C238 (E400) 2017 - water (condensation ?) in rear light, what is the cause and what's the fix ?

[anyweb]

hi, I've noticed water build up in one of my rear lights (maybe both but worse on this side), I don't see any cracks in the plastic lens, so is it leaking in from behind, if so how ? the car is only a few years old it amazes me how crap the sealing is on them...

If i do have to remove the light to install a new seal, how do I remove the black plastic cover between the light and the boot lip seal ?

cheers
niall

 

[robin.large]

Not sure if it's the same thing but I have condensation in my headlights. Seals are fine. Dealer tells me it's 'normal' for LED lights to do this.
I remain unconvinced but can't find an obvious source.

Sent from my ONEPLUS A5010 using Tapatalk

 

[anyweb]

but this is much more dampness than I'm used to seeing on odd occaision in the front lights, you can see the drops quite clearly in these photos, i think some water has got in when high pressure washing the car but i can't see from where, does anyone have any removal instructions for these rear lights ?

 

[mioba]

Thats a-lot of moisture in there. have you tried removing the panelling in the boot. Once removed I guess there will be some wing type nuts holiding the lamps to the bodywork.
Get them out and a good hairdrier on the bench. That amount of moisture is not good for the LED electrics.
The seals will be either on the lamp or on the bodywork. Have you checked the lenses for hairline cracks.

Are those lamps original?

 

[anyweb]

the lamps are original as far as I can tell, I will try and open the panelling in the boot but would like to research the correct methods first, for example, how to remove that black plastic strip in between the boot lip seal and the light ? I don't want to break anything....

 

[anyweb]

ok i found this on youtube, it's not the same model as my car at all but hopefully similar...

 

[anyweb]

ok I tackled it by pulling aside the boot lining to gain access to 3 8mm screws holding the light in situ, i had to first remove two rubber grommets holding the lining and the parcel shelf net, then i could man handle it out of the way as in the video above...

but I'm no nearer solving the mystery, I have removed 5 t20 torx screws holding the back of the light to the insides but i don't want to break this as i'm sure it'll cost an arm and a leg to replace, any idea where the leak could be coming from ? I do not see any cracks in the plastic...

I am glad I moved the lining however as it exposed the Premium sound thingy and as in typical Mercedes fashion this expensive device is NOT protected from damp at all, before I re-assemble everything i'll place some plastic lining over the top of it (but not smother it) to protect from accidental drops....

 

[anyweb]

so i needed the car and decided to clean everything and put it all back together again, i did manage to remove the black plastic between the light and the seal, it's held in with three plastic grommets in green and one pin a t the bottom, 2 of the 3 green gromets had a rubber seal, could that be the cause (because one was missing) ? i doubt it... but maybe,

there was a lot of crap built up behind that black plastic, debris from the trees around my house I guess, so I gave it a really good cleaning,
i didnt have the same type of washer so put a small rubber washer on it to keep it tight, and cleaned everything up before putting the stuff back, also sprayed some wd40 into the wiring connector

I really don't know what is causing the leak and I don't know why there are 5 t20 torx screws as I cannot see what difference they make in getting the light assembly apart, does anyone know ?

 

[grahamcol]

The lights misting up thing bothers me on my 209 CLK. The headlights do this in winter but not much in summer. They're vented by design and l think it's normal for them to mist under certain conditions and then clear after a while. The tail lights mystify me though. My offside hardly ever mists but the nearside does. Again it seems to be a winter thing and generally it eventually clears on its own although occasionally l have used a hair dryer to assist things. I don't think there's a leak anywhere and my feeling is it's pretty much down to atmospheric conditions.

 

[anyweb]

you could be right, but i did find this non merc video where a guy uses silicon glue around the edges of the lights to seal them from damp, I might try the same if nothing improves. My 'dampness' in the rear right light was shortly after I high pressure washed the car recently, the weather has been bone dry and warmish so can't blame that, this time...

 

[Blobcat]

you could be right, but i did find this non merc video where a guy uses silicon glue around the edges of the lights to seal them from damp, I might try the same if nothing improves. My 'dampness' in the rear right light was shortly after I high pressure washed the car recently, the weather has been bone dry and warmish so can't blame that, this time...

“Self-inflicted” issues are always the most painful

 

[mioba]

Thats alot of water for a jet wash to be fair.
I would not let that self evaporate as that amount of moisture is not good for electrics and the internals.
Once you get the light off, hopefully the leak will become apparent.

 

[anyweb]

I had it off as you can see above, the leak was not apparent at all, I use the car every day so had to refit it, i looked very very closely at the light when it was off and could not see how the water got in....

 

[rada0309]

I got the same problem? Did you find a fix?

 

[rifiki]

Had same problem with Ford fusion and others. I just drill a pin hole at top and bottom at the back, not lens, of the light.
No more condensation or problems with jet washers

 

[grahamcol]

Had same problem with Ford fusion and others. I just drill a pin hole at top and bottom at the back, not lens, of the light.
No more condensation or problems with jet washers

Yes, it's often just a matter of adequate ventilation in my experience.

 

[anyweb]

I got the same problem? Did you find a fix?

I've seen videos where people had similar issues on non-mercedes cars, fixed them by drying the light somehow, and then applying silicon glue around the edge where the outer lens meets the back black plastic

I have not tried this yet as it involves taking the light out again, drying it (will take days, probably in the summer when i'm on vacation) and then apply the glue and refit

 

[rada0309]

I fix it At the back od tail light,you have white silicon cap. Just take it of!!