failure proofing fog lights?

[Sidewaze Samm]

The foglights on my facelift zed are in a pretty bad way. A previous owner has drilled holes to try and deal with the condensation, but the lights are not clever at all. Just got a nice new set of facelift foglights to replace the existing ones and was thinking about ways to extend their life.

Is it known why these light units fail? I'm guessing it may be moisture ingress at the join between the lens and the housing, and if so whether applying some kind of sealant to the join would help prevent this.

Anyone any ideas, suggestions of best sealant or tried anything else before?

 

[firebobby]

Strange really, the early Zed fogs don't suffer like this..thank god

 

[Mr Tidy]

It's one of life's mysteries!

Mine were pretty good when I got the car, but started to shows signs of damp inside them - so I drilled a few holes in the bottom of the lenses. Maybe I ought to use them occasionally to help keep them dry?

Anyway OP if you do find out I'd love to know the answer!

 

[Zedtastic]

Mine were also in a very sorry state. I replaced them with shiny new ones 3 months ago, and used silicone sealant around the bulb seal. I had hoped this would keep them fresh looking for a long time, but recently noticed one of them has already started to steam up. If theres a good solution to this I'd like to know too.

 

[Smartbear]

Mine were also in a very sorry state. I replaced them with shiny new ones 3 months ago, and used silicone sealant around the bulb seal. I had hoped this would keep them fresh looking for a long time, but recently noticed one of them has already started to steam up. If theres a good solution to this I'd like to know too.

I think drilling ventilation holes before the lights are ruined maybe more useful, it’s normally carried out too late
Rob

 

[biojo]

its a poor design, there chromed on outside which eventully srtarts falling off then water seeps through.

new sets about 115 quid when theres discount on carparts4less, changed mine last weekend

 

[Sidewaze Samm]

I think drilling ventilation holes before the lights are ruined maybe more useful, it’s normally carried out too late

Could well be right. Just difficult to bring myself to do it to units that are so new, so shiny and so expensive! And although I'm pretty sure it would stop condensation forming, I'm not so sure it wouldn't just allow water ingress and subsequent corrosion. Maybe using really small 2mm holes would help? But then if water was forced in by driving at speed, the holes would be too small to allow it to get out easily (because of surface tension or whatever), resulting in errr... condensation
I guess one question is - when driving is the underside of the foglight in a low pressure zone or high pressure? I guess high pressure, which is a shame as low pressure could effectively suck moisture out of the holes.

 

[Jl-c]

On my old 911, the rear lights used to suffer from condensation issues. I fed a tube from the blower motor into each light unit which provided positive pressure air slightly heated into each one. They then vented from the designed vents (as the BMW fogs have at the top of them) No issues after that. Maybe something similar?