Rear lights condensing on MG4 SE

[Les burrows]

[ Edit moderator: see also these possibly related threads and posts:
MG4 Trophy - Crack showing in boot perspex
MG4 Lights cracked in heat
Interesting scratches inside the rear spoiler
]

Has anybody else noticed this on the MG4? Another to add to the list for my dealer.
Les

 

[Hallix73]

They all do that. Clears in the warmth.....eventually.

 

[Buster72]

They all do that. Clears in the warmth.....eventually.

But that is not good because it is indicative of moisture getting in.

 

[Les burrows]

They all do that. Clears in the warmth.....eventually.

Should not be happening I don’t think and it’s only on one side but yesterday while at a body shop sorting a repair out for my wife’s car I asked the chap there about it and he said it does happen on some cars the worse ones being Tesla.i will it address with the dealer next week
Les

 

[Davecut1]

Yes I noticed my car also does this, but i am not going to let it bother me. There are other things more importantly to be concerned of. Ant way show me the perfect car! The only concern I have is sorting out a tow hitch, if there are still no options when the weather improves I may design my own.

 

[Hallix73]

Should not be happening I don’t think and it’s only on one side but yesterday while at a body shop sorting a repair out for my wife’s car I asked the chap there about it and he said it does happen on some cars the worse ones being Tesla.i will it address with the dealer next week
Les

The clear plastic cover is not watertight, think it has breather holes in the bottom?.
I believe the LED light cluster underneath is watertight.
I have the Trophy and even the long center part gets this on wet cold days.
Soon drys out in sun or warmer weather.

 

[Cocijo]

I’ve had this on a couple of cars. One - a Tesla Model 3 had a new lamp fitted.
I was told that it is normal too and I have seen it on quite a few cars.
I still can’t help feeling that having water inside a light unit can’t be good for it over time.

 

[Auto Surgeon]

It's not normal unless the light cluster has been compromised, it looks more & more obvious that they are building to cost, that being they start at only $18k US in China.

 

[Les burrows]

The clear plastic cover is not watertight, think it has breather holes in the bottom?.
I believe the LED light cluster underneath is watertight.
I have the Trophy and even the long center part gets this on wet cold days.
Soon drys out in sun or warmer weather.

So why only one that does it other side is ok.
Les

 

[PeteC]

It's not normal unless the light cluster has been compromised, it looks more & more obvious that they are building to cost, that being they start at only $18k US in China.

I don't think it's a case of the cluster being compromised. As @Hallix73 says, the covers have little breather holes in the bottom, so they are not sealed covers. Mine (Trophy) do the same and dry out/clear once warm.

 

[john andersen]

We have made parts at my work to minimise this on aston martin cars.....

 

[Hallix73]

So why only one that does it other side is ok.
Les

Probably just wind direction and that side cooler so it condenses more? I am not saying its a good look, I personaly dont like the plastic cover at all. Looks cheap and would probably prefer it was off. However its probably there to aid the back screen from not getting dirty.

 

[Cocijo]

It is more common in headlights than tail lights because of the additional heat when in use.
I think that here is a thread on here about the ZS where owners have added moisture absorbing packs inside the light to try to minimise it.
Loads of manufacturers have issues with condensation in lamps.

 

[Hallix73]

It is more common in headlights than tail lights because of the additional heat when in use.
I think that here is a thread on here about the ZS where owners have added moisture absorbing packs inside the light to try to minimise it.
Loads of manufacturers have issues with condensation in lamps.

Its not in the lamps though, just the plastic cover over the sealed lamp clusters.

 

[Auto Surgeon]

Its not in the lamps though, just the plastic cover over the sealed lamp clusters.

Makes more sense now, never seen sealed lights with holes in the bottom. Must admit I wasn't keen on those clear covers.

 

[Cocijo]

Its not in the lamps though, just the plastic cover over the sealed lamp clusters.

Oh ok - I’m not familiar with those lamps.

 

[NickHeynes]

So why only one that does it other side is ok.
Les

On mine it was (I think) because one lense was in the sun and the other in the shade.

 

[davz]

Another example of poor design

 

[Ian Key]

They need holes to allow the pressure inside the plastic cover to equalise otherwise it could crack.
To see what I mean fill a plastic bottle with hot water, empty it out and put the lid back on tightly. Put it in your fridge, or in this weather, outside and watch it crumple.

 

[davz]

Sealed light units are not airtight therefore there is no need for any holes which would increase condensation as more water vapour would be contained within the unit. The fog lights on my z4 are full of condensation because the gaskets have hardened and are no longer sealing.
Your example of the drinks bottle is stretching it….literally ?. The bottle, made from pet, is extremely thin walled at 0.25mm and will flex easily when subjected to an increase or decrease in pressure/volume. A rear light, made from 3mm PMMA, is a well known dimensionally stable polymer, it wouldn’t deform with the slight increase/decrease in pressure caused by the Sun/cold even if it was fully airtight, which it isn’t. Don’t drill holes into light units, it’s an internet lie, it will only allow more moisture heavy air into the light and more condensation, this is the problem with the mg4 light, the seals are not doing their job correctly. It could be a poor choice of material, a design or assembly error?