Hello,
Just fixed a weird list of random electric gremlins by replacing the bulb holders/circuit boards and connectors in the rear light clusters of my Mk7 Transit, a load of corrosion issues in there. The right side in particular had water in it, not in the lens bit, but in the space inside the bodywork where the wires live and which the lens bit pushes into.
So, to stop it happening again I need to seal it to keep the water out.
Googling has not yielded any form of rubber seal or gasket for this van so I’m thinking maybe some silicon sealant stuff. Any recomendations? I obviously need it to be watertight and withstand vibrations and other things but I don’t want it to be an adhesive of any sort as I’ll need to remove these again to change bulbs and things.
What do you guys use?
Thanks

Caraflex type stuff (the stuff they use for campervans that does not fully set)

https://www.caravantech-shop.co.uk/products/consumables/mastic-n-sealants-maintenance/carafax-caraseal-idl99#.X-ittDRxe70

Some sort of adhesive backed neoprene strip maybe – stuck in place on the bodywork and providing a flexible seal for the lens

However worth thinking about whether problem is moisture getting in, or being unable to get out – is there anything about the way the interior of the van has been lined / panelled that is stopping moisture escaping from that enclosure? Sealing the lens might make things worse rather than better.

Better to drill a drain hole?

Thanks guys.
It’s has been pannelled and lined but this isn’t the problem. The space where the lights go is open below, I was treating the surface rust on the metal in there today and the rust treatment was coming out the bottom of the van OK so there is air circulating in there. The problem appears to be water getting in the top of the lights and running down the wires to the connectors/circiut boards, I would be quite happy sealing around the lights. It’s not pooling in there, it’s just wet.
It is clean water and is definitely coming from the top, it’s not road water being sprayed up from the bottom. And it’s far worse on the right so if it was that I’d expect it both sides.
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How easy is it to remove the stuff you suggest Mark?
It says

SPECIFICATIONS

Non drying bedding sealant
Constant adhesion and flexibility

Is it simple to remove to do to change a bulb or is a glue which doesn’t go solid but still sticks? Screwing the lens back to the van will compress a seal

Sikaflex

Let it set fully

Refit light you’ll now have a compressable.rubber gasket that won’t stick anything together

Another joyous transit design…..I’d check the roof above isn’t rotten letting the water in in the first place.

I think there should be a rubber foam type gasket to fill the slight gap when the lights in the van.
Have you took the one off the other side to see if there is anything missing?

Sikaflex

I’ve got a tube of that somewhere from when I did the skylight, it’s done a good job there. If it’s still squashy when dry then you may be onto something.
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I think there should be a rubber foam type gasket to fill the slight gap when the lights in the van

I was expecting that too, that’s what I was orrignally looking on the google to purchase. The right one, where the big problem is, is a replacement lens from a scrappy after I reversed into my neighbour’s wall. The left one, which has a little dampness in but nowhere near as much, is original, or a least was there when I got it and doesn’t have one either. I assumed I had just badly fitted the right one and left a gap somehow which may not have been there when it left the factory.

I’m building a campervan at the moment and have used this floor sealing up various holes through the floor. Can be removed as it doesn’t set. Is horrible to work with though, sticks to everything.

https://hodgsonsealants.com/product-range/mastics/seamseal-cv

I used to put a liberal amount of fairy liquid on the paintwork then silicone on the light and bolt it up, just not 100% tight. When the silicone sets give the light that little extra tighten to compress the seal. The fairy liquid stops the silicone sticking to the paintwork but creates a very good reusable flexible seal.

Put a thin silicon bead on the light rim. Smooth it flat using your preferred method. Let it dry then put the light back in with the original seal in place.