I make a point of reading up on known issues and doing preemptive maintenance where possible. So I’m aware of the tank guard and have lanoguarded mine but this one had passed me by until I saw this.
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Maybe it’s because the opening roof is less common on the 494 that I’d not spotted it.

Anyway, I’m going to look at epoxying in some 10mm stainless inserts which sound like a cheap and simple way of avoiding the problem in the first place.
One question is, nobody mentions the front drains. Do they not suffer? 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

l494 only got back drains
well that's all i could find on mine
passenger side was blocked with leaves and stuff but looked good after i cleaned it out.
got a little bottle brush down it,couple of coats of rust eater then treated it with stone chip
all good  2014 L494 5.0 SC
2014 L538 2.2 SD4

Sounds like a plan. Not sure whether to simply paint it or do the stainless insert trick - tempted with the latter as it's quick, cheap and should leave no room for doubt, but as you say, testing and clearing the drains is equally important.
Haven't looked at mine yet. Got a cheap amazon endescope camera coming for my iphone to make it a little easier to see. 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

Once the mouldings or finishers either side of the sunroof are removed you should have complete access to the roof ditch and be able to see all.

I do wonder if they are reusable and go back on with no problems? As long as the clips that hold it in place don't fail I see no reason why not.

How did they go back on for you Ironhorse?

+1 on that question.
From what I can see, there are 2 trims side by side.
The first outer one is what you remove to fit roof rails - there's a powerful-uk video showing pulling those off but the inner one for the sunroof, I can't find a single thing on. Some show it already removed but how you do that I have no idea. Does it just pull up like the other one or are there bolts? 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

I removed the outer trims so I could fit the roof rails which are now in place. The fitting of the roof rails went well but I did have new finishers to fit into place so that was not a problem.

Looking at the original finishers I removed for the roof rails left me wondering if I could have just put them back into position as was? I doubt it as there are adhesive spacers and other adhesive strips that were no longer usable. In other words the original trim pieces would not have refitted without additional parts ensuring the fit was as intended.

So, I am reluctant to remove the two sunroof trims in case I cannot refit them as is without getting the parts required to do that.

I've been out to have a proper look at mine.
There's no visibility at all, with just the roof open and looking at the trims, I'm not convinced I'd want to mess with the one that covers the drain unless someone can show me a video on removing it.

I bought one of those cheap endoscope cameras that connects to your phone from Amazon - bloody thing didn't work most of the time (it's going back) but in the short moment I got a picture out of it, I managed to catch a glimpse of the drain and .. there's signs of rust. Not much yet, but enough to tell me it's going to be a problem at some point if I don't do something about it.

For access - it's either the trim or else remove the sliding glass panel. Problem is, I can find no info on how to do either. Nothing on youtube and nothing on google.
Does anyone have a workshop manual that covers this?

Update:
L405 but the same thing. Looks like you just have to be brave.
&t=94s 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

They just pull off quite easily
bit of a loud snap sound but all OK
Start from the front with boot open,
Just snap back into place when finished, there are 2 rubber pads where the sticky stuff is left on the roof I just put some silicone on them and not had a issue since 2014 L494 5.0 SC
2014 L538 2.2 SD4

Thanks. Much appreciated.

I’ll try to write a full how-to when I do it. 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

https://www.rangerovers.net/threads/have-y...st-2393113 2026 P460e Autobiography on order

2022 HSE Dynamic P400e

2017 Discovery 3.0 HSE Silicon Silver Nimbus interior and a few extra toys SOLD

2013 HSE Black, Orkney Grey, Ebony Seats and Ivory Interior SOLD

2006 HSE

Plus a few other cars inbetween!

Thanks Jim - Was gonna post this up earlier - Ive done my own range rover and 3 others now so if anyone needs a hand or advice with this issue drop us a message.

Easy fix - You dont need to take the full headliner down you can take the inner weather strip out and unscrew the passenger ceiling light then pull the headliner down and get your hands into wear the drain connects to the rubber drain tube.

You can buy some copper fittings now also ;

https://www.aliexpress.com/p/tesla-landing...nkQAvD_BwE

Or check BQ for a similar fitting.

There's some brilliant ways for fixing it. Those brass fittings would be my first choice if I had a snapped drain.
The focus of my post is slightly different though.
Fixing once it's gone is likely to be a headache, especially given the potential to destroy the amplifiers.

This forum must be full of people with affected cars, like mine, that simply haven't failed yet. It's them I'm really hoping to target.

My last car was a Jag XF. That has a problem where the rear crash bar rots out and dumps the exhaust on the floor. I sort-of knew about it, but didn't worry myself until one day i came out to find my exhaust on the floor. What followed was 2 months of hassle and considerable expense.
Point is, had I just thought about it for a minute, I could have spent a couple of hours removing my, at the time, slightly rusty but sound crash bar, rub it down, drown it in hammerite and pop it back. Problem solved. No 2 months finding a replacement and no £400 bill.

So it is with the drains. There's some clever people like you guys that sound to have fixing it down to a T but truth is, (and correct me if you disagree) epoxying an insert into the not-yet-rotted-out pipe, should mean that the problem stops getting any worse, the pipe never snaps and you never have to bail out your amplifier and dry out the carpet.

I want to get that message out to all the people with 494s (and 405s)who have sunroofs that for an hour of effort and less than £10 can avoid the whole nightmare in the first place.
To be fair, it's a service all good specialists should offer! 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

I assume these inserts are suitable and they look to be longer, thus giving more support, than the plastic ones?

https://www.screwfix.com/p/hep2o-smartslee...pack/6398f MY17 RRS 4.4d V8 Autobiography - Aintree Green (also referred to on Topix as British Racing Green)

I think so.
I bought some similar ones from eBay. My only hesitation on those is the shape of the head which I’m not sure will be so easy to seal but I imagine I’m overthinking it. 2021 L494 D300MHEV Autobiography
2019 Discovery Sport D180 HSE

@ironhorse when you say 2 rear drains do you mean those over each B Pillar please?