F10/F11 the usual headlight water ingress

[CheresX]

Greetings everyone

The usual water intrusion in one of the headlights occurred in my 2011 535i F11.
I would like to assist a relative who has found a 2011 F10 535i in avoiding this situation, if that is at all feasible.
Is there anything that can be done, apart from covering the car every time it rains? It's obviously not going to happen.

Replace the seals if they have expired?
Put a sealant around the unit's perimeter.

Does anyone know how to stop or at least slow down the water from entering the car, given that this is a common issue with this model?

Much obliged

[BEERMAN]

For my instance, I let the lamps dry completely before cleaning the joint between the lens and black body thoroughly to remove any debris. Then, I applied a bead of clear RTV around the joint to seal it.

[BEERMAN]

Sinoparcel D4S Xenon Bulb, 8000K Ice Blue, 35W, Pack of 2 | Distinctive Appearance, OEM HID Headlight Replacement, MOT Compliant, Compatible with 66440 42402, P32d-5 : Amazon.co.uk: Automotive

[BEERMAN]

https://www.amazon.co.uk/s/?search-alias=aps&field-keywords=RTV

[CheresX]

Thanks, there isn't a tonne of water in the units just yet. Nothing at all, not even warning lights.
It seems like this RTV around the joint could be a good preventative measure to try.
Would you mind telling me what RTV is and which joint it is?!? Can you tell me how much effort is required to simply gain access to this joint?
Pardon me, but I'm not very well-versed in this area.
At the time (about February 2026), I took it to a shop in the Midlands, and they repaired it for approximately one-third of what BMW had quoted (£3,000 for a single headlight).
I appreciate it once more.

[BEERMAN]

Looking at the joint between the lamp's body and clear lens, you can see that RTV is a silicone sealer. Blurred line connecting black and clear.

It's not a big deal to remove the front bumper in order to access the lamps on f10/11.

[CheresX]

I am very grateful for this.

[Geek2232]

I've always assumed it's the inner arch liners. Those gaps get hit with spray from the rain with a lot of force when you're going fast. Also, check under the bonnet for the lamps. I had an F31 with a hairline crack, so water would pool and seep in. I had an MG ZT with a lost small panel in the arch liner, so there was light moisture. That's why I think it happens to BMW lights and other brands. I sealed the gaps between the arch liners on my F31 with silicone, and it's easy to remove if the insp

[Geek2232]

Sinoparcel D4S Xenon Bulb, 8000K Ice Blue, 35W, Pack of 2 | Distinctive Appearance, OEM HID Headlight Replacement, MOT Compliant, Compatible with 66440 42402, P32d-5 : Amazon.co.uk: Automotive

[Geek2232]

Amazon.co.uk : BMW

[CheresX]

Thank you, I will remember this.