Torsional vibration damper failure signs

Torsional vibration dampers are crankshaft pulleys with a rubber damping element between the two main metal parts. They were introduced to absorb vibration from the crankshaft and produce much smoother drive system operation and are found on most late models of passenger cars and light commercial vehicles.

Without their damping effect, the vibration would be transmitted through the accessory belt drive system and can lead to premature failure. It is also worth noting that as the timing belt is also attached to the crankshaft, a malfunctioning harmonic balancer would also have adverse implications for the synchronous belt drive system. So, replacement is required when the harmonic balancer is no longer able to provide reduction of vibrations due to wear.

Furthermore, when a torsional vibration damper has reached the end of its service life Gates recommends that all wear parts are replaced at the same time to ensure the best long-term solution.


Watch out when inspecting torsional vibration dampers since the damage is not always obvious:

1. Micro cracks in the rubber damping element

Appearance: There are fine cracks in the rubber.

Cause: Hardening of the surface due to ageing which ultimately leads to failure of the damper.

Solution: Replace the torsional vibration damper.

Note: 45° angle cracks are a typical sign of wear due to excessive engine idling.


2. Deformation of the rubber damping element

Appearance: The ring of elastomeric material is clearly deformed. The deformation initially becomes visible on the rear side of the damper. This kind of damage is frequently overlooked in inspections because the pulley itself is often not removed for visual inspection purposes and is only examined from the front.

Cause: The rear side of the damper is situated closer to the engine subjecting it to more heat and contamination.

Solution: Replace the torsional vibration damper.

3. Rubber separation

Appearance: The rubber loosens and gets stuck between the pulleys and the belt.

Cause: The harsh working conditions (vibrations, shocks, heat and contamination) inevitably affect the damping device. Over time, this results in rubber separation: break-outs in the rubber itself as well as separation from the metal.

Solution: Replace the torsional vibration damper.

4. Damaged slotted holes

Only for those types of torsional vibration dampers that have wear indicating tabs which allow checking the angular displacement of the rubber versus the pulley.

Appearance: Clear contact marks from the metal wear tabs in the slotted holes.

Cause: The metal wear tab is prevented from contacting the slotted hole until the rubber damping element has severely worn out. Once worn out, the tab repeatedly hits the slotted hole leaving clear contact marks.

Solution: Replace the torsional vibration damper.


5. Damaged bushes

Appearance: Cracked or split bushes which will result in strong vibrations.

Cause: Wrong torque settings at installation.

Solution: Replace the torsional vibration damper.

Note: Exact torque settings are required for every model.


6. Total failure

Appearance: The torsional vibration damper physically falls apart. It can also come off the engine completely, resulting in an immediate breakdown and collateral damage.

Cause: Excessive vibrations due to lack of maintenance.

Solution: Replace the torsional vibration damper and make sure to check all the other components for possible damage. Check whether the engine vibration levels are within tolerance. Make sure the dual mass flywheel and overrunning alternator pulley function properly.