e39 hard starting (flooding) and black smoke, what to check?

[genphreak]

A friend is going to bring around their mint condition e39. I told them I know nothing about e39s but they are coming anyway, perhaps they want to stress me out (Any job that take >3 beers can do that, but I hear e39s sometimes need a garage-based mini Oktoberfest to fix seemingly simple things).

The car has been looked after but only ever done short trips but has had oil changes every 6 months religiously, not sure what else.

Apparently it is having trouble starting- more often than it used to.

Does anyone know what to check? They told me the battery is not very old and I did notice last time the oil cap was a medium to dark-tan colour underneath. It's a 04/97 built e39 euro 523i (M52B25TU) that has only done 82,000km. For a 16 year old car, that's a lot of short trips...

i.e. It isn't the older one;
it is this one:




Symptoms:
Flooding on occasion when starting; always happens when re-started after running for less than a two minutes. Has to be started the 'Italian way' (Wide Open Throttle) which results in a bellowing of black smoke all over the place once it fires up.

- does the CCV cause trouble on the later engines?
- perhaps a blocked dipstick return pipe is possible?

I was thinking it might be worth checking the
0. Coolant for oil, oil for coolant
1. Cam Position sensor
2. O2 sensor
3. engine temp sensor
these no doubt need to be done as preventative maintenance, but I figure to just check them first to find the root cause.

Thanks in advance for any other ideas/suggestions on other things it could be...