A while back i noticed a clacking sound comming from the pulley side of the engine, and have narrowed it down to the crankshaft pulley an/or harmonic balancer. The sound is goes away over around 1200 rpms, but that could just be from in increase of the frequency, making it inaudible. Is there any specific reason it would be making that noise, and if i plan on replacing the parts, does that mean i'll just need a new harmonic balancer, or a pulley as well?

 

Yes, the rubber bushing may be worn out. This can allow the pulley too slip relative to crankshaft. It's a subtle progressive problem that doesn't leave major clues.

Eventually you may get a run down battery w/ no ALT light. I had this happen on an Acura TL, and resulted in terrible downhill problem when I let a shop try to fix the car for my son (in CC, tx). Have someone you trust, or yourself remove and examine the harmonic balancer or crankshaft pulley to be sure.

good luck