Strange noise from engine..."Whirling" sound

This is for a 2015 Thor Majestic 28a Class C RV with a Ford e450 V10 engine. It is a previous rental. I've owned it for about 30,000 miles and it now has 140,000 miles on it. Back in Feb 2021 I had an RV mechanic go through for a yearly maintenance check (tires, brakes, fluids, belts, radiator, etc). It was in great shape and the only recommendation was to replace the Transmission fluid (which I had them do). That was 2000 miles ago and it has been running great.

In May of 2020 (10,000 miles ago) it developed a leaking manifold. I brought it to one of my RV shops and they pulled the engine, replaced the manifold, and while they were doing that they also replaced all sorts of stuff since it was easy while they had the engine out. (Side note: It might be questionable that they had to pull the engine, but 5 of the 10 manifold bolts were snapped and they said it was the only way they could get them all out and replaced.) For the last ~10,000 miles since then it has purred like a kitten and driven well.

The RV recently came back from a 1000 mile trip with no issues I'm aware of. After the RV sat for several hours (presumably cooled down) I went to drive it 3/4 of a mile away to where I store it. When I started it up, I could immediately hear that something in the engine didn't sound right. It sounded a little bit like a leaking manifold, except it wasn't the deep rumbling sound of a leaking manifold. It was more of a higher pitched whirling sound. Maybe a rubbing sound? As I accelerate, the whirling engine noise gets louder.

Here is a youtube video so you can see/hear the sound.
https://youtu.be/MSFO99BWk1c

In the video, about two thirds of the way through I slow down and then accelerate into a right turn (that’s where you can hear the noise the best). Note: The yellow light on the left side of the dash is the Tow/Haul indicator (not a warning light).

I have an OBD reader on the RV and it tells me that ALL SYSTEMs are okay and no error codes. All of the following say “No Problems Detected”:

- Power Steering System
- Engine Management System
- Brake System
- Internal Control System
- Idle Control System
- Generator System
- Engine System
- Intake System
- Electrical System
- Turbocharger System
- Fuel System
- Cooling System
- Ignition System
- Emission System
- Fluids System
- CAN System
- Transmission System
- MIL Control System

I do not live in cold temperatures...all of this is happening with outside ambient temperature around 70 degrees F.

Here is likely a clue that hopefully will help you (help me) pinpoint what the problem could be… The engine makes this noise ONLY FOR ABOUT THE FIRST 3 BLOCKS of driving when cold. Then the noise seems like it completely disappears and the engine sounds perfect. I’ve let it cool down and then driven it 3 times this week and each time it made this initial high pitched whirling noise for about the first 3 blocks of driving and then it went away. Tonight when this happened again (noise went away after 3 blocks), I pulled over and turned off the engine and let it sit for a couple minutes. When I started it up again it sounded fine and didn’t make the noise for the rest of the short trip to put the RV back in storage.

I checked the radiator fluid, power steering fluid, and oil and they all look perfect. I didn’t check the transmission fluid.
I don’t think the engine is “Warming Up” in just 2-3 blocks so it might not be “correcting” itself via some heat related thing. But I can’t help but think maybe there is some sort of fluid/oil/etc that settles when the RV sits for a few hours and then when starting from a cold engine/start after just a few blocks things become lubricated once again (due to the engine movement/cycling or fluid pumping) and then the whirling/rubbing noise goes away.

Any thoughts what this can be??? Where should I start my investigation?

Thanks in advance!
Chris