Numerous timing belts supplied to the automotive aftermarket industry do not adhere to OE specifications, carry "belt only" warranties and may leave service dealers at risk for expensive engine repairs, according to the Gates Corporation.
A timing belt failure can be a serious problem. Not only does it strand the motorist, but it also can cause serious engine damage. The high compression "interference," OHC automobile engines of today are smaller and lighter than their predecessors, with very close tolerances between the pistons and the valves. Timing belts synchronize the action of the pistons and valves in the combustion chamber, preventing them from occupying the same space at the same time. If the timing belt breaks, synchronization is lost, valves and pistons collide, and significant engine damage results.
Repair shops and do-it-yourselfers who install a timing belt that has a "belt only" warranty may be stuck for any related engine repairs if the belt fails.
The problem has surfaced due to the role of some "repackagers" in the automotive aftermarket industry. These companies buy up thousands of timing belts from various manufacturers, "rebox" them and sell them to parts suppliers. Some of these parts supplied to the automotive aftermarket may not meet the exacting specifications of today's modern engines. They may break or wear out faster than high quality, OEM-approved parts. Most importantly, these budget belts do not cover engine repairs or labor if there is a problem.
Changes in belt materials in recent years have led to the creation of long life belts made of a special high-temperature grade composite called "highly-saturated nitrile" (HSN), or EPDM. An HSN or EPDM belt appears no different than a chloroprene belt, but significantly outperforms in the high temperature engine compartments of modern vehicles. Unfortunately, tests show that some timing belts supplied by some "repackagers" are made of chloroprene when HSN or EPDM is required at the OE level. Chloroprene belts when misapplied can lead to premature engine failure and expensive repairs
If you are buying a replacement timing belt, ask the seller what kind of warranty comes with the belt and what exactly it covers. If it does not include a complete warranty, don't buy it. The risk is not worth it. Pay a few dollars more for a quality belt made of HSN or EDPM that meets OEM specifications and is backed by a parts and labor warranty.