Da#*! Those look an awful lot like the bits I just shook out of my expansion reservoir when I was putting my 98 328i back together (reference timing chain cover replacement thread). After reading this post I got curious because my low coolant light comes on quite often. Besides a lot of sediment I managed to extract a couple of small pieces of curved plastic that look suspiciously like the wall of the internal bleed tubing. Just one more $75 to throw on top of the new parts pile. I suppose I could buy a used one but based on what I am reading, there is no telling how long that would last or if were even sound to start with.
Good tech post. It helped me to avoid reinstalling a bad part that I did not know was bad.
Duke.
