Wow............ this is a very long duration post since March 2019.

I am sharing.........
I use nitrogen injection and maintain that injection, once a month.
Start at post 21

https://mbworld.org/forums/e-class-w...ml#post8991617


FACTS :
My ILS led is fully sealed system.
Me in high humidity country is simply unlucky guy when it comes to condensation inside a sealed container when the air inside it is not dry.

Hope this helps.....

 

so all you did was replace the control module? No need to change headlamp assembly or bulbs? How hard is it to change the module? My drivers side headlamp lights just went out as well.

 

Today I used IR remote termometer to measure internal surface temp of headlight assembly. It was abt 41-43 C, temp of the lens outside of headlight assembly was abt 18 C in lower inner part of headlight up to 22 C on outer upper part. Ambient temp was abt 15 C. The car was driven abt 2 hrs.
I accordance with Dewpoint table the temp of condensation could easily obtained. It was noted by me, that after driving and parking on the place where there is no sunshine(relatively cold and windy parking lots there was condensation, despite there was no rain at all. So how condensation appears. Let say, that temp inside of headlight due to driving and engine heat emission is 20 deg and relatively humidity is 70%, the condensation Will appear if the car hits external air of temp less than 14.3C. If starts raining it means, that relative humidity increases( let assume 90%) and if temp of internal air in headlight is the same (20C), the condensation Will appear at 18,3 C temp of lens.In other words with increasing of relative humidity, the condensation Will appear easier. This is and what actually MB owners face during prain or carwash.
It is clearly obvious, that the only way to mitigate thise















conditions is to reduce the influence of temperature emitted by engine.
I have idea how insulate the headlight housing from heat emission and Will revert with findings after test.

 

Interesting approach. Looking for some answers and solutions. Unluckily my passenger side light just went out after complaining to dealer the last 3 weeks. So now I have a check low beam and spot light inoperable error every time. Very annoying. At least the headlight doesn't look like it's completely out and there is sufficient light still on ground for night time driving.

 

GKH,

You can't isolate heat of engine bay from headlight.
I have tried to do so on the ambient outside air temperature sensor on my bumper, left side lower smaller grille....with thick HVAC insulation foam.
The shielding only delay the heat transfer, but does not eliminate the heat transfer.

Moving car is the only cooling friend our headlight got. In slow creeping traffic jam, there is nothing we can do.

Use Xentry or any decent 3rd party scanner with MB capable software, where you can read actual internal headlight temperature.



The key to prevent fogging is simple in theory, make the air inside your headlight a DRY air to at least 10% humidity, thus I went for the dry nitrogen injection.
Hunting telescope and marine binoculars are nitrogen injected, thus they do not fog.

The drier desiccant pellet as recommended by MB is not too good, because it takes away moisture from the air inside the headlight till itself get saturated.
When saturated it can release powdery dust and so on, when and if you do not replace it in time.

You wrote :
Today I used IR remote termometer to measure internal surface temp of headlight assembly. It was abt 41-43 C, temp of the lens outside of headlight assembly was abt 18 C in lower inner part of headlight up to 22 C on outer upper part. Ambient temp was abt 15 C. The car was driven abt 2 hrs.

RH assumed at 70% for the air inside the headlight internal air space..
Assume the 43C as internal air temperature of headlight . You don't need front lens cooling its internal side to 15C to get lights internal to start its condensation aka dewpoint.
Even at 35C clear lens temperature inside and outside, the headlight will start to fog a bit already.
If your headlight front clear lens only started fogging at 15C of the clear lens outside and inside temperature, the humidity inside the headlight is only 20%.
So from new to now, its a slow build up of moisture into the headlight internal. Just like what happen to my headlight Code 641 ILS LED.



Short of having actual RH% meter inside the headlight, what could happen also is, the cooling effect of your ambient temp of 15C, has managed to cool the INSIDE of the clear lens to 21C.
If so the air humidity inside the headlight is at 30%.



Use this, its much easier : https://www.calculator.net/dew-point-calculator.html


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It so happened today is my maintenance time for the nitrogen injection, as I have done a long trip where 7.2 hours my engine were running non stop, including parking/idling for near 1 hour,
at ambient temp of 32C. I am hoping the internal plastic components of my headlight has given out more moisture into the dry nitrogen.

