Knocking
I had an '02 Duramax that did the same thing. This was an issue that was brought up to Chevy and they said it was some kind of benign thing with trapped gasses I think. (sounds like crap to me) It ususally happened more when the truck was cold and it led me to think it was just oil that didn't get into the heads right away casing the clattering. it was ususally on one side. All other systems were ok on this truck. I ran a chip on it too but I heard from others who had this problem w/o running a chip.
I had an '02 Duramax that did the same thing. This was an issue that was brought up to Chevy and they said it was some kind of benign thing with trapped gasses I think. (sounds like crap to me) It ususally happened more when the truck was cold and it led me to think it was just oil that didn't get into the heads right away casing the clattering. it was ususally on one side. All other systems were ok on this truck. I ran a chip on it too but I heard from others who had this problem w/o running a chip.