n42/n46 valve stem seals

[Manfred]

Why does BMW E90 valve stem seals in general wear out so quickly?

My car is starting to smoke at 100 000 km's.

 

[AdiS]

Who knows, but the fact is that it happens. Often.

BMW Leo Haese are running a fantastic special on this repair:
http://www.bmwfanatics.co.za/showthread.php?tid=74058

Chat to John, he is always willing to help, even if its advice.

 

[zippy320]

Mine on my E46 went at around 200 000kms I think which is not to bad .. I also wondered if they had a limited lifespan or do they just go out at random .