Diesel Newbie...Is this normal???

[troy73]

I recently purchased a 2008 F350 (100,000 miles) and while I just love the truck I have never owned a diesel and am questioning some noises. Any help would be much appreciated.

When cold and at RPM's of 1800-2700 sounds like gas motor detonation. Under heavy throttle the noise is non existent. Is this normal?? If so, is there ever a problem with such a noise (diesel knock??)....How do I know when it is a major issue and not something normal??

Also, while in active regen the motor takes on a totally different sound with absolutely NO knock just sounds like a smooth running gas motor....Is that normal as well??

Sorry so long winded, thanks for any help...