2004 2500 Cummins, NV5600 transmission 2wd, clutch kit replaced at 140 k, noticed a higher noise level. Noise sounds like a second diesel running under the truck with the clutch engaged in neutral. Disengaged noise goes away.

pat

 

Do you hear it in every gear?

 

Yes higher noise levels when tranny is under load, 55 press in clutch noise level drops to nil. Mechanic thinks it’s the input shaft carrier bearing.
for those that posted throw out bearing, the throw out bearing only comes into play when the clutch is disengaged, and the noise goes away.
i think the tell is in neutral engine at idle clutch engaged distinctive noise. In any case the 16th it's getting pulled down.

 

The external slave cylinder has the throw out bearing constantly riding on the pressure plate, so maybe when you depress the clutch it puts pressure on the bearing and it goes silent, but could also be the input shaft bearing. Only way to know is to pop the slave off, and pull the clutch fork back away from the pressure plate if noise goes away it's the throw out bearing.