This is my engine bay temperature for the said 7.2 hours.
Left to right. I was at fuel station filling fuel, close to 5,000 feet altitude of the mountain. Went down the mountain to the sea side, wait till dark for about 1 hour, went back to the mountain up-down and to the highway, to go back home
to my city, Jakarta. Engine was never shut down the entire 7.2 hours, as I need the HVAC always running while waiting , while at ambient temp of 32C being sea level. Coolest on the mountain top was at 19C only.


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This drive on the mountain with snake- roads ( village grade roads ), was so severe and 100's of tight curves, even my curve motor got overheated... LOL


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I got no fogging , ever since I completed the dry nitrogen injection, but......it takes a few nitrogen injections over a period of time. Won't be successful with single injection only.

For my climate, I am at typical 95% humidity in Jakarta day time and 60% night time. Temp is at night 26C as lucky and day time up to 35C, depending on months of the year.
Basically I am living in an oven.

Used to be this way : All I need to do is wash my car, while engine bay still hot/warm, spray lots of water of 27C ambient temp at night to my headlight, and minor fogging will occur.


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This was 3rd time nitrogen injection and it seems I could only bring down the humidity inside the headlight to no better than 20% RH at that time.
Headlight internal temps at its 4 sensors as reported by Xentry , is 55C.to 59C.

The temp of the water I use to spray the headlight till it fogs up is 25C.







I reverse calculate the probable humidity inside the headlight for it to be able to fog at 25-26C / 77 - 79F. I got approx 20% humidity at best, possibly 22% RH.


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The true ILS LED headlight where no bulbs can ever be replaced ......is a sealed unit. Kinda dumb as there is no true way to remove heat from the headlight as there is no vent hole, even though it has a 2 fans inside it.
All the headlight can do is to spread the heat away from the LED array/module into the surrounding air space inside the headlight and hoping decent car speed will cool
the front clear lens and automatically the headlight internal heat get removed too... not efficient but better than nothing.

Since today is the day I need to inject and circulate 3 minutes worth of dry nitrogen to my headlights, I want to share.

01. The headlight is sealed.


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RIGHT SIDE HEADLIGHT. 10 minutes seal integrity test at 3 PSI. Don't exceed 3 PSI. At about 7 PSI or so it will leak air/nitrogen out from its weak seal somewhere on the top part of the light.




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RHD car mine is. The outgoing check-valve has to be removed during nitrogen injection as those check valve opening pressure is quite high at like 7-10 PSI.
I wont allow the headlight body to experience such pressure.




6 minutes seal integrity test.




When pressure test is good, I inject nitrogen for about 3 minutes or about 150 PSI / 10 BAR worth from this 1,800 Liters tank of mine.
150 psi / 10 BAR is about 130 liters of nitrogen in 1 ATM of pressure. So its about I think 13 times the air volume of the headlight.




The next nitrogen injection will be Jan 2025, as per my plan.
I have to keep this maintenance I guess. Only requires 20 minutes per light including seal integrity test if 10 minutes per headlight.

Our headlights are very expensive, S class one probably cost more.
My nitrogen tank and regulator cost only under US$400 for both and I do HVAC DIY with it on my car too, so its even better investment wise.

All you need to do is find the spot to make those holes like I did, to accommodate safely the bulkhead adapter for those hoses.
The white fittings I use is RO ( reverse osmosis water machine ) fittings and not air fitting .

Good luck with your next plan for fog prevention.........

 

Hi. Your post is of course very interesting and it was readed with great focus.
​​​​​But I have some comments:
1. The headlight is not sealed unit. There is Ptfe membrane with air permeability. In other words air mixture circulates without problem(see pictures with blue square). So I personally doubting that after nitrogen incertion, this gas remains there for long time. Do not forget that air mixture is basically abt 72 % N2, so it is may be marginal increasement.
2. We do not need to insulate headlight assembly to extent 100%. We need just to reduce the difference between inside and outside air. These processes are connected by complicated non linear interconnections, so even minor insulation could lead to great improvement.
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Hi. Your post is of course very interesting and it was readed with great focus.
​​​​​But I have some comments:
1. The headlight is Not sealed unit. There is a Ptfe membrane (Your car is W212) with air permeability. In other words air mixture circulates without problem(see pictures with blue square) deppending on differential pressure. So I personally doubting that after nitrogen injection, this gas remains there for long time. Even I think that these headlights do not build internal overpressure. Do not forget that air mixture is basically abt 78% N2, so after injection and if no leakages it is a questonable effect.
2. We do not need to insulate headlight assembly to extent 100%. We need just to reduce the difference between inside and outside air on both sides of the lens. These processes are connected by complicated non linear interconnections, so even minor insulation and subsecuent reduction of internal temp could lead to great improvement. Also internal sensor most probaly measures not air temp inside, but temp of specific component.
3. I have idea how to insulate, and it looks as not expensive at all. So I Will try and Will revert with result.


