Just as the title states, I am getting multiple and strange sounds coming from the pulleys. It almost sounds like a combination of a bad idler and a bad automatic drive belt tensioner. However and also, about 3 years ago, the previous engine spun a rod bearing and it was replaced by the current engine (an online bought rebuilt engine). There didn't appear to be any issues after installation, but now, it appears, that there is a slight wobble in the crankshaft pulley and maybe that is accounting for some of the knock-like rattle noises? I am honestly lost on this one, and any help or opinions would be appreciated before I start playing the process of elimination merry-go-round. Thank you.

 

You need to buy a cheap Stethoscope & listen to each pulley.

 

Just bought a cheap stethoscope off harbor freight, should be here in a couple of days. Thank you.

 

In the mean time, squirt a shot of WD-40 on the belt, flat and ribbed sides. If the bird chirp changes or goes away, replace the belt. I've heard alternators rattle like that but it's rare, usually tensioner. Grim's right though, cheap stethoscope will take all the guess work out of it.

 

Update: Got the stethoscope, and some bad news. It was the harmonic balancer. Looked high and low for a Dayco PB1386N to no avail, apparently the harmonic balancer for this car has been discontinued. Ended up overnighting junk yard grab. Will update once it's in. Hopefully, it is not the belt as well, as it is only ~4 months old or so.

 

The balancer you say? huh, Not a common thing for sure.

 

Update: Replaced harmonic balancer -> tensioner idler started squeal -> replaced auto drive belt tensioner and idler pulley -> alternator pulley started squealing -> replaced alternator -> silence.