Truck has high pitched whine when slowing slightly or holding speed. Increases until engine pushes hard again. Everything must be at operating temperature and will do it in 4,5, or 6. It doesn't do it always, only when driving lightly. Take it out of gear even when holding engine rpms and it stops almost instantly.

First thing I tried was changing tranny fluid. It shifts a little better but the noise is back. 108,000 mi on truck.

Any Ideas?

Thanks

 

I'd first pull the center stuff off the floor and check the inner boot. When they tear, it can broadcast all sorts of bad sounds into the cab.

 

Possible throw out bearing?

 

I thought throw outs were when there was a grinding noise with the clutch depressed?

 

your truck has a dual mass flywheel. you got more miles out of it than most. all of ours failed between 35,000 and 75,000 miles and that is about average. southbend sells about 50 kits a day. get the conofe kit. the g56 transmits the engine noise due to its design and that is why they went to the dmf but the dmf was of faulty design. the new solid flywheel if going to transmit the noise so do not get excited when it is noiser than it is now. also when the g56 is out look at the front seal, the dmf knocks the seal out of every one we have seen. before you install the shifter add one quart over full

 

The dealer took a look at it. I was able to make the noise for him at 40 and 50 mph in 6th. They also think that it is in the transmission, but don't know what it could be. He said it sound like singing from the gears.

Much to their credit, they didn't just tear into it without knowing what to look for. They want to ask other mechanics in the area as well as the factory if anybody knows what the problem could be.

Meanwhile they gave it back to me and I'll wait.