Timing chains and gears are just fine like Zef said on 96+ year 3800's.

The plastic chain tensioner though...can wear, and chip off sometimes over time. But never have seen a failure or MAJOR problem from one doing that. Half the time, everyone is driving their car well past 100K miles with a chipped one, and don't even know it. They usually only find it, when they are doing a cam swap.

~F~