Harmonic Balancers
Most engine makers warn you to change a balancer at 500,000miles. Had an ISX in yesterday. Owner said it had an engine knock. It did when you started it and shut it off. Not AS much when running. Owner had made a number of changes. We got lucky. Spotted a tiny crack in balancer. When we pulled it the whole center under the pulley was broken in a circle. If the owner had made another trip the damage would have been extensive, balancer on its own isn't free. Check them but really think about changing at manufacturer recommended interval.
Art Pfluger
Art Pfluger