GT451

My truck has recently developed a strange whining/hissing noise under the cab. If I had to guess, I'd say near the trans x-member.
It does it while rolling and quits when the truck stops. I've tried hanging my head out the door while rolling and can't at all pin point it.
I've also tried hitting the brakes, pushing in the clutch, putting it in nuetral, turning the steering wheel, deccelerating, accelerating, turning the key off and coasting, putting it in 4wd, and just about everything else to either stop or change the sound and nothing works. Only stopping makes it quit and that makes it hard to figure out.
Any advice? I tried searching and found nothing conclusive.
Oh yeah, when it first starts, it does this stuttering bit like off on off on and then just goes solid until the truck stops.
I looked at vacuum lines, ujoints, seals, checked fluid levels, and everything looks ok.
When this first started about two weeks ago, it was more of a quiet hiss, now it's a louder whining.
It is definitely not turbo or alternator related.

1-2-3

Throwout bearing maybe? Do you still call it that? The bearing used in the clutch assb.

GT451

The sound doesn't change tone or pitch when I step on the clutch. I thought about that too.
It's still called a throwout bearing as far as I know.

dssimecek

The throwout bearing would whine or make noise anytime the engine is running the flywheel is turning. Get a brave volenteer to lay under the truck as you drive forward.
Let us know what you find, good luck.

getblown5.9

carrier bearing in the driveshaft...only part that is ALWAYS moving when the trucks is moving whether in gear out of gear, 4x4 2x4

my old man had one go bad on his old 95 and it made the same noise

ib516

This is my guess too. Right under where the cab meets the box.

GT451

Carrier bearing would be a great guess but my short bed QuadCab is not so equipped.

It still makes the noise with the engine off, in neutral, coasting, at which point the flywheel, clutch, t/o bearing, and pilot bearing should all be sitting still.

Thanks guy's, keep the suggestions coming.

johnh

i was hauling some firewood and developed the same noise, i crawled under the truck and spotted a small piece of wood jammed between the cab & bed ,it was rubbing the drive shaft removed it after a hard time( it was really jammed in) and noise left

dieselrob

I would check the u joints or carrier bearing. I just did u joints on my dakota, the would squeal like bad breaks up till 35 40 mph befor it stoped.