Hi Chris,

I had something similar happen to me 3 minutes out of the PO's driveway after
I bought my first Vanagon. The vehicle must have seen a lot of overheating
and this t-pipe (as VW refers to it) had gotten brittle from all that baking
heat and fractured.
Water, water everywhere. I caved in and paid $53 for the part (That turned
out to be $10 cheaper than what other dealers in the area wanted). Anyway,
two hours or so of wrenching down there, finally got the part replaced. Yes,
I did find that little plug that you're talking about. It appears to be
plastic welded in place. Tried to pry it out, out of curiosity and this thing
was ... well, stuck in there. Even after breaking the part to pieces, the
plug remained attached to the broken parts. That leads me to believe that it
is not likely to fail unless the entire t-pipe fails. The pressure cooker of
an overheating wasserboxer will make plastic parts just a little messy.

Ben