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Why many other brands, even with headlight by same manufacturer are not so affected by this problem. If we find reason, the problem Will be solved.

 

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You mean this grey membrane ?



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That is not a breathable membrane like Gore-tex.
That I believe is over pressure membrane. Its like silicone when I touch it.

If I can maintain 3 PSI on my headlight , I do not know about yours, mine is sealed.

I said DRY nitrogen, not ambient air nitrogen. We buy/pay for dry nitrogen from a gas supplier. It is super dry, better/drier than 0.1% humidity.
Our air, I know has 78% nitrogen, but overall it is a "wet" air.
In 1,000 liters of air, when at 100% RH, it contains 30.4 cc of water vapor, which is a lot. 1 cc or 1 millimeter of water is about 20 drops of water.






Commercial nitrogen typical spec




I own dive compressor ( I am a diver since 1990 ), a decently big one. We get our breathing air to lower than 0.15% relative humidity or minimum -50C dewpoint and I can do up to -72C dewpoint.
In UK, your firefighter needs their SCBA breathing apparatus to use breathing air ( same as diver ) , to be drier by at least 30 Celsius than coldest ambient air of the location they fight
the fire. If their air supply is not dry, their breathing regulator will freeze from the air moisture in their air supply/tank and they can't breath.
Their air supply if 200 BAR version is brought down to 10 BAR and the pressure reduction at the orifice of the regulator can be as cool as -30C..
Newer SCBA uses 300 BAR tank, that is even more demanding on air dryness. Pressure reduction = COLD.







So, this is why I am so familiar with "fog" or dewpoint. I do underwater video too and if using a GoPro oldie Hero 3 which can be 50C body temperature,
it will fog its plastic dive housing inner lens fast when and if not prepared properly with desiccant or dry air injection. Its the same with our headlight when it is sealed type.

If you want to know if your headlight is sealed or not sealed is easy. Find the round thingy and see if it can be open or not ?
If it can't be opened, your headlight is a sealed unit.

Example :



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Who said other brands of sealed LED headlight does not fog up ?
Google it....... in your tube : use this search word audi BMW Porsche LED headlight condensation


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It is simple physics we are dealing with.
Dry air has much less water moisture ( water in gas form ) in them which can become "liquid" water when the dewpoint is reached.

The hotter the air, the more water moisture/vapor it can carry ( invisible to us ), so what you see by turning ON the headlight hot enough is just a cheapo way of trying to
convert the fog or liquid water back to water moisture/vapor aka water in invisible gas form.
In the end our electronic modules, 2 of them, under the headlight body, will corrode and die from the condensation and then $$$ bye bye.
Bottom of headlight is where water collects, so expected if the module at the bottom get damaged when air is too wet in the headlight and
dewpoint/condensation reached often.

At a mere 65 Celsius, the same 1,000 liters of air can hold water moisture to 161 grams at 100% humidity, compared at 30C at 30 grams.




For fun sake.
161 grams of water per 1,000 liters of air, in a 10 liters container it is 1.61 grams or 30 drops of liquid water we can extract. That is a lot.
/

 

Hi. I Will not argue with anyone. If That membrane is silicon like on Your car, so it is good for You. On my car it is a breatable membrane for sure. If nitrogen injection works I am happy with result, so hope, that Your way works good for You.

 

So as I understood the pressure inside headlight is 3 psi after N2 injection. Did You measure pressure 3 hrs after injection. As I remember I made some tests with Denko Nitto vents with same ptfe membrane and it released pressure relatively slow, let say it has some resistence, but after time the pressure from both sides of membrane stays equal.

