That ruddy rear lght - DB9
Discussion
Yes, they all do that and my car has a history of eating rear lights, or rather just the nearside one.
When I went to view the 'accident-free' car 3+ years ago the NR light had condensation in it. 'We just washed it' said the dealer.
I subsequently found out that the car had been in an accident in that rear quarter.
A few months later warning lights started appearing and the dealer replaced the unit. Great.
A few months later warning lights started appearing and I sent the unit off to the man in Guildford for repair.
A few months later warning lights started appearing and I sent the unit off to the man in Guildford for repair again. Upon return it was still giving warnings though the actual lights worked. I learned to ignore the warning lights.
Last autumn the car failed its MOT because the brake light wasn't working. I managed to find a replacement unit on eBay and fitted it. All working again, lovely!
And now I see significant condensation inside
Eventually it will fail again, and Guildford man is not on my confidence list. I will probably have to pull it out and try the DIY oven trick.
My question is - do I try it now, while the light is still working perfectly, and risk buggering it up, or wait until it starts failing and then try it, by which time any damage to the circuits may have happened?
And finally, I know that misting headlights can have a vent kit fitted - has such a thing ever been done with a rear light?
When I went to view the 'accident-free' car 3+ years ago the NR light had condensation in it. 'We just washed it' said the dealer.
I subsequently found out that the car had been in an accident in that rear quarter.
A few months later warning lights started appearing and the dealer replaced the unit. Great.
A few months later warning lights started appearing and I sent the unit off to the man in Guildford for repair.
A few months later warning lights started appearing and I sent the unit off to the man in Guildford for repair again. Upon return it was still giving warnings though the actual lights worked. I learned to ignore the warning lights.
Last autumn the car failed its MOT because the brake light wasn't working. I managed to find a replacement unit on eBay and fitted it. All working again, lovely!
And now I see significant condensation inside
Eventually it will fail again, and Guildford man is not on my confidence list. I will probably have to pull it out and try the DIY oven trick.
My question is - do I try it now, while the light is still working perfectly, and risk buggering it up, or wait until it starts failing and then try it, by which time any damage to the circuits may have happened?
And finally, I know that misting headlights can have a vent kit fitted - has such a thing ever been done with a rear light?
I put my big boy pants on and did the DIY fix which, so far, has worked (4+ years). When doing it I found a tiny hole, maybe 3mm dia, drilled in the lens so a previous owner had tried that trick. Worth looking for if you do have a go at yours as obviously sealing that is necessary if you manage to get the rest of the light sealed. On mine the LED blade had failed due to moisture, but I found a chap who had a stock of working ones from when people did the Audi chaser light upgrade.
To the best of my knowledge there is no fan kit for the rear lights. My understanding is that the front lights are not fully sealed anyway by design whereas the rear lights are (meant to be), hence the fan works by creating slight over pressure of drier air. To do the same in the rear lights you'd have to deliberately break the very seal you are trying to maintain (or improve).
To the best of my knowledge there is no fan kit for the rear lights. My understanding is that the front lights are not fully sealed anyway by design whereas the rear lights are (meant to be), hence the fan works by creating slight over pressure of drier air. To do the same in the rear lights you'd have to deliberately break the very seal you are trying to maintain (or improve).
Manners79 said:
To the best of my knowledge there is no fan kit for the rear lights. My understanding is that the front lights are not fully sealed anyway by design whereas the rear lights are (meant to be), hence the fan works by creating slight over pressure of drier air. To do the same in the rear lights you'd have to deliberately break the very seal you are trying to maintain (or improve).
Thanks. It seems impossible to seal the unit properly once it's failed. I'm good at DIY but had no luck with my first attempt to fix.So rather than try to make it perfectly watertight, the Plan B was to accept it and provide forced ventilation instead. Even a pluggable hole at each end and a blast with a hair dryer would help!
Another idea, while it's apart drying out, is to coat the circuit boards with something impervious to water, a spray perhaps - but it would have to be non-conductive.
Simpo Two said:
Hey, you're the guy who can remove and replace a V12 engine! Reckon you can take on a DB9 light unit or is that pushing the skillz? 
Easy ! 
Put it in your oven, separate the unit, put it on/near your boiler for a week and reseal with proper sealant
You can replace the reverse lamp while your doing it as that's not LED.
Edited by paulrog1 on Friday 14th February 12:08
paulrog1 said:
Easy !
Put it in your oven, separate the unit, put it on/near your boiler for a week and reseal with proper sealant
Indeed. Is an airing cupboard adequate or is the oven better? Can you advise me what the best sealant is please?Put it in your oven, separate the unit, put it on/near your boiler for a week and reseal with proper sealant
Since the OSR unit works perfectly, there must be a way to do it. Sometimes I wonder whether tightening up the three retaining bolts inside the boot puts some kind of twist on it - but I only do them finger tight.
