Can't figure out what this noise is

If you're trying to diagnose an unknown noise, I highly recommend two things: turn the engine's sound volume off and run the loco by itself.  There is so much diesel sound and wheel noise in the video that I can't pick out the sound you're talking about.

I had a similar scenario with a Lionel after I removed the trucks. Turned out to be not enough lubrication where the drive shaft met the gear in the truck.  

I will make another video.  I thought the same thing about the driveshaft, I lubed the bearing and the coupler where the truck attaches.  Same result.

Here is a video of just the Locomotive, seems louder when there is a load on it.   https://youtu.be/p9VqqNIfj-M

Are the pickup rollers turning freely? sounds like a dragging roller. Maybe give them a lube with graphite or neolube.

franktratin

That's a   tough one... Makes you wonder what type of track (I'm guessing sectional) and as Franktrain point out... Are the rollers actually rolling . Rough track joints?  Hard to tell.

Yes, I checked the rollers, they seem ok.  If the track was the issue, I would think the other locomotives I would do the same thing, I have about 10 others, no issues.  Has me stumped too.

Do know that there is no gerbil involved...?

Sorry - seriously, I can't tell much definitive about the sound from your video, but I have had a diesel or two that made a funny, "rustling" noise, and when I took off the shell, I found that a bundle of wires was being rubbed by one of the flywheels. I tied them back (this would have turned into a true problem, eventually) and all was OK. 

I have also created this noise (and fixed it) when doing ERR command upgrades to diesels/electrics. 

Your problem does seem to be "minor" (not mechanical or electronic), but needs to be addressed before it's not minor anymore. And it's annoying as heck. Open it up and look - or is there a warranty "issue"?

Gents,

The mystery is solved.  I took the locomotive apart like D500 suggested, I thought maybe a wire was touching the flywheel.  While one was close, it was not touching.  Looked around inside and everything seemed ok.  The motors were smooth, the running gear was smooth.  I then put it back together, and was just inspecting the bottom once again.  There are a set of free wheels in the back truck and front truck.  I spun them and one seemed a little different then the other.  Turns out the front set of free wheels were just slightly touching the metal sides of the truck.  Got out my c clamp and just ever so slightly brought them in a smidge.  Problem resolved. Thanks everyone for the suggestions!!

Glad to hear it; the more familiar we get with these little machines, the more control we have - and the less we spend on postage.