Slight dampness in headlights

SteveChester · 04-10-2018, 04:46 PM

Hi what's the issue and fix?

I've got a slight layer of condensation inside my headlights.

DaveA · 04-10-2018, 04:56 PM

Just about every car I have had with sealed lighting units with plastic fronts has had this over the last 15 years or so... to some extent... and it seems to come and go with the seasons... reducing in warmer weather...

Not sure what causes it other than (i guess) slight air leaks causing moisture in the warmer air in light to condense on the inside of the cool front element...

Even if you change the units, it can still happen...

I also had it in rear light units..

Jeff123 · 04-10-2018, 04:59 PM

They are sealed units but not airtight units.

Hairdryer is the fix, or it was for me.

teaston · 04-10-2018, 06:16 PM

Condensation is normal, water droplets are not and will mean new light under warranty.

Watsey · 04-11-2018, 03:31 AM

The large access cap on the rear of the headlight unit (accessed through the wheel arch liners) are water resistant but not watertight. The hairdryer approach would work, or just leave the access caps off on a warm day with the car facing the sun.

Jeff123 · 04-11-2018, 03:43 AM

Quote:

Originally Posted by Watsey

The large access cap on the rear of the headlight unit (accessed through the wheel arch liners) are water resistant but not watertight. The hairdryer approach would work, or just leave the access caps off on a warm day with the car facing the sun.

I kept the hairdryer on for quite a long time, maybe 5-10 minutes, until all the condensation was gone. It came back a few days later, but there was less of it. I did the hairdryer treatment again and that fully cured it.

An alternative, or addition, is to keep the headlights on full for a few days.

Mine was so bad, I actually took it into the dealer to see if I could get it replaced.

xenon · 04-11-2018, 04:21 AM

Keeping headlights on will only dry them out if you have halogen headlights; LEDs and Xenons do not get hot at the front.

Jeff123 · 04-11-2018, 04:23 AM

Quote:

Originally Posted by xenon

Keeping headlights on will only dry them out if you have halogen headlights; LEDs and Xenons do not get hot at the front.

Yes, my problem was with an E90 many years ago.

NISFAN · 04-11-2018, 07:32 AM

Silica gel sachets in for a few hours will dry out the air. Which a blow dryer or heat from the light bulbs won't.

Watsey · 04-11-2018, 08:13 AM

Quote:

Originally Posted by NISFAN

Silica gel sachets in for a few hours will dry out the air. Which a blow dryer or heat from the light bulbs won't.

I was going to suggest the exact same thing, then thought they might be a fire risk if left in and headlights were on

JoeF36 · 04-11-2018, 02:56 PM

This is what I did back in February on a rare sunny afternoon and the condensation hasn’t returned:

- warm sunny day. Park car with front facing the sunlight.
- lift bonnet, unscrew the caps on the 2 headlamp units and leave them aside.
- drop bonnet but leave it off the latch.
- go and have a cuppa.

20-25 mins later, they’ll have dried out. Put the caps back on. Job done.

NISFAN · 04-11-2018, 03:30 PM

Quote:

Originally Posted by Watsey

Quote:

Originally Posted by NISFAN

Silica gel sachets in for a few hours will dry out the air. Which a blow dryer or heat from the light bulbs won't.

I was going to suggest the exact same thing, then thought they might be a fire risk if left in and headlights were on

I didn't mean drive around with them in.

Nobby Clark · 04-11-2018, 03:43 PM

The units aren’t hermetically sealed. There are removable access covers and moisture will get sucked in when the temperature changes
To avoid condensation, they need to be hermetically sealed otherwise any moisture in the unit at point of manufacture while condensate as the temperature drops
Water ingress is a different issue. If you have that there is a leak.

Watsey · 04-11-2018, 04:08 PM

Quote:

Originally Posted by NISFAN

Quote:

Originally Posted by Watsey

Quote:

Originally Posted by NISFAN

Silica gel sachets in for a few hours will dry out the air. Which a blow dryer or heat from the light bulbs won't.

I was going to suggest the exact same thing, then thought they might be a fire risk if left in and headlights were on

I didn't mean drive around with them in.

I know

Soul_Glo · 04-11-2018, 11:08 PM

Quote:

Originally Posted by NISFAN

Silica gel sachets in for a few hours will dry out the air. Which a blow dryer or heat from the light bulbs won't.

+1 taped 5 together and left in overnight

Russbmw · 04-12-2018, 05:30 AM

As noted above, it's condensation and, unfortunately, is normal - particularly on the front because of this:

Quote:

Originally Posted by xenon

Keeping headlights on will only dry them out if you have halogen headlights; LEDs and Xenons do not get hot at the front.

The headlights simply don't get hot enough to burn of the formed condensation if they are xenon or LED, and the headlights are completely water tight.

You can take the covers off the back of the headlight, heat up the headlights from the front with a hairdryer and leave it overnight (with the covers off) to cool down and temparatures stabilise. This will cure it temporarily. Sometimes you can get lucky and have a cool and dry night, and you might get all the moisture in the headlight air out, but chances are you'll have to repeat the procedure a few times.

