Water getting in and blowing brake lights

bandrach, Apr 30, 12:25am
I have a Subaru Legacy 2002, and somewhere water gets in to the light fitting and blows my brake bulbs. I can't even establish where the water is getting in, should I grab some sealant and go around the back window or do I need all new light casings? If that is even possible. Ideas and suggestions welcome. Thanks

rob_man, Apr 30, 12:41am
Often between the different coloured parts of the lense or the lense and the body of the lamp. A clear glue of some sort should work if you find this is the cause.

bandrach, Apr 30, 12:49am
Great, will give it a go. Thanks

kazbanz, Apr 30, 3:46am
First thing to do is remove the whole lens asembily.Check where it seals to the body to see if the sponge is wet.
Then if theres water in the lens tip it so each join in turn has water on it.
You will see the leaking one pretty quick.

dave653, Apr 30, 5:34am
I've drilled small holes in them in the past. Make/model is irrelevent.

gammelvind, Apr 30, 5:39am
Not recommended but have to admit on my current car to drilling a tiny hole at the lowest point in one lens when I couldn't find where it got in. Worked well and hasn't been picked up at the wof, then again it's only a 1mm hole.

franc123, Apr 30, 6:22am
Remove light unit, put lense face down and fill it up with water through the bulb holder holes over a sink or laundry tub. you will soon see where it is leaking out. Mark where the leak is, dump as much water as you can out of it, dry the area out and seal the leak with silicone or urethane. Let dry, retest as above and finish up with putting a cupful of meths inside, slosh it all about until no water droplets can be seen, dump out the meths and refit to car. Job done. Oh, if by chance you have drilled any holes in the lense, reseal those too, its no more legal to have holes in it than it is to have the water in there!

dave653, Apr 30, 7:04am
Recently put a lot of steel back in a BMW. Leaking light seals. The lights themselves had water in them, bloody things had a double lense. outer bit sealed nice and tight, couldn't drain the water! Hence the drain holes.

kazbanz, Apr 30, 9:11pm
Ive been doing the lens thing for years and never thought to toss some meths in there--learn something new every day

sooby, May 1, 8:48am
What does the meths do?

lookoutas, May 1, 9:01am
There's some pretty complicated methods here!
It can usually be done without removing the light.

Get a squirt bottle and put some soapy water in it.
Take one bulb out and stick an air gun in there, with a bit of something wrapped around it to form a seal - to a point.
Squirt the soapy water around the suspect areas, and pull the trigger.
Bubbles will form where the water gets in. Now do the sealing/glue bit.

Don't try re-pressurizing it until the gunk has set. Better off to trust your work, than blow it all back out again.

franc123, May 1, 10:49am
It completely absorbs what moisture is left in the lamp unit, and then evaporates away completely afterwards and has a semi cleaning effect while it does it. Its far superior and smarter than adding further contaminants in the form of other non evaporating chemicals and certainly better than compressed air which can induce more leaks and even in some cases introduce more moisture. You are trying to not only seal the leak and not create new ones with air pressure but also get ALL existing moisture OUT. Its only going to condense on the lense again if you don't.

dave653, May 1, 8:17pm
Good idea. Our Commy lights are also a sealed unit. can't split the lense from the housing. I'll try it as soon as the missus stops long enough for me to get it!

lookoutas, Feb 16, 6:08pm
Hands up franc - I should have suggested not using too much pressure. A rag wrapped around an air gun, usually releases enough air to not cause any problems.

Reminds me of the day I'd just repaired a boot spoiler after a drum had tipped off the front of my trailer.
Poked the air into a hole in one end to blow all the crap out, but the hole on the other end was too small to let it out quick enough!

Made two cock-ups in one day.

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