I have noticed that when I start my '01 CTD up it is much quieter when it is cold than warm. Almost as quiet as new engines in the '03's. As the engine warms up, the the familiar rattle comes in.

Anyone have an explanation for this phenomenon?

 

No I don't, but mine does the same thing. As I back it out of the garage it seems to get louder. I have an 02 and use shell rotella oil.
Waam Holland, Mich.

 

hmmm...mine is LOUD when it's real cold out when first started..it quiets a little when warmed up..