SITUATION: When starting a cold engine, a “plume of blue smoke” can be seen emitting from the exhaust tailpipe for approximately 10-20 seconds. There is no engine malfunction light illuminated (no turbocharger boost faults are stored) and no drivability issues are detected.
CAUSE: When the vehicle is parked overnight the engine oil pressure will equalize, this may cause engine oil to leak past the turbocharger “exhaust side” turbine seal due to carbonization of the turbocharger sealing ring.
CORRECTION: If “affected vehicle” is experiencing the “situation” noted above, replace the “engine oil feed line” to the turbocharger using part number 11 42 8 648 368* or 11 42 8 678 840. The “new” engine oil feed line part numbers listed above incorporates a “check valve” on the engine side of the engine oil feed line. The check valve eliminates engine oil pressure equalization and the consequential engine oil leakage past the turbocharger’s “exhaust side” turbine seal.