 

I pump in nitrogen at 1 ATM pressure only, not any higher. The OUT-going check-valve is removed when I inject nitrogen. So no extra pressure for headlight internal air space.
The sealing integrity test at 3 psi is just to make sure I do not have any leak from plastic crack or something like that.
The electrical connector has a seal and the 2 electronic module has rubber/foam seals too, which can age overtime.

Since I am at sea level which is the highest ATM pressure for where I live, that decent sealing of the headlight should last some months of the dry nitrogen to stay inside the headlight.
Every 2-3 months I will do again nitrogen injection as part of the maintenance. It is simple and fast anyway.

 

Dang.... I did not see this photo yesterday. Must be my internet acting up


This I call a sealed unit.
Nothing you can open up on your headlight, I mean no service door.

 

Sealed unit- Yes, but hermetically sealed- No. What I mean, even in some MB circular letters or TRB it was clearly mentioned, that all headlights are equipped with membrane ensuring temperature and pressure compensation. I had idea to make headlight closed system. In other words to install compensation volume vessel. If we consider phisics Law of Gay-Lussak for ideal gas and its behavior in relation with temp it is possible to calculate volume of that expansion vessel. I made it, but due to dificulties I refused this idea after short period of test . See my previous post regarding this matter. It looks funny, but it Will work 100%,due to fact that the sistem Will be converted to "Hermetically sealed".

 

If you want to make ur headlight a closed system as per ur version, first and foremost you must inject it with dry air ( scuba tank , filled by a very healthy compressor ) or dry nitrogen.
Otherwise the "wet" air inside it will cause condensation.

I have professional dive housing for my DSLR camera, it is a sealed system rated at 100 meters or 11 BAR.
We have vacuum pump fitting for it, one is to make housing seal better by having -14 PSI pressing it while still on land, 2nd is to reduce wet air inside it by sucking out the air out
3rd is to use vacuum pressure sensor as early alarm , when and if vacuum decrease, that means there is a minor leak while underwater.
There is also WET water alarm.

Final say is, get rid of the water vapor in the air inside the headlight..... that is most important.
The headlight decent sealing capability is more than enough to use it as is.

 

While driving in rain yesterday, I got a message to check the right low beam and that the adaptive lighting was not operable. The 3 torch lights and the turn signal work. The LEDs move when I start the car, but don’t light up.

Is it a certainty that I need a new head lamp? Or could it be just the module?

Has anyone had any luck with having a dealership replace the module only? I made some calls and they are recommending the headlamp and module(s). Thank you.

 

Have you called auotobody shops or independant repair shops? Dealership wants to replace everything and charge arm and leg.

 

I just had this happen to me a couple of months ago. My local dealership replaced both headlights with new but charged me to modify them for the dry packs. The headlights replacement and modules were replaced under warranty.

 

That’s great that they were replaced under warranty. Unfortunately, my car is out of warranty. I’m going to see if I can get anywhere with Customer Care.

 

Any luck with this? I too have been driving around with one headlight while trying to figure out where to get this work done without replacing the whole headlight assembly (which they want $4k for parts alone).

 

I called customer care and they advised me to bring it to a dealership to be diagnosed. When I have more details I can call customer care back and ask if they will assist in any way. My appointment with the dealership is next week.

 

On a W222, $2,700 - $3,200 per light to have it replaced (Dealers do not fix these) at the dealer. Be prepared for a very long wait for the replacement part. MB has these fail so often (across all their models) these are chronically on backorder. It's a manufacturer's inadequate design causing this issue. It should be covered by a service bulletin or a recall but MB has decided to stick it to the owners with this problem. Needs to be a class action from owners to remedy this.

 

The headlights are built with "open concept" - It's exactly the opposite of sealed headlights that work perfectly without trouble.

-- Either nearby wet air moisture enter the headlights and condensates on the cold front fascia
-- or water enters through openings and leaky harness connectors.

> The result is liquid water puddles at the lowest point where the unsealed electronic module is conveniently located...
What could not go wrong??

Again this is an example of non-compliant technology - HELLA Corp wants to sell open unsealed headlights that are not waterproof with electronics less protected than a cheap vacuum cleaner... that's amazin'

I have visited the solderless modules to protect them but have not identified an 100% fix used to channel water... siliconed the connectors is only a quick 5mn step!

 

Just curious .....what did you learn about the headlights from your appointment?

 

Seema like a skit by Saturday Night Live, where an air injection is needed to provide operating headlights on a six figure automobile.