Rear lights, you can't do anything about it. I had quite a lot of visible water droplets formed in mine after the car was about a year old, and had both lights replaced under warranty with no quibble. New ones dont' seem to have developed any similar problems yet, and we've been through a pretty cold and damp winter this year. Al I had was a very small amount of condensation vapour on one or 2 days, but that's been it.

04-10-2018, 04:46 PM	#1
SteveChester Brigadier General 2472 Rep 4,653 Posts Drives: F82 M4 Join Date: Oct 2009 Location: Chester iTrader: (0) Garage List 2014 BMW F82 M4 [0.00]	Slight dampness in headlights Hi what's the issue and fix? I've got a slight layer of condensation inside my headlights. __________________ Steve Roberts UK F82 M4 I'm running the 2024 London Marathon for the British Forces Foundation - https://www.justgiving.com/fundraising/sr5/
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04-10-2018, 04:56 PM	#2
DaveA Brigadier General 1881 Rep 3,433 Posts Drives: BMW M135i xDrive Join Date: May 2013 Location: Teesside iTrader: (0)	Just about every car I have had with sealed lighting units with plastic fronts has had this over the last 15 years or so... to some extent... and it seems to come and go with the seasons... reducing in warmer weather... Not sure what causes it other than (i guess) slight air leaks causing moisture in the warmer air in light to condense on the inside of the cool front element... Even if you change the units, it can still happen... I also had it in rear light units.. __________________ CAR HISTORY - Golf GTI 245 - F30 340i M Sport - F30 330d M Sport MPPK - F30 320d Sport - 997 Gen2 GT3 - 987 Cayman S - 986 Boxster S - Ibiza Cupra - Polo 16v - E30 M3 (Official GB import) - Integra 16v - Mk2 Polo S - Mk1 Golf C
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04-10-2018, 04:59 PM	#3
Jeff123 Jeff 318 Rep 1,451 Posts Drives: 330d M Sport x-drive F30 Join Date: Jan 2010 Location: Yorkshire iTrader: (0)	They are sealed units but not airtight units. Hairdryer is the fix, or it was for me.
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04-10-2018, 06:16 PM	#4
teaston Banned 10998 Rep 32,881 Posts Drives: X3 M40d Join Date: May 2012 Location: The High Seas iTrader: (1)	Condensation is normal, water droplets are not and will mean new light under warranty.
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04-11-2018, 03:31 AM	#5
Watsey Major General 6431 Rep 8,504 Posts Drives: F31 330D sDrive M Sport Join Date: Jun 2015 Location: On sabbatical. iTrader: (1)	The large access cap on the rear of the headlight unit (accessed through the wheel arch liners) are water resistant but not watertight. The hairdryer approach would work, or just leave the access caps off on a warm day with the car facing the sun. __________________ Current : F31 330sD, remapped, Ohlins Road & Track, Millway camber plates, Quaife LSD, Stoptech brakes + Pagid RSL1 pads all round, Weichers front strut brace, Eibach front & rear anti-roll bars, Michelin MP4S.
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04-11-2018, 04:21 AM	#7
xenon Major General 1402 Rep 8,088 Posts Drives: 2021 G21 330i M-Sport Join Date: Jun 2008 Location: Coventry iTrader: (0)	Keeping headlights on will only dry them out if you have halogen headlights; LEDs and Xenons do not get hot at the front. __________________ Ian Current: 2021 G21 330i M-Sport Previous: 2018 A6 Avant S-Line MMI+, 2014 F31 320d M-Sport, 2013 F10 520d M-Sport, 2011 F10 530d M-Sport, 2008 320i M-Sport Coupe, 2002 325i, 2001 318i valvetronic, 1998 318i, 1996 525i, 1990 Porsche 944S2
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04-11-2018, 07:32 AM	#9
NISFAN Major General 3489 Rep 9,709 Posts Drives: BMW M2 Join Date: Aug 2012 Location: Bedford UK iTrader: (0)	Silica gel sachets in for a few hours will dry out the air. Which a blow dryer or heat from the light bulbs won't.
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04-11-2018, 02:56 PM	#11
JoeF36 New Member 25 Rep 24 Posts Drives: BMW 420d M-Sport Join Date: Jan 2018 Location: Ireland iTrader: (0)	This is what I did back in February on a rare sunny afternoon and the condensation hasn’t returned: - warm sunny day. Park car with front facing the sunlight. - lift bonnet, unscrew the caps on the 2 headlamp units and leave them aside. - drop bonnet but leave it off the latch. - go and have a cuppa. 20-25 mins later, they’ll have dried out. Put the caps back on. Job done.
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04-11-2018, 03:43 PM	#13
Nobby Clark Lieutenant Colonel 759 Rep 1,863 Posts Drives: F36 430d xDrive M Sport Join Date: Dec 2015 Location: Scotland iTrader: (0)	The units aren’t hermetically sealed. There are removable access covers and moisture will get sucked in when the temperature changes To avoid condensation, they need to be hermetically sealed otherwise any moisture in the unit at point of manufacture while condensate as the temperature drops Water ingress is a different issue. If you have that there is a leak.
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