Wow rwalker, your first 4 posts are informative ones, including an emergency patch that any of us with the V8 X5 can use when the plastic hose around the expansion tank breaks. (which I mainly see when someone accidentally rests their hand on it/leans on it on accident)
And I wouldn't lose sleep over the plastic bits from the cap... what you see with your cap is perhaps the most common failure of the radiator cap, and I've never seen a problem caused by the tiny bits of plastic. (my guess is they end up in the bottom of the radiator end tanks) But you will want to get a new cap asap as the seals being in place are important for proper cooling system operation. And when it's all done, maybe treat her to a cooling system flush. She likes that about every 3-4 years or so. .
