Sunroof drain or Windscreen seal?

[Tinkley]

Update - Leak to fusebox fixed, 2 layers 200gm glass and 2 layers 6k carbon plain weave. Ground out all the rust visible and worst was holes through the 2 bits either side of the 'valley' and up to inner wing. Inner wing was a bit pitted but passable after grinding. A pillar fine just needs paint towards that end. Likewise vertical rear side to strut mount, so all the structural bits are basically OK.

The wheel arch will require ahem 'light repair' ie chop a few bits out and fill'em with the roving, cut back till flush with steel and paint. Will also let me fill with microfibres and balloons the cavity behind the front strut vertical and the underside of inner wing. Interestingly I found a very good american youtube video of a guy doing a hybrid repair. All the rotten steel was cleaned, cut out and he welded in a new panel. Then he built up the inner rear wheel arch with roving and structural epoxy. Like him I am using the West system epoxy. If anyone wants the link here it is

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Thanks for the tips on 'digging' in under bits that seemed sound, it was worth getting to the edges and seeing how far it had gone. BTW for the MOT they will never check under the washer bottle because you can't see it easily 300mm from suspension mount pah!

[rutter123]

yes unfortunately the underseal is a pretty good moisture trap as i found out too, read n/s/r chassis rail on my tzdt looked in good shape but gave it a poke and it all fell off, oh dear, with the rust extending up into the rear axle mounting area and eaten well into the n/s sill which also looked in better shape than it actually was.

[Tinkley]

Thanks Rutter, without your tip 'carry on digging' I might have left a lot more rot!. Least the battery won't go flat when it rains now no more looking like a Halloween ghost...

I am reasonably au fait with the front half of the car, I've spent some time under it now.. and know what needs doing. The back half is next, preferably before winter, so it doesn't get to the throw it away point. One door n/s/r has paint holding the bottom flat together... but that's fixable or swappable. More worried about rear subframe and mounts especially after seeing that shot of Jaba's car.

Must be that the water gets in either chips or under the grommets and once the corrosion starts it spreads under the paint like a rash. Also whatever that 'sealant' is it seems to go porous or even starts a chemical reaction releasing oxygen onto the steel. Maybe it just shrinks slightly away from the edges and allows water to sit there.

Hopefully when the new sills are welded in, the boys can sort any other issues at the rear without major drama. They have at least had a good look before quoting..not cheap (could buy 1 or 2 other poor BX for money) but sometimes better the devil ... and lots of bits are still good on this car.