How much headlight condensation is acceptable

[Goran Hristov]

It's a growing problem because the air volume within car headlamps is increasing, because headlamps are getting bigger. They're getting bigger (have become bigger) due to both styling and crash reasons.

Styling- headlamps are now part of the styling function of the car. Now they've evolved beyond 7" SBRs they cam be made into all kinds of different shapes; they contain beam shaping technology and may also shortly contain distance sensing and P2P wireless communications technology too. A car headlamp isn't a lamp in the traditional sense, it's a box of electronics that glows*.

Crash- the headlamps are one of the first elements of the car to be involved in a frontal impact and none more so that in a pedestrian impact. So, they're designed with this in mind, they form an integral element of the frontal crash structure. The attachment brackets are designed to break off above a certain force; MB are very good in that their brackets are pre-weakened, and repair kits are available. So presuming that the lamp isn't destroyed in the collision, for a £30 repair kit a £1000 headlamp can be put back into the car.

So, because a car headlamp now has a (usually much bigger) lens area exposed to the outside air, its ability to condense whatever content water vapour exists in its (much greater) internal atmospheric volume increases. And also, because lamps now generally run cooler than they did (incandescents @ 250 C, halogen @ 180 C, HiD @ 150 C, LED @ 55 C), their ability to boil off condensate has significantly decreased.

Now we have an issue where the problem has become harder to solve and the solution has become weaker in its effects............



Car headlamp PCBs are all conformally coated with waterproof varnish for this specific reason. Besides which, the PCBs don't exist at the point of condensation (the lens), they are buried much deeper in the lamp unit in their own internal enclosure where the probability of condensation reaching them is much reduced.



No. Car headlamps are not "sealed" to atmosphere, they're usually rated to IP61 or IP62 e.g. "splashproof". There is no airtightness in any way. I say again they have breather vents built into them. The front foglamp units on my 215 each have 2 x U shaped rubber vent pipes attached as breathers. The lamp units have to have the ability to dispel moisture via evaporation, they're all designed with this in mind using vent patches (Gore Tex), vent plugs (foam rubber) or labrynthine seals.

My GLC 300 also has this problem from day one. Actually I read a lot of this "phenomen" and concluded that there is NO chance to beat it if the system is opened. But if I calculate that working temperature of air inside the headlight is in range from - 20 to +80 degr. C, so I could calculate what would be extended volume of air(if the air inside is preheated from - 20 to +80 degr as result of different factors :frost during parking to sun bathing+engine heat). Let say that air inside the headlight body is abt 4 ltrs, then with above temp range the extended air will be abt 1.58 ltrs(ttl 5.58).Thus if we connect the appropriate flexible "pot" to headlight with capacity abt 1.6 ltrs, after expansion the air in the system will remain with same pressure, but with bigger volume. In this way we could "close" the system and to avoid any suction of mist air. Also the air inside will be kept for safe transferring of the heat of LED system to enviroment. So for the extension "POT" can be used

 

[Goran Hristov]

My GLC 300 also has this problem from day one. Actually I read a lot of this "phenomen" and concluded that there is NO chance to beat it if the system is opened. But if I calculate that working temperature of air inside the headlight is in range from - 20 to +80 degr. C, so I could calculate what would be extended volume of air(if the air inside is preheated from - 20 to +80 degr as result of different factors :frost during parking to sun bathing+engine heat). Let say that air inside the headlight body is abt 4 ltrs, then with above temp range the extended air will be abt 1.58 ltrs(ttl 5.58).Thus if we connect the appropriate flexible "pot" to headlight with capacity abt 1.6 ltrs, after expansion the air in the system will remain with same pressure, but with bigger volume. In this way we could "close" the system and to avoid any suction of mist air. Also the air inside will be kept for safe transferring of the heat of LED system to enviroment. So for the extension "POT" can be used

The formula is V=NRT,but it is from physics.Yes it sounds strange, but there is enogh space in engine bay for two conteiners with "flexible pot" connected to headlight with small rubber hose. The most importan for the "pot" is that it should be flexible and deflated before connection to headlight body. Head light body should be sealed then. Sealing of headlight should be done, during dry conditions. For better result small amount of silicagel could be inserted in connection rubber line(to be easy for replacement). 1.6 ltrs for 4 ltrs initial volume is worst case, when range is 100 degr. Actually the extended air by my calculations will be abt 1 ltr, considering also very small overpressure (10%)of the system, keeping out any incoming air.

 

[Goran Hristov]

The formula is V=NRT,but it is from physics.Yes it sounds strange, but there is enogh space in engine bay for two conteiners with "flexible pot" connected to headlight with small rubber hose. The most importan for the "pot" is that it should be flexible and deflated before connection to headlight body. Head light body should be sealed then. Sealing of headlight should be done, during dry conditions. For better result small amount of silicagel could be inserted in connection rubber line(to be easy for replacement). 1.6 ltrs for 4 ltrs initial volume is worst case, when range is 100 degr. Actually the extended air by my calculations will be abt 1 ltr, considering also very small overpressure (10%)of the system, keeping out any incoming air.

PV=nRT

 

[Goran Hristov]

It's a growing problem because the air volume within car headlamps is increasing, because headlamps are getting bigger. They're getting bigger (have become bigger) due to both styling and crash reasons.

