As the engine warms up, the pitch and decibels of the clatter subsides to a normal muted clatter (as in summer). If it's very cold out (-40) this clatter may be just as prominent as when the engine is first started. Yes, it DOES take longer to get to normal operating temperature as well.
In fact, if an engine is at normal operating temperature, and you stop for a few minutes and leave the engine running, the temperature will DECREASE.. ie. the engine will cool off, and your heater output decreases
Diesels require load to generate heat... idling does NOT warm up a diesel engine!
If a diesel is misfiring when first started when the engine is cold, let the idle smooth out first before driving.. typically a few seconds to a minute.
Now, the TDI has heaters here there and everywhere to help minimize the problems I've just described... I didn't know that until I joined this forum
I've had diesels in -40 weather (1982 Toyota LandCruiser with 3.4 litre diesel), and this engine would start right away with a block heater and battery blankets, but would smoke and misfire for the first few seconds running on number 1 diesel (winter blend).
There is typically a 1 or 2 mpg difference with winter blend fuel... and a trail of blue smoke from the exhaust. I experienced this up in Hinton, Alberta where I lived for a while... brrr! Not too sure if modern chemistry and engineering has changed the formulation of number 1 diesel since those days or not.
Hope this helps,
Harry.
------------------
'87 Golf Diesel (267000+ Km)
'00 Golf TDI GLS (1000 + Km)