I had a similar issue as m5james. My 2000 4.4 with 120k had the plastic (plastic! PLASTIC!!!) chain guides go, which took 35 hours of labor (at $100 per) to fix. Add the "as long as it's torn apart" stuff like tensioners, waterpump, etc., it was $5,500 to fix. Ouch. Has tainted my view of BMW's, maybe forever.

Now I have the infamous Vanos noise. Yes, I have 140k on her, but for the money and the reputation, these should be typical German 300k cars. Now I am waiting for the tranny to go. Thinking about pulling the ripcord...