Strange noise from NV4500

[greengreer]

Got in my truck this morning and noticed an odd noise almost like radio static, but because I had the windows up I
I really didn't think much of it.
When I pulled back onto the road from work I noticed a strange buzzing noise coming from the transmission. It sounds alot like if you where to stick a playing card into a fan. Like a loud buzzing, raspy sound.
The noise seems to come and go but it is more often there than not. I also noticed when I push in the clutch it seems to sound like it winds down with the engine.
I have no idea what this could be (release bearing?) everything shifts fine but it definitely sounds like something expensive is about to kick the bucket.

Any ideas as to what this could be?

[a5150nut]

I'd be pulling it real quick to see where the noise is coming from. I lost mine several years ago. No warning, just driving along and it seased up. Pilot shaft welded to the bearing. IIRC i replaced the pilot shaft, counter shaft, assorted bearings, and seals. You might check the aluminum cover on thee rear. 5th gear sometimes works loose in there. Drivetrain.com is a good source for parts and information.

[chevytuff]

At the very least pull your shifter off and see what your fluid level is, If it is below your input shaft you very well could have a toasted transmission.

[a5150nut]

Mine has a check plug on the side of it. Lot easyer than removing the shifter.

[greengreer]

Thanks for the replies.

So I drove to work and back today (about 30mi round trip) and noticed the noise to be fairly constant, but especially audible between approximately 1700-2000 rpm, especially in fourth. Going up my road to the house in first it was very noisy, but not really a constant sound. It would fade and come back.

I am thinking (read: hoping) it is a pilot bearing, although it doesn't quite have a bearing sound to it IMO. I am pretty sure it is not the clutch itself because there is no slippage whatsoever. It shifts fine, tested the synchros out and they seem to be fine. The tranny definitely needs a fluid change (not that it is acting up but I am unsure as to the last time it was done).

Keeping my fingers crossed I won't need to do a rebuild. I was hoping to use my refund money to do a db2 swap but I guess we will see.

As of now the truck is going in to get looked at tomorrow, I wish I had time to diagnose it myself but it doesn't look like that's gonna happen.

I will keep you all posted.

Thanks for the replies. Keep 'em coming.

[greengreer]

To update the thread:

The transmission was pulled, pilot bearing was shot. Along with the bearing, in went a new clutch, which was also shot, and a new flywheel as the original was badly cracked.

I am sure glad it wasn't the transmission, although all said and done it was none to cheap.

Thanks to all for their replies.