The first sign of wear is “noise”. A tensioner that sounds bad usually is bad. While the engine is running, listen to hear if any noise is coming from the timing cover or front assembly. Bad bearings make a high pitched “whine” or “growling” noise after the engine has been started. If there is noise, and it is identified as coming from behind the timing cover, you should: Remove appropriate components in order to remove the timing belt and check the idler pulley for failure.