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
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?