Tail light lenses melting...

I know there's a problem with the wiring harness on the e46's but has anyone else had their actual lens melt? Both of mine just started doing it a few weeks ago. At first I thought someone bumped me just hard enough to push in the plastic and dent it but not quite crack it... but nope! Definitely melting! Yeah, I got some cheap smoked lenses but dang that must be getting hot! I'm doing the ground this weekend. This was more of a curiosity post than anything. It was a big surprise that's gonna cost me an extra $$100 just for doing a cheap (but cool) mod when I didn't realize there was a problem... until it was too late. Oh well, shoulda checked the recalls I guess!

I can't see how a wiring problem would cause this -- the wires and connections are way on the back side. Sounds more like the bulbs got hot (which they're expected to do) and that's what melted the plastic lens. I don't think bad wiring could make the bulbs burn any hotter than good wiring.

The bulbs could be the wrong wattage,or the cheap lenses are just cheap. Probably both.

sent from my ATARI sc1224

Originally Posted by HiHoBrian

The bulbs could be the wrong wattage,or the cheap lenses are just cheap. Probably both.

sent from my ATARI sc1224

It's most likely the fault of poor parts choices, not BMW.

Definitely cheap lenses... but the plastic is hot enough to MELT. This isn't Styrofoam, its hard plastic! Light bulb surface temps supposedly only heat up to about 260 degrees F from my understanding... and even cheap plastic doesn't usually melt until 400 degrees so I'm amazed (I used to work for an injection molding company). An overvoltage problem (which if the thread i read is correct is what is happening with the e46 tail lights) seems like it should blow the bulb before getting that hot... but who knows! Must be a good bulb LOL ...I'm not disputing the fact that it's a cheap lens! But still, 400 degrees is major, man! The bulbs are the OEM specified bulbs. Thinking of changing to LED next time just to make sure this doesn't happen again.

Originally Posted by choxor

It's most likely the fault of poor parts choices, not BMW.

So I guess BMW doesn't ever do anything wrong?

Originally Posted by sledge

So I guess BMW doesn't ever do anything wrong?

...not when it comes to melting a taillight lens, no.

This isn't an unlikely scenario. Bimmian originally released xenon-color bulbs that you could install for the interior. They got so hot that they melted the housing around it, and sometimes distorted the plastic covers.

Go to Autozone and get a pair of quality bulbs to be sure you have proper ones in there.

Originally Posted by HiHoBrian

The bulbs could be the wrong wattage,or the cheap lenses are just cheap. Probably both.

sent from my ATARI sc1224

I think it is most likely that. One other thing to check is the brake light switch. If that is sticking on, it will overheat the light assemblies and cause melting. They weren't designed to have the brake lights on steady for an hour or more.

There's no over-voltage anywhere near there. Everything runs on the battery at 14 volts (ish) max. If the bulbs are running hotter than they should, they are higher power than they should be. If that's not the problem, it's just crap plastic. Oh, if you happen to be a "two-footed" auto driver whose brake lights are on all the time, that wouldn't help, but I can't believe it's the whole problem.

Originally Posted by sledge

So I guess BMW doesn't ever do anything wrong?

BMW doesn't install cheap aftermarket crap in our cars, it's us who do it

Originally Posted by sledge

Definitely cheap lenses... but the plastic is hot enough to MELT. This isn't Styrofoam, its hard plastic! Light bulb surface temps supposedly only heat up to about 260 degrees F from my understanding...

Out in the open air or with good air flow, that might be true. However, the bulbs are in a confined and more or less sealed space. As long as the bulbs are on, xx watts of power are being supplied to it. Pretty much all of that is converted to heat, and the surface of the bulb will just keep getting hotter and hotter until something fails. The only cooling is through the surfaces of the light enclosure (sides and lens).

Originally Posted by joegr

They weren't designed to have the brake lights on steady for an hour or more.

You sure about that? It can easily happen in traffic. This is only the second report we've seen of melting lenses - the last guy had higher power bulbs, and this one involves a goofy mod. Stock bulbs don't have any history of melting stock lenses.

Originally Posted by sledge

So I guess BMW doesn't ever do anything wrong?

Originally Posted by Wolrab

You sure about that? It can easily happen in traffic. This is only the second report we've seen of melting lenses - the last guy had higher power bulbs, and this one involves a goofy mod. Stock bulbs don't have any history of melting stock lenses.

I've had it happen with a third brake light before, but I couldn't swear to the time frame. I doubt that anyone would hold their foot steady on the brake pedal for an hour. I'd put it in park (or use the parking brake if a manual) after a few minutes. If you are talking about heavy stop and go traffic, then there would be a bunch of short cool off times in there as the brake is released to move up a few feet every minute or so. The climate would be a factor too. It would be more likely to happen in the hot sun on a 100F day than in the shade on a 50F day.

Originally Posted by joegr

It would be more likely to happen in the hot sun on a 100F day than in the shade on a 50F day.

Sure. But it doesn't seem to be happening in any systematic way to the E46 population out there. When somebody has a melted lens, there's some other factor involved. BMW isn't perfect, but I'm having trouble believing that their tail-light design is so marginal that it will melt lenses if you're on the brake for an hour, but 10 minutes is ok.

Mine is a 2006 with *factory* LEDs, so I don't care. So there!

Sub'd for photos of said melted lens..

Originally Posted by Wolrab

Sure. But it doesn't seem to be happening in any systematic way to the E46 population out there. ...

I really do agree that the most likely thing is that the lens were cheap or the bulbs were incorrect. None-the-less, the fact that lens aren't melting in a systematic way does not invalidate the stuck brake light switch theory either. Unless, of course, you are saying that BMW brake light switches stick on a lot. I would assume that sticking switches is a very rare event, so if that could cause a lens to melt, melted lenses would be even rarer. I do know by experience that it can happen, I also know that it would be very rare. It is more likely that the OP's problem is the lenses he used. Still, I think there are other possibilities.

I do agree that it's worthwhile checking the brake light switch for sticking. Zero cost and easy to do. Just get out and walk around the back. Or back up to a white wall and press the brake a few times, see if it ever stays on. Try the cheap and easy stuff first.

Note that OP has lenses that ABSORB LIGHT (which I will never understand) and they almost certainly ABSORB HEAT too. They tend to go together.

Doesn't seem to be sticking on unless it's totally random. I've never been able to catch it and my friends haven't ever noticed it anytime they were following me.

And not a two footed driver! Although I've seen some pretty amazing rally car driver's fancy footwork and wish I had it like that... I'm just not that talented lol

It could be true that the lenses are trapping heat I suppose... I guess I was assuming that a heat source could not produce heat greater than it's surface temp. I suppose the increased temp around the bulbs surface could raise the surface temp since the filament is the peak heat source.

Oh well, this time I'll go for different cheap lenses lol. Sorry guys. Can't go with the stock look! Love 330's but I gotta be just a little different than all you stock runnin' guys... even if it costs me a lil extra cuz it fails. 'Course I guess I could just tint some OE's...