[kk2002s]

That overflow tube basically drains the cavity above the expansion tank. There is a hole between the Bleeder value and the Fill. So any excess that comes up out of either Cap or Bleeder can drain out that hole, down the tube just in front of the right rear tire.
Are you getting any condensation on the trunk lid above the expansion tank??

I have used sandwich bags over the fill cap and Bleeder to try and isolate which one was causing condensation for me.
For me it was the Bleeder and I was able to replace just the (2) 'O' rings and that solved it.

I was getting enough condensation that when everything cooled, I would see a few drops worth from the overflow on the floor