Quiet "chugging noise" at idle from engine bay

It's an '01 330i. The last service record from bmw dealership that the p/o provided states the following:
"check out engine noise, possible water pump, pully, or ???.
Water pump bearings failed.
Belts are glazed, slight play in belt tensioner.
Replaced coolant, water pump, and both drive belts"
This was the end of march, car has been driven another 3,000 miles since.

I don't hear the noise on a cold start, once the temp gauge is in the middle its noticeable. I first noticed the noise when I pulled into a parking spot with the windows down on a quiet street. It's auditable in the car with the fans and radio off if you are listening for it.

At idle the engine speed is constant, doesn't vary at all. Lightly touching the throttle makes the sound go away.

I attached a photo of where the noise seems to be coming from. I've been searching around, and I dont think its a vanos related problem because I don't have any loss of power.