Timing chains, with their thinner width, reduce overall engine length and are more durable than timing belts, requiring no scheduled maintenance. Timing chains do make more noise, have higher weight and higher cost than timing belts, though. Replacement timing chain kits can cost hundreds more than replacement timing belts, especially on OHC engines. This makes rebuilds of chained OHC engines very expensive.
However, over the past 20 years, belt applications have been fading out. The Achilles heel of belts has always been the recommended change interval, which, for the most part, remains around 60,000 miles. A timing belt is considered an internal engine component, mission critical, and most manufacturers offer powertrain warranties of 100,000 miles — they do not want a mission critical component that can’t make it through the warranty period.
Often maintenance neglect, head gasket replacement or related valvetrain issues will require the timing chain to be serviced. If you are replacing the timing chain, you need to look at all the related components.