Nissan Repair: smokey engine, fuel filter, bushings

Question
Hi Von, i replaced all the filters as requested and this has cured the misfire, although the tickover seems a little slow on starting from cold, but is fine when engine is warm. When i replaced the fuel filter it seemed to me as though it smelt of paraffin, the engine is now running sweet after putting additive in the diesel, but the problem i am having is that the engine is blowing black smoke from the exhaust when put into drive, if i am at standstill with the car in park and accelerate gently i don't get any smoke, it also seems to be down on power for a turbo, although i can hear the turbo whizzing, can you help me please?
Kind Regards and Best Wishes Clive.

Answer
Clive,

The turbo is probably blown.  That is, the seals are blown and the oil that is used to lubricate the bushings is leaking past the seals.  You can confirm this by removing the exhaust past the turbo and inspect for signs of oil.  If there is oil the turbo needs to be replaced.  Otherwise, the rings are going and that could cause the smoke too.  But, if the power is down that leads me to think the bushings are worn and the turbo is tilting ever so slightly and that is causing it to drag on the housing.  That kills the power.