Styling- headlamps are now part of the styling function of the car. Now they've evolved beyond 7" SBRs they cam be made into all kinds of different shapes; they contain beam shaping technology and may also shortly contain distance sensing and P2P wireless communications technology too. A car headlamp isn't a lamp in the traditional sense, it's a box of electronics that glows*.

Crash- the headlamps are one of the first elements of the car to be involved in a frontal impact and none more so that in a pedestrian impact. So, they're designed with this in mind, they form an integral element of the frontal crash structure. The attachment brackets are designed to break off above a certain force; MB are very good in that their brackets are pre-weakened, and repair kits are available. So presuming that the lamp isn't destroyed in the collision, for a £30 repair kit a £1000 headlamp can be put back into the car.

So, because a car headlamp now has a (usually much bigger) lens area exposed to the outside air, its ability to condense whatever content water vapour exists in its (much greater) internal atmospheric volume increases. And also, because lamps now generally run cooler than they did (incandescents @ 250 C, halogen @ 180 C, HiD @ 150 C, LED @ 55 C), their ability to boil off condensate has significantly decreased.

Now we have an issue where the problem has become harder to solve and the solution has become weaker in its effects............



Car headlamp PCBs are all conformally coated with waterproof varnish for this specific reason. Besides which, the PCBs don't exist at the point of condensation (the lens), they are buried much deeper in the lamp unit in their own internal enclosure where the probability of condensation reaching them is much reduced.



No. Car headlamps are not "sealed" to atmosphere, they're usually rated to IP61 or IP62 e.g. "splashproof". There is no airtightness in any way. I say again they have breather vents built into them. The front foglamp units on my 215 each have 2 x U shaped rubber vent pipes attached as breathers. The lamp units have to have the ability to dispel moisture via evaporation, they're all designed with this in mind using vent patches (Gore Tex), vent plugs (foam rubber) or labrynthine seals.

I see, that You are quite familiar with the headlights. Could You advise me what are the highlighted parts? The grey membrane with yellow is supposed to be pfte membrane for ventilation? Thanks in advance.

 

[Craiglxviii]

I see, that You are quite familiar with the headlights. Could You advise me what are the highlighted parts? The grey membrane with yellow is supposed to be pfte membrane for ventilation? Thanks in advance.

From your image they look to be gaseous exchange breathers.

 

[ajlsl600]

at 1200 !!! you would think the gits would design them to work properly in the environment they are sold in.. its exactly for the reasons the OP started with i would not be buying any car so equipped. drill holes in it huh !! it would be going to benz they can do that.....

DTF !!!

 

[Goran Hristov]

From your image they look to be gaseous exchange breathers.

Yes, i think that grey is AVS-9 membrane, but for others I was not sure.

 

[JGM Douglas]

This is a known issue. Took my 3 1/2 year old GLC to my mercs garage with misted up headlamps, and they said it's a known problem. They fitted silica gel bags and not had an issue since. Apparently the new headlamps don't must up.

 

[joderest]

Have to add.
My W163 headlights on occasions have condensation on the inside of the lens, it looks awful.
Lucky enough that part of the car is a bit old school. 1 10mm bolt and 2 10mm nuts and headlight comes out, disconnect 3 plugs, takes about 3 mins to remove either headlight.
Remove plastic caps and indicator bulb, place upside down on radiator for about an hour, bit of rubber grease round the seals and pop it back in.
Lasts a month or so.
I do not know how water is getting in, but it's a quick fix.

 

[RhodieBill]

C200 AMG line 2014 with 14.5k miles only. Now on third and fourth headlamp units and yet again getting excessive condensation on inside of the lamp unit. MB have always said a little is to be expected and it will burn off as soon as the lights are on but this seems excessive and must deflect the beam for a while until it (maybe) clears.

I personally have considered none to be acceptable!

 

[nwady]

My 2014 s350d has terrible condensation on just passenger side ,drivers side has some minimal misting but pass side is ridiculous...
It's a 70k car not an 1970s allegro..!!!
Have just tried putting bathroom sealant along top of said light

 

[Archer]

Well now the nearside light unit has failed again - these sealed units have to be replaced as a whole unit and cost over £1200 each. This one was replaced as defective in July 2018 and the off-side is on its third unit. the car is just six years old and only done 20K miles. Now looking at sale of goods act under the 'fit for purpose' clauses!

 

[joderest]

It can only be a matter of sealing, however, warm headlight, cold air hitting front, condensation, unless there is some sort of airflow to get the condensation out, some lights have tubes to do this.

 

[RhodieBill]

Do you use a Jet-Wash on the car? - If so, don't - especially around the Light Fitting. You will be surprised where a powerful jet of water can get, especially travelling in excess of 250mph.....

 

[sonic]

I get the odd misting in my 212 2011 vintage, but it always disappears shortly after.

 

[Mirrorimage]

Hi my w205 2017 c220d Amg line has got same issue my car is still in main dealer waiting outcome

 

[RhodieBill]

Hi my w205 2017 c220d Amg line has got same issue my car is still in main dealer waiting outcome

Wow! That is BAD!

 

[Craiglxviii]

Wow! That is BAD!

It looks bad, but it’s really not. It could be far, far worse.

 

[RhodieBill]

It looks bad, but it’s really not. It could be far, far worse.

Yes, I suppose so. But then it would be called a Mobile Aquarium......

 

[Mirrorimage]

My car is Still in main dealer 3rd day still no report yet to if they are going to cover under good will my warranty has ended year or so now but it went into main dealing for the same issue under warranty and now it in there again