I've got a whine that goes up and down in pitch according to vehicle speed. Speeding up, slowing down with or without brakes doesn't effect it. Turning doesn't change it either.
Today I found the one thing that matters. I was coasting from about 50 MPH, and I put in neutral to quiet the engine noise. And, it disappeared completely. I slipped it back into drive, and the noise returned. I repeated the process to make sure. It goes silent when the trans is in neutral. Other than neutral any speed above 20 its clearly there.
The trans works as good as ever. As does the transfer case, axles, etc. While searching for the source, I've checked fluids in the front axle, T-case, rear end. I replaced the front hub/bearings, rotors and calipers. None of these mattered.
My first real clue is how its silent in neutral only.
Has anybody experienced or heard of anything like this?
Thanks, Ron

 

It sounds like transmission or differential gear whine. Appropriate lube levels won't stop it, although some additives might temporarily.

Reminds me of a story my uncle told. He stopped in at a car dealer one day and found him under a car on the lift. The dealer had the differential fill plug out and was stuffing a banana into it. Uncle asked him what he was doing. "The differential whines," he was told, "and this will quiet it down until I can sell it."

That was back in the 1950's, most likely bananas aren't your best bet now.

 

The banana story is the funniest thing I have heard in a few days.
I bet it does quiet things down for the first few miles!

 

I don't know enough to discount anything. But, what makes me think its "probably" not in the front or rear differentials is how it goes totally silent when its slipped into neutral. This happens at 50 MPH. or 20. When its put into neutral, there is about a 1 second delay. Then the noise stops like you flipped a switch. Put it back in drive and its like the switch was flipped back to noisy. There's no transition between the two conditions.
Does anyone know what stops near instantly inside the transmission when its put in neutral? It doesn't seem like the transfer case would react to neutral like that.....or would it?
I'm lost and I appreciate the help. Of the people here, I think about 90% know more than me about these things. All I can add is the truck does have 272K. But, it hasn't been loaded past 1/2 ton levels. All stock.
Thanks again....Ron

 

A long experienced trans shop owner told me he suspects a planetary issue. I'll pull the pan over the weekend and see how much of the upper half of the transmission is now laying in the pan.
I'll report my findings with an address for all donations.

 

... just a small update. Pulled the pan and everything looked good. New filter and fluid and buttoned it back up. Of course, no change. I'm in line to get it in a nearby shop to dig deeper. Will report the findings when I get them.

 

Most likely your rear diff is going out. Just hope it's not the carrier bearing race spinning in the housing. Dana 70 and 60 housings are no longer available. When the race starts spinning in the housing it increases back lash causing a gear whine. Common problem with Dana diffs. The way I check is pull diff cover then with pry bar check for end play in carrier, there should be no end play in carrier. If carrier moves side to side then race has spun in housing. I was able to save the housing on the last one I rebuilt by having housing machined by drive line shop that had the special machine for doing that. Had to remove rear diff and completely gut it to have machining done. The magnet in diff will usually have excessive metal particles on it if race has spun in housing also.

 

I put it on jack stands and crawled under it while running in gear. It seems to be coming from the transfer case. After reading up on problems I suspected the rear axle too. They have had more than their share of issues. I wonder if they started "saving money" on bearings.
But, so far the main suspect is the transfer case. Will know more soon.

BigIron70. I talked to another guy who had the same issues you described. He managed to catch it before the race spun. His was a '96 V-10. Quieter engine may have allowed him to hear it in time. His was low miles. Under 100K. That would be upsetting.

 

I'm having same issue on an 07 cummins with automatic. has a whine. it sounds like transfer case. don't hear noise from diffs or transmission. already done hub assembles on front. noise disappears if you drop it into neutral or down into 2nd. I suspect it to be a bearing possibly front output bearing. any help you have may help me and vise versa