Just put the bottom hose back on the 159 and noticed that there appears to be what looks like soot in the bottom drivers sied of the aircon heat exchanger and the radiator - I know the intercooler sits between these, so, what are the chances that the intercooler has popped ? Directly behind the rad is the turbo hose that I mentioned had loads of soot/grime/oil all over it (which I cleaned off to check the hose for splits).
I put everything back together today and started it - started ok, let it tick over for 10-15 seconds, blipped the throttle and revs bearly changed - pressed the throttle pedal a little slower and and the revs built up slowly. The more I did this the better it seemed to get, but, after doing it 7 or 8 times it started chucking white smoke out the back (not lots like a blown turbo, but, enough to be visible in the rear view mirror) and started to get a bit 'lumpy'. Revved it a couple more times and each time it got more lumpy and more smokey - turned it off for fear of doing any damage ! This whole process took 60-90 seconds, the temperature gauge never moved off the bottom, and the boost gauge showed no more than 1/4 boost at any time.
Took the cambelt cover off - belt looks ok, no obvious missing teeth, teeth look to have a good edge, tension good, no obvious signs of slippage.
I am now completely baffled !