Serpentine Belt Wear Inspection (September 01, 2010)

With the advent of new materials, the very nature of serpentine belt wear and failure has changed.

As R.K. Buzzell Ltd.’s Roger Donovan suggests, the ser- pentine belt has continued to evolve, mostly in materials and wear characteristics.

While neoprene belts were great by their contemporary standards–lasting up to 100,000 kilometres, cracking before ultimate failure (three or four cracks an inch and it was time to change out)–the ethylene propylene diene monomer (EPDM) belts introduced in the late 1990s wear down but do not crack or chunk as they approach their 160,000-km lifespan. This wear can be hard to inspect for.

To help, two major belt suppliers have come up with ingenious tools. Both Gates and Dayco have special belt wear gauges that can speed the diagnosis of a worn belt, and provide a means for shops to communicate with the consumer. In both cases, a small plastic gauge is used to measure the depth, evenness, and profile of the valleys in the drive side of the serpentine belt.

The reasons for this approach are simple: EPDM belts wear as they age. Although the ribs do not become shorter, material is lost in the valleys of the ribs, resulting in slip, noise, and hydroplaning. Wear can also be indicative of other problems, like pulley misalignment.

According to Gates, many warranty-claim failures on alternators and other parts are actually caused by worn or improperly adjusted belts.

Special thanks to Gates Corporation and Dayco Canada for information used in this sidebar.