yesterday i brought an a4 avant 3.0 v6 tdi 2005 auto (privately) drives sweet as a nut imo sounds fine but when ticking over when warm it develops a smoking from the exhaust which is white/bluey colour a when you drive it away it seems to clear mechanic says its injectors or rocker cover something and a mate of mine who used to work for audi said engine sounds like timing belt needs replacing i feel sick as a dog and feel like having a good old cry!!