Originally Posted by Alastair

Nah, Injection timing retarded due to general wear and tear of chain and sprockets, especially if it hasn't been checked/re-set before....

Check chain-stretch, and re-set I.P timing.....

It just could be very close valve-clearances....Had that recently on a 300D I recently aquired. It would only run on 4 pots until warm, then all 5....(Valve clearances are set up to increase just slightly on the 615-617 engines as they get hot, by up to 2-3 thou....Ally cam-bearing towers expand more than the steel of the valves/followers etc...)

Blue/white smoke is unburned fuel and a cold engine will be much more prone to mis-fire when the timing is not right....

Chains are generally good for around 300K they say......

Cheaper than a whole top-end re-build, (If it should break!) and reasonably easy to change--If you are worried, roll in a new chain, and check pump timing after.......