Diesel Turbo GT1749V for Audi A3 VW 1.9 Tdi Golf 115HP Auy Ajm Turbocharger

  
You were grinding or carrying near the engine with the turbo removed. You blocked the turbo oil drain pipe with a piece of tape. You forget to take the piece of tape off and install the turbo. Start it up and instantly smoke like James Bond. The oil flow in the turbo has nowhere to go and is pumped through the bearing seals. If your turbo does this, check that the oil drain is not blocked, remove it and restart it. The turbo will be fine, it will take a few minutes of driving to burn off all the oil from the exhaust system. Additionally, a blocked crankcase vent will result in excessive pressure buildup in the crankcase. This prevents oil from flowing from the turbo and blows excess oil through the seals.