can someone help me out with this its driving me nuts:

i have a 2007 international with a 500hp cummins isx engine...i have a bad rattle at start up....but...if i push in my clutch pedal in just a little...it stops.....if i start it with the clutch pressed...its quiet...this truck has a brand new clutch, pilot bearing and input shaft bearing installed....if i raise the rpm up to 1000 them let off it will start ratteling again...then stops when i press down on the clutch just a little.....any help?...this truck has 418,000 on it...ive been told that isx has been having problems at this mileage with thrust bushings....anybody????help! :sad:

 

I'm going to guess clutch spring?

Paging Bob H.....