Mk3 NC - Rear Drain Holes, Pipes and the flaps!
As I was dismantling the rear chassis like you do… I came across the often mentioned drain holes and the one way flaps.
As most people will never get to this level of dismantling I thought it possibly helpful to show you what is being talked about rather than trying to visualise this benign object.
There are two pipes that direct water from the inside of the rear hood area out through the chassis rail through two one way valves and reputedly prevent road noise interfering with driving bliss.
What I did not realise is there are two flap valves.
I hope the pictures shows you what you will probably never see for yourselves.
If anyone wants a spare I have two, replaced by removing the seat belt and the plastic box behind it, to gain access to the inside of the rear chassis chamber and the pipe running through the middle.
I was surprised how much solid detritus came out when I shook it and further how tight they seal when snapped shut.
Rodding in the wrong direction would certainly damage the flaps, now you can see why.