My truck is a 2005 2500HD with the Duramax Diesel & the 6sp manual transmission. The truck now has about 10,500 miles, so is still under warranty.
For the first 9,000 miles, I did not hear the sound that I am concerned about. After that, with trans in neutral, and as the clutch is released (almost all the way), I begin to hear what I thought was a rattling noise. It came on suddenly (not too loud) & gradually increased in volume over time.
With the trans in neutral & the clutch fully released, the sound is gone. If I depress the clutch just a small amount, the sound returns. The sound can be heard either inside the truck or standing outside by the driver's door. It is not necessary to raise the hood or open the door to hear the sound.
I am someone who pays real attention to noises, smells, etc the truck makes. To me, the sound is unusual & subject for concern.
I took the truck to my local dealer. The service manager agreed something was strange & scheduled an appointment. When I brought the truck in, the diesel mechanic examined it and said the truck was making normal sounds. He said the sound I was hearing was "gears whirring" and nothing to be concerned about.
The sounds are now just a bit louder, but not much. I have driven manual trans vehicles for 35 years & I have never heard such a sound as this before. Admittedly, this is my first truck with the Duramax &
6sp, but I am suspicious.I'd appreciate your opinions. I am considering taking the truck back to the dealer to ask that it be looked at again. Perhaps a different dealer for a 2nd opinion?
Dave