My Navigator sat all day and its 25 degrees F out. I started it remotely and I start to hear a screaching noise coming midship. Its not coming from the engine but midship around the transmission area. After it warms up a bit the noise seems to go away.
This condition is not related to my prior issues or repairs. I heard this whirring a while back and now its simply got much louder.
Try a mechanics stethoscope on that to zero in closer. That sound will be vastly different as you get close to it. It might be a heat shield rattle but to me it sounds like some shaft scrubbing at the speed the engine is turning. Pulleys and serpentine belt tensioner bearings makes noises like that when they start to die ( as they often do) though you’d think that to be coming from the front of the engine. Still, noises can sound like they are coming from some other place sometimes.