Putting this here for future reference really.... I've had a wet roof lining where the drivers side sun visor attaches to the roof for the last few weeks after rain.

Suspecting a blocked sunroof drain I blew compressed air down both sides but it still leaked.

I had the plastic roof gutter covers off to clean them out in case water wasn't draining away quickly enough, (they were solid with grime) but it still leaked.

In the end I thought I'd got a hole in the sunroof drain tube, or it was leaking where the plastic tube attaches to the sunroof assembly so today I took the headlining out to check it but it was fine. After loads of poking about and pouring of water from a watering can I found the hole. I've sprung a leak in the silicone bonding that is used to hold the windscreen in!

After taking the upper screen finisher off and squeezing a tube of black silicone in there I seem to be water tight again.

So it's always worth checking the seal there once you've ruled out the sunroof drains. The windscreen was new 5 or 6 years ago, and it's been fine until recently.

Well done that man

Silicone is the work of the devil and should only be used in bathrooms... Tiger Seal is the stuff you want for leaky bits

I drilled about eleventeen holes in the roof of my Mercedes Sprinter to attach flashing beacons, LED light bar and various other bits n'bobs requiring holes drilled. Before I put the bolts in, I dabbed Tiger Bond inside each hole and outside, as well as a slpotch down in the hole Not a drip. Guy who eventually bought it said it was the driest van he'd looked at Mind you, I did fit a roof light opening hatch with built in ventilation which helped a lot....

But as far as I know, it's still a drip free zone