What is this engine noise?

https://youtu.be/c0kW2XyT7rc?si=Mdjh8HmxtZRBB7a4

Maybe not the right place for this, but if you're like me you enjoy figuring out problems. 

2019 Chevrolet Express with the 6.0 V8, 50K miles. 

I bought this a month ago and recently started noticing this buzzing noise at ~2K rpm, send to be coming from the passenger side of the engine. It sounds like a hydraulic pump sucking air, like a failing power steering pump, but it still happens when the serp belt is off, which eliminates all belt driven accessories and pulleys except a/c (separate belt), which I'll will try next when it dries out around here.  

It's engine rpm dependent, load/no load has no effect, a/c on/off has no effect, moving/stationary/in gear/park has no effect. Seems to be mildly engine temperature sensitive as it doesn't happen until the engine has been running for a minute or so then it starts.

Transmission?

Hmm, that is a scary thought.

It sounds like it's coming from ahead of the transmission, I'll poke around more to pinpoint the source. 

The power steering pump on our vans is notorious for making noise.  Mine sounded a lot like that when I bought it with 80k, then it turned into a constant whine, then it started leaking.  I replaced it with a new one from the GM parts counter, and it whined out of the box.

It's something different because of the hydroboost brakes.

Hard to tell from the audio, but it could also be a random shield that is rattling at a certain RPM.

In reply to Curtis73 (Forum Supporter) :

You win. I think it's the p/s pump. Your reply got me to dig back in again. 

I checked the atf, it was a little low (I flushed it a few weeks ago) so I topped it off, no effect on the noise.

I pulled the fan clutch, no effect on the noise. I then alternated back and forth: belt on, belt off, belt on, belt off. It only happens with the belt on. I've already replaced the w/p and all pulleys, which leaves the alternator and p/s pump as "old", or a bad new pulley, but this happened with the old ones too so that's unlikely. I'll flush the p/s fluid today and see what happens. 

​​Last time I was in there the kids were playing outside and  majorly distracting me, I think I got tripped up when I was testing with belt on and off that time. 

In reply to drewohio :

I've yet to be in an Express/Savana that didn't have a P/S whine.  Back when I drove buses, all of our GM van-based short buses had a whine.

Not sure why, but it must be something to do with the hydroboost.

I flushed the power steering fluid on Sunday which had no effect, but the old stuff was pretty dark so needed anyway.

I replaced the power steering pump this evening and just got back from a long test drive with the van. I am unable to reproduce the sound afer replacing the pump. I was really having trouble thinking it was the pump with only 50K miles, but that was it.

Good sleuthing.

I hope it doesn't come back, but honestly speaking, don't be surprised if it does after 20k.  Hydroboost does a number on these pumps for some reason.

Maybe I'll add a proper cooler to the system, I can't imagine that loop does much.