Bad alternator?

[Geotrash]

Any idea on part numbers? I think the tensioner is 12670574, but I can't seem to find a Tahoe specific part number for the idler pulley. Is it a generic part?

Edit: Is it one unit that contains both parts?

Idler pulley is: https://www.rockauto.com/en/catalog...,5.3l+v8,1433400,belt+drive,idler+pulley,6956

 

[17 Yukon Denali]

Alternator/ Belt/ Tensioner. These alternators have been known to seize up so hard that people mistake it for a seized engine because they can’t turn the engine by hand.

 

[adriver]

That video doesn't apply to you. The old style alternators used internal voltage regulators. The alt would constantly run, and would aim for a desired voltage (14.4v), then shunt the overage to not overcharge. Starting in 05, the alts had external voltage regulators, and are controlled by the BCM. The alternator is designed to fluctuate, and be ran at lower voltage. Instead of always running, it is designed to run when there is a need for more voltage. It does this to improve mpg. There is a short mention about it in the owner's manual. What you listed is within spec, and doing exactly what it's designed to do. Nothing you have said so far is a problem with the alt, (without knowing where the noise is coming from).

 

[bdbull]

Update on this...

Had to run a little longer on the bad alternator because I ordered the wrong part the first time. Wife drove home on Monday and got a message that she had no power steering. I read that the power steering on these things are electronic so that made sense to me. Got the correct alternator in yesterday and put it in. Had some trouble putting it in as it was a little wider than the mount it was going in so I had to sand it down a little to get it to fit. Hooked it up and it's been good so far. Battery gauge in the truck jumped right back up to the middle when I cranked it. Will continue to monitor, but I'm hoping this is behind us now.