"Hissing" noise from transmission

[ccrse]

I bought a 2000 Ranger w/ 90K miles on it a few months ago.

This morning, it started making a "hissing" sound when I put it in 2nd gear. The noise also shows up in 3rd, but I can't hear it in any other gears.

Transmission appears to be an M50D-R1. No signs of a leak - everything is clean and dry. Not problems of any kind with the truck until today.

Noise is only present when truck is moving, and in 2nd or 3rd gears
Loudest in 2nd, quieter in 3rd

Noise varies with vehicle speed

Noise does not seem to vary with load, engine RPMs, clutch in/out

There was no sign of any problem before this morning. My wife *did* borrow the truck yesterday, and she's can be pretty brutal with a clutch...

Any suggestions what I might be dealing with?

 

[reno]

I know I posted about my tranny making a hissing noise, and was told it is the beginning signs of the bearing going out.

http://www.therangerstation.com/forums/showthread.php?t=10436

That is the post on it, amongst others.

 

[ccrse]

Reno,

I had seen the post that you referred to. My first thought was also that it sounded like a bearing, but I'm a bit confused by the fact that the noise only shows up in two of the forward gears.

Since the noise doesn't change w/engine RPMs, it shouldn't be an input shaft bearing. An output shaft bearing would make noise any time the truck's moving - not in just a couple of gears

I'd expect that other bearings would show up on, say, all the forward gears (4th excepted, perhaps). I'm pretty ignorant of transmission internals, though, so I could be wrong on any/all of this.


I'm sort of hoping that someone with more experience will find this before I start looking into this over the weekend.

Thanks.