Leaky car

[jazzygm]

My valver is leaking 
The water appears to be coming from behind the dash, so far its already corroded the floorpan and rotted the sound deadening (carpets now removed, new sound deadening sourced, welding waiting to happen!) But I still haven't found the source of the problem.  Matey-matey mentions that the bulkhead seals and the plastic leaf mesh on the scuttle.  Does anyone know how difficult these seals are to replace? Could it be anything else?
ANY help appreciated!

[Blue MK2]

heater matrix?

everyone goes on about these?

[jazzygm]

Yeah, I did read that the matrix has a tendency to leak, but i know its not! Heater works fine, and it only leaks when it rains, so its definitely water from the outside.

At the side of the scuttle there is a square hole which I presume is the run off for excess water. Where is this supposed to come out, when I poured some water down I could see water seeping out through all around the arch liner etc instead of just from the bottom of the car 

[jazzygm]

bump!

[Gambit]

yes it runs in behind the plastic arch liner

your's is probably coming in round the heater motor surround. take it out and reseal it

[rubjonny]

Common leaks:
Bonnet release cable grommet under scuttle tray - tons of grease on it sorts the problem
Blower fan box under scuttle tray - tons of grease on the seal sorts the problem
Blocked drain channels under scuttle tray - clear all the crap out the scuttle tray
Plastic membranes behind door cards torn - replace with plastic sheeting and fix in place with waterproof ducktape
Grommets missing in bulkhead/floorpan - replace grommets
Door seals letting in water - replace

[KENTHFC]

Go onto matey matey and look there. I ve just been on there, loads of places where mk II s leak. bound to have your leak there.