3FE alternator rattling

[The Snake Pit]

I recently developed a gnarly under-hood rattle when my 91 is put into drive or reverse. I was able to get under the hood with my kid standing on the brake and observed the alternator shaking like crazy. I pulled the fan and WP pulley and tightened every bolt that even had the appearance of being connected to the bracket, but no joy, the rattle remains as loud as ever. One thing I did notice was the absence to the long tensioner bolt at the back of the alternator. Im assuming the PO lost it. Everything else was intact and functioning. I recently had the alternator tested and it passed (separate issue with the battery). Can the rattle be from the missing tensioner? Or is it possible the alternator is having a physical breakdown somewhere before failing electrically? Id like to know before getting a "new" alt from Toyota. Ive also seen the tensioner bolt described as "unobtainium". I guess I can start doing a parts rain dance now, and start hitting the local junk yards...

 

[SUMMIT CRUISERS]

I recently developed a gnarly under-hood rattle when my 91 is put into drive or reverse. I was able to get under the hood with my kid standing on the brake and observed the alternator shaking like crazy. I pulled the fan and WP pulley and tightened every bolt that even had the appearance of being connected to the bracket, but no joy, the rattle remains as loud as ever. One thing I did notice was the absence to the long tensioner bolt at the back of the alternator. Im assuming the PO lost it. Everything else was intact and functioning. I recently had the alternator tested and it passed (separate issue with the battery). Can the rattle be from the missing tensioner? Or is it possible the alternator is having a physical breakdown somewhere before failing electrically? Id like to know before getting a "new" alt from Toyota. Ive also seen the tensioner bolt described as "unobtainium". I guess I can start doing a parts rain dance now, and start hitting the local junk yards...

How's the tightness on the pivot point bolt that takes a 14mm socket and a 6" extension from under the truck? I would also check the bracket mounting bolt(s) where the tensioner pulley mounts to.

 

[The Snake Pit]

The bracket bolts were a little loose, but nothing extreme. I replaced the water pump about 6 months ago, so I have a good idea as to whats bolted where and I'm pretty sure I got everything tightened down. There is no play in the alternator or fully bracket with the engine off, and only rattles at idle in drive and reverse.