another could be the diesel you,re using,,,,,are you by any chance using supermarket diesel....my mate used it and was getting loads of white smoke and thought his head gasket was leaking but mechanic told him it was thecheap diesel he,d been getting from supermarket.a couple of weeks later after a fuel filter change all smoke had gone,,,,,,,,,,by the way this also happens when using supermarket high octane of 97 oct or 101oct ,,,same solution