Mercedes-Benz W163 ML270 starting issues, smoke, soot, etc

It all starts one morning when, well, it won't start. So begins the tale of how I addressed this one. Issue #1: air in the fuel lines. The main offenders are the O rings on the clear lines running between the filter, lift pump, rail and high pressure pump returns. There are also some bush-repair and emergency bits added, for the next time it catches me out, in the middle of nowhere. The first issue motivates you to chase the rest of the common issues on this engine (and most modern diesel engines). I have decided there is a proper order to do these things in and there is also the order which let's you get away with the least work for practical returns. This one is now leak free, smoke free and soot free. But it still has gremlins, lurking under, specifically, the intake manifold. Those are for another day.