When you're asking an engine-related question we need to know which engine you have. You can tighten the center bolt with a large ratchet or an air impact gun. If you have a manual transmission, put it in the highest gear to hold the engine from turning. If you have an automatic you will need an impact gun because there's no easy way to hold the engine from turning.
It is much more common for the outer ring to let go. Since I don't know the engine size I can't look up the harmonic balancer. Some have the pulley cast as part of the outer ring which is glued to the center hub. When that glue lets go all you can do is replace it. Auto parts stores have large catalogs with balancers, (also called vibration dampers), for all car brands.
Some applications use a separate pulley bolted to the balancer, usually with six bolts. All of them would have to come loose to cause a problem. Those must be tightened by hand to avoid breaking them off.
Sunday, May 26th, 2013 AT 4:32 PM