As far as I know, pretty much all Vantages and DB9/DBSs suffer from fogging headlights. I know it's a common problem and my car is affected by it as well.

Here's the service bulletin for addressing it, scroll down and you'll see it:
http://www.pistonheads.com/gassing/topic.asp?t=1114410

Cliff notes: Drill a hole, dry up the moisture, and stick some silica gel packs in there to absorb moisture.

I'm just going to go ahead and say it... this is one of the most ghetto solutions I've ever heard of to fix something from a manufacturer.

I'm getting ready to tear apart the headlights on my 4Runner. I'll be painting the housings (going from chrome to flat metallic grey), upgrading the projector lenses, and adding angel eyes just for fun. While getting ready, I came across something I haven't seen before: Goretex patches designed to vent moisture without allowing more back in.

I found them on the website of The Retrofit Source, in the "Accessories" section. They're $4 per pair of patches, one for each headlight - pretty cheap if they work!

I'm going to order a handful of them when I place my order for my 4Runner stuff. The main thing I'm wondering is if anyone knows for sure whether or not our headlights are fully sealed. It won't do any good to stick a Goretex patch on there if there are more holes allowing moisture back in!

 

Wow, good project you're taking on. Make sure you make a build-threat of it; surely interested since I'd like to get rid of that problem too.

Re the GoreTex patches: I guess its a matter of guinea-pigging....

 

I figure it's a cheap enough experiment. I've undertaken things on this car that were far more costly to try out than a $4 pair of patches lol

I'm going to approach it like the service bulletin suggests but instead of using silica gel packs, I'll be drilling a small hole in where it suggests the packs be placed (I'm assuming that the hole would be out of sight there, given that the silica gel packs would not be positioned in a way that they would be visible). The hole is going to be small, ~10mm, and then covered back up with the patch.

Regarding my sanity for drilling a hole in a $1600+ headlight:
The factory recommended procedure for getting moisture/water out of the tail lights is to drill a hole at the bottom of the housing so water can drain out. At least I'll be doing it on the side and re-sealing it with a breathable patch so moisture can escape when it is evaporated by the heat from the headlights.

I'll only do one headlight at first so I can compare the two over time - I'll keep an eye on them whenever I drive, but now that winter is approaching, observation might take a little longer than it should for something as simple as this. I placed my order yesterday and they shipped today so I should have them soon. I'll modify one of the headlights as soon as they come in and begin testing next week.

 

... too much eggnog?

 

No such thing as too much eggnog

 

Would 'breather lines' not just work? Audi-parts can be bought seperately http://www.ecstuning.com/Audi-B8_S4-...224/ES2571658/ and although they're not as competitive priced as the GoreTex patches, they're surely a proven solution.

Just a thought..

 

It looks like the headlight has a fitting molded into the back of the housing for that breather hose to connect to. If I'm understanding its design correctly, I'd not only have to drill a hole, I'd also have to find a way to secure the connector and find a way to seal between it and the housing.

 

The headlamps are not fully sealed, I assume you would be drilling the hole for your "patch" idea? You can fit the silica packs in the access panel for HID bulb replacement.

 

As mentioned earlier I wanted to get rid of the fogging issue as well. Instead of using a breather line or GoreTex patches I've opted for a slightly different [fully reversible] solution.

I've installed 2" 12V 0.3W PC-style fans at the access point behind the HID-main beam light. This fan sucks air in from outside and therefore creates a positive pressure and air circulation in the headlamp. On the other access point I've installed a blank filter to allow the air to be pushed out. I've covered-off around 60% of that filter opening to allow 'some' over-pressure (preventing dust to come-in despite the filter).

I've bought four (4) 3" drainpipe end pieces which I machined to the desired size: they're a snap-fit on the headlight bezel/protrusion which normally has the rubber covers fitted.

On the electrical side of things: first criteria was these fans to run for sometime even after stopping the car: because that is when I started to see the condensation in particular (switching-off the HID's). Therefore I've used a 60C/140F temperature switch which I've fitted to one of the engine's cooling water pipes.

With the earth-lead 'switched' at around 60C/140F it means that the fan's start running after the car is started and the cooling water is warm. Once the engine is switched-off, the 0.3W fans continue running until the engine coolant temperature decreases below 60C/140F. In my case (in an average 29C/84F climate) that means around 2,5 hours.

This clears the headlights fully, way before the 2,5 hrs period. I've been thinking to change the switch to 80C/176F or 90C/194F instead (= shorter running of fans) but since they're only 0.3W I can't be bothered.

Pictures:

 

Very clever. Do the fans make noise after the car is off? It looks like there is one chamber behind the two openings. I would think that most of the air flow will take the path of least resistance and pass back out the other opening rather than circulate around in the headlight. I guess the over pressure will keep any air from coming in in other areas.

This makes me wonder if the problem is that when the headlights are on they heat the air and force it out. then when you turn off the head lights, they cool and create a vacuum thus pulling in outside, moist air. Which would then fog the next time you turn on the headlights.

 

Here are copies of a couple of Service Bulletins about having tears in your eyes.

 

The fans aren't making noise at all, even with the car switched-off.

You are correct, there is just one chamber behind both openings. I initially did not tape-off the center of the filter which didn't showed the result which I'm now seeing, letting me guess that 'the road of less resistance' was thru the filter indeed. I've tried to cover off the 'filter' opening with the OEM rubber but the fans rpm reduced a lot, showing an opening to allow flow is required.

Ideally, somewhere at the front-bottom of the headlight (around the blinker light opening) should be the opening but given the results i'm seeing I'm not drilling a hole there.

I guess a combination of 'immediate' flow just after the car has started also enable's cooling to the HID, overall reducing the Delta-T between internal/external which obviously also has a positive effect.

 

Really ingenious! Regarding the flow of air I would think it would travel in one direction until it meets resistance and then moves about until it finds an exit. So my guess it would cover most of the lens interior. I'm not an fluid dynamics guy of any sort so that's just a guess. Maybe an issue would be dust over time.

 

I will have to monitor indeed how the headlamps withstand dust over time, despite the fine-filters I got fitted. I guess a 'faster' result/dry-up will take place if holes are drilled at the front section of the housing but I'm more then happy with the current result.

 

Hi sdekoning,

I have read your info on the headlight fan/vent system, brilliant solution. I was just wondering if the filters worked with regards to the dust and if they did, what kind of filter material was it ? Cheers.