The current unit looked perfect when fiited
Simpo Two said:
Another idea, while it's apart drying out, is to coat the circuit boards with something impervious to water, a spray perhaps - but it would have to be non-conductive.
What you're looking for is called a "Conformal Coating". Here's just one example in a rattle-can from the well-respected RS Componentshttps://uk.rs-online.com/web/p/conformal-coatings/...
Simpo Two said:
Indeed. Is an airing cupboard adequate or is the oven better? Can you advise me what the best sealant is please?
Since the OSR unit works perfectly, there must be a way to do it. Sometimes I wonder whether tightening up the three retaining bolts inside the boot puts some kind of twist on it - but I only do them finger tight.
The current unit looked perfect when fiited
The oven is to separate the lens from the unit, the airing cupboard is to dry it out and remove all the condensation.Since the OSR unit works perfectly, there must be a way to do it. Sometimes I wonder whether tightening up the three retaining bolts inside the boot puts some kind of twist on it - but I only do them finger tight.
The current unit looked perfect when fiited
I would use Loctite 595 clear sealant, is very strong, flexible and watertight, great stuff.
Edited by paulrog1 on Friday 14th February 13:30
paulrog1 said:
The oven is to separate the lens from the unit, the airing cupboard is to dry it out and remove all the condensation.
I would use Loctite 595 clear sealant, is very strong, flexible and watertight, great stuff.
Ah I didn't realise the oven softened the sealant! I must do this next week. What oven temp/time do you recommend please? (presume door shut, it's a fan oven so presumably will suck out moisture).I would use Loctite 595 clear sealant, is very strong, flexible and watertight, great stuff.
Ah yes that thread, I remember that. I'm pretty good at removing and refitting the unit now. I also had a go at fixing an early one (just airing cupboard not oven) but it didn't work.
The old thread all makes sense apart from 'Remove the 3 little screws that hold the lights internals together'. So it sounds like some internal disassembly is required too, but exactly what isn't clear. Anyway, nothing to lose I suppose, and if I break it, well, it was going to break anyway...
The old thread all makes sense apart from 'Remove the 3 little screws that hold the lights internals together'. So it sounds like some internal disassembly is required too, but exactly what isn't clear. Anyway, nothing to lose I suppose, and if I break it, well, it was going to break anyway...
paulrog1 said:
I would use Loctite 595 clear sealant, is very strong, flexible and watertight, great stuff.
Thanks for this recommendation Paul. I used normal multipurpose silicone sealant when I did mine about a year ago and it started filling up with water again a couple of months ago. It's currently in the airing cupboard drying out again so I've just ordered some Loctitie 595 to seal it better this time hopefully.I've also got some Gortex patches to put over the hole I've drilled as I left them open last time. Anyone got any opinions/views an using Gortex patches or not?
V8V Pete said:
I've also got some Gortex patches to put over the hole I've drilled as I left them open last time. Anyone got any opinions/views an using Gortex patches or not?
I've found the best sealant to be SikaFlex 221, I use it in all my headlights with no issues.Gore-Tex is a waterproof membrane that lets water vapour through, so water will only escape through the membrane when it is warm enough for it to become a vapour - shouldn't make it any worse though.
Simpo Two said:
Surely if something can let moisture out, it can also let it in?
Only from the warmer side to the cooler sideSimpo Two said:
A Heath Robinson solution would be to drill a hole in each end of the light unit and route the hot air heating system through it... :spin :
Not as easy as the headlights, easily accessible hot air from the engine compartment.Simpo Two said:
Surely if something can let moisture out, it can also let it in?
A Heath Robinson solution would be to drill a hole in each end of the light unit and route the hot air heating system through it... :spin :
You don't have a Gore-Tex jacket in a cupboard somewhere?A Heath Robinson solution would be to drill a hole in each end of the light unit and route the hot air heating system through it... :spin :
Each square inch of the GORE?TEX membrane has nine billion pores. Each of these tiny holes is 20,000 times smaller than a water droplet. This is what makes the membrane in everything in the original GORE-TEX products range waterproof: rain and snow simply cannot get in.
....
Each one of those billions of pores is also 700 times bigger than a water vapor molecule, which is just a nice way of talking about your sweat! It means that, when you’re working hard, or the temperature rises, your sweat can escape.
https://www.gore-tex.com/blog/the-gore-tex-membran...
This means liquid water cannot get through, but vapour can. Any liquid water inside will remain trapped inside until it evaporates, and then I assume you'd need some air circulation to move the vapour molecules through the membrane. I'm also guessing if you were in a muggy environment with RH at, say, 95% then the atmospheric moisture vapour could get into the light unit
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