Really strange new issue... Help?

[1997SCEBFEX]

i'm sure you checked all your pulleys and serpentine belt routing? it doesn't seem like a belt squeal, but hard to tell from where I sit. is your belt excessively tight with the new tensioner?
it seems to occur from your video in the 2500-3000 rpm range?
any other rarities?

PanHandler.

late minute thought: when one of my supercharger idler pulleys was starting to 'puke' its bearing, it gave off a similar noise. Perhaps alternator or p.s. pump?

 

[Jeff532003]

Props to Panhandler and Lightning for calling it. I was fairly certain it was a something in the belt drive but I've never heard anything fail so spectacularly. That harmonic noise so was loud when it hit you could feel it resonate through you.
So anyway I'm 99.9% certain it's fixed. Tomorrow morning on cold start will fully confirm. I finally have a night off from work so I got up this afternoon and went to work on it. This morning I was fairly certain I'd pinned it down to passenger side front which left tensioner idler pully and AC compressor but any noise I heard was so faint I wasn't certain. Fired it up this afternoon and definitely heard a faint intermittent little squeak randomly as it idled. I'd already spun the idler and it felt fine attached but I knew it wasn't AC compressor as no change when I turned it on and engaged the clutch. Figured it had to be idler so I pulled it up and sure enough spinning it in my hand, the bearings felt like someone dumped sand in there. Trip to auto zone, changed it in their parking lot and it seems all good now. Nice and quiet and no noise detectable. I'll update when I'm certain it's fixed but I'm fairly sure now. Thanks so much for all your replies.

 

[Lightnig]

Good to hear.

Let us know after you've lived with it a few days and are certain it's fixed

 

[1997SCEBFEX]

Good news for sure & hope you both diagnosed/fixed it up.
Nice feeling inside when you can accomplish things on your own & glad we were able to virtually help.

PanHandler.

 

[Jeff532003]

Just wanted to update this in case anyone else has this issue. This was one of those things were fixing one issue created another. Replacing the broken belt tensioner allowed my belt to actually run tight instead of half slipping like it was when I got it. Replacing that started the squeal. I noticed a squeak coming from the idler pully so I thought there was a good chance that was what was causing the noise. I replaced it and for reasons unknown to me it didn't squeal for about a week but then started up again. Using my stethoscope I still could not definitively hear the squeal as it would not happen unless conditions seemed to be perfect. I did however hear what sounded like a lot of grinding bearing noise coming from the alternator. I tried to convince myself it was just the brushes spinning but it just didn't sound like that so I decided I'd replace it and if the new one had the same noise is just return it. Well low and behold I hooked up my brand new, not reman, alternator up and it was quiet as could be with the stethoscope. Over three weeks now and the squeak is fully cured and a few other broken parts where replaced so no lose there either.
So if you ever experience this awful noise in your truck check the alternator. I'd never of guessed it could make that god awful noise so loud in the cab of the truck but resonating metal acting as an amplifier is confusing like that.

 

[Lightnig]

Good news, glad to hear that you got the issue fully resolved.

And thanks for taking the time to give us the update

 

[uscgmac]

I know this is an old post but I'm glad I found it. I have the same exact noise to a tee. It is so exact that I don't even have to try and recreate the noise. It's as if I'm driving my own truck. This started a couple days ago when it got cold out for the first time this year and only does it intermittently. I'm figuring that the pully is in the beginning stages of going because it just started doing it and it's not as frequent or as loud as yours but I'm sure it will progress. As far as the alternator it seems as if the one I have looks fairly new to begin with being it's clean and new looking. I bought the truck used without much history so who knows. This post helps a lot.

Sent from my SM-T350 using Tapatalk