Parts Wholesale

2 Car Pros

Parts Train