Throw Out Bearing?

The other day out of no where I heard the most ridiculous and loud sound as I was pulling out of the parking lot on a long rainy day. The truck had been sitting in the parking lot for 8+ hours.

It clearly came from the front of the truck and my first thought was maybe something in the front axle/steering. It was a loud whine/grinding sound that stopped when I came to a stop. Also, it didn't have anything to do with revving the engine (in neutral) only forward motion in gear.

I took it to someone and they immediately heard it a said throw out bearing. BTW, the current bearing is less than 20k miles along with the clutch and flywheel that were replaced at the same time.

On the way home...it quit. I had someone take it to the transmission shop for me (I was not available during business hours). They called and said it was the rear end differential. Now .... trying to keep this short, yes there is a whining sound from the rear end and has been for years so I don't doubt this is problematic but when I came back to do a test drive with them...the sound I heard was not there ... only the sound for the rear end. The sound I heard was many times louder and clearly from the front end.

Any thoughts? I know this is vague. I just took the truck back from the shop and drove it fro 30+ minutes with no hint of the same sound again. I can't afford to break down and am cautious to drive too far as I have had a transmission completely melt down on me before and it was no fun!

1999 Ranger 4.0
Manual 4x4
5 speed rebuilt transmission (~2.5 years and 40k miles on it)
New clutch/slave cylinder/pilot bearing/flywheel (5 months and 5k on it)

Just a hack here so I may be off base.

I associate throw out bearing noise as relating to when the clutch is depressed. Not while driving.

I had what I thought was a problem with my throw out bearing, a grinding sound when I pushed in the clutch which eventually turned into an irregular metallic pings and such (sounded like bearing bouncing around) and one day while hearing those, it went clunk and stopped doing that, and then it didn't make much noise at all when I would depress the clutch but after 4 or 5 seconds it would turn into a squeal (I imagined it was races running together). The first stuff started around 95K miles and the clunk was around 105K miles so it was a protracted period.

All this ONLY happened with clutch pushed in. I did have some issues with clutch disengaging after that, if I used the clutch too much. I modified my driving so as to use the clutch minimally which seemed to help (as well as avoid the squeal) and I eeked another 80K miles before I had to get the clutch replaced because it started slipping all the time.

So if it happens as you drive forward, clutch not pushed in, it doesn't sound like my experience. Of course there is a chance that mine wasn't a throw out bearing. At the time (when at the grinding stage) a friend told me it was.

It isn't surprising that the shop zeroed in on the rear end issue if it had stopped the noise before getting it into the shop.

I've had very poor results with shops and anything that isn't clearly demonstrable and I tell them how, unless I demonstrate it myself somehow they end up focusing on something else.

May sound pretty dumb or off the wall, but I had a ridiculous noise in my B2, that happened then after that a terrible rattle continuously which turned out to be the PO had done some work at some point and didn't bother torquing the bolts to the flywheel back down so the flywheel came lose.

Possibly you had a flywheel bolt come lose get stuck in something then finally fell to the bottom of the bell housing so the noise went away. Could have also been one of the springs in the clutch disc broke and got stuck for a little bit then broke lose and fell away.

My throw out bearing in my 99 Dodge Ram failed (ok well more like exploded) which caused a terrible screeching noise clutch pedal in or out didn't make a difference. Drove it to the shop and had to have the throw out bearing, and the clutch disc replaced. Then that's where everything went wrong with that truck and my dealings with the dealer. They got the idea to resurface the flywheel at that point and of course didn't shim and re-balance it and you can only imagine the ending of that...wait I don't know I don't have the truck anymore LOL.

Well, so far, the sound has not returned but I am paranoid and am avoiding long drives in the AM so I don't break down and be late to my training which is super critical to my career success and can't be late/miss a day. Luckily, I have family I can stay with down the street from where I need to be each morning.

Almost 2 years (25k miles) later...no problems, no weird sounds. Crazy!