So i went to jumpstart a buddy and when i popped my hood i heard the most god awful noise coming from my alternator. It isnt a constant sound however its almost rythmic. Like off an on, sound like a knocking/grinding accompanied by a slight squeal (very very slight)

i held my hand on the alt and when it made the noise it vibrated so im 99.9% sure its that or the belt tensioner next to it.
i just want someone elses opinion
what is failing?
how detrimental is it?
and most importantly am i right?
( i dont have a belt over the ac pump or power steering…)

 

Was your AC on at the time; if so, possibly the ACClutch+Compressor cycling On\Off & loading\unloading the belt?

PS: never mind, now I see your note tha you don't have an AC Compressor.
Yep, Alternator noise aint natural; could be a BeltTensioner going bad; how old are these items.

 

probably from 95’ with the truck😭

 

Remove the belt and manually spin both the tensioner and alternator, you WILL hear which one it is