deilenberger

Recently I'd noticed the output from my HID factory headlights didn't seem to be what it used to be. SWMBO's Lexus RX350 had better lighting, and that just isn't right. After refinishing the front surface of the headlight (by polishing it out then coating it with a Dupli-Color clear coat made for headlights) - there wasn't much improvement.


I had one of the small parking lights crap out - so I had to remove one of the headlights and open it up. Curiosity prompted me to pull out the HID "burner" to see if I could find any reason for the lower output. I rather expected at 82,000 miles that I might see some darkening of the glass envelope.. but to my surprise, this is what I found:





Both bulbs had these deposits on them. I've never had any condensation problems with the headlights, and it appears that the '06 headlights have an air filter of some sort on the bottom of the housing, and the rubber tube on the rear cover for the housing (which isn't really an "open" tube - it has a sort of nozzle on the end so stuff can go out, and not go in.)



Both bulbs were the same, both had this coating on it. The coating didn't come off with gentle fingernail picking, so I ordered two new Philips bulbs from Amazon (about $116 for the pair - and they were genuine Philips - authenticated on Philips webside with the codes on the packaging.) Obviously the new bulbs didn't have this coating/film on them.


Things are now back to the expected brightness. As to what caused the crap on the burners - I'm puzzled. I know at one point with the early P!G there were condensation problems, and Porsche addressed this by putting packets of desiccant (silica gel) inside the headlight housing. I couldn't find any packets of desiccant - but I wonder if Porsche put the desiccant into the filter looking thing in the bottom of the housing.. If a desiccant salt was used I could see it being absorbed by moisture inside the housing, then deposited out at the hot spot on the HID burner. The burners were the original ones installed by Porsche at the factory (Osram Xenarc.)


Puzzle.. anyone else seen this? Anyone else want to look at theirs? I may try a bit of acid on a Q-Tip to see if I can dissolve the crap without damaging the quartz envelope/bulb.


More on silica gel: http://science.howstuffworks.com/inn...uestion206.htm

Note - also posted on Renntech..

I can update this - after driving for an hour tonight after dark it really became evident what was missing.. light. The lights are now as good as or superior to the Lexus HID servo-controlled projectors..

Dilberto

Hope that D1S bulb was NOT an Asian counterfeit....

Dennis C

HID headlights lose intensity and change color temperature with time and use. I'm not surprised that new bulbs offer a significant improvement.

deilenberger

I tried to avoid counterfeits by:

1. Ordered directly from Amazon - not from a seller on Amazon. The bulbs came right from the mothership..

2. Checked the holographic codes on the boxes. To fight counterfeits, Philips has a scanned code on the box, that opens a website at Philips on your smart-phone, where you then enter another code that is embedded in a holographic insert on the box (like on credit cards - but individual codes for each box).. and the website tells you if the bulb is genuine. In this case - the bulbs passed.

So I'm fairly confident they're not counterfeit. They also weren't as cheap as some of the ones being sold by aftermarket vendors, who had complaints about short bulb life and possible counterfeits (that's where Amazon reviews are really useful.)

XR4Tim

Every used D1S bulb I've seen looks like this, even if they haven't been used very long. I figured it was just a normal occurrence in the function of the Xenon bulb.

deilenberger

That's entirely understood, and was expected. This is DIFFERENT.

If you read up on HID light output vs use - they actually stay quite good for a very long time, then start to fail precipitously. There is some very early color shift and intensity loss - in the order of 5-10%, then the output curve vs time is almost flat until near failure.

According to several sources (who may all be drawing from the same data..) expected lifetime for HID burners like the D1S is 2,000 hours. At an average speed of 50MPH - that's 100,000 miles - driven at night when the HID light is on. The majority of my driving is daytime (I'm old..) so I'd have to posit that I haven't gotten near 2,000 hours on these bulbs.

The difference that I've tried to point out is - THE PROBLEM IS A COATING DEVELOPING ON THE EXTERIOR OF THE BULB. That isn't normal, that isn't how the bulbs are expected to change. That is abnormal and puzzling.

I'm curious if anyone else has actually LOOKED at their bulbs and what they've observed. Posting known general use related failure modes really isn't answering the question.

deilenberger

Tim - you wouldn't happen to have any photos would you? I can't imagine this being "normal" since it greatly reduces the output of the headlight. I've looked at used HIDs on conversion kits, and factory ones (I believe D3S's) on BMWs, and haven't noticed this before..

The design notes I've seen are the outside envelope is there to stop UV, and in case the active sphere explodes - it keeps the shards from getting into the headlight housing.

Dennis C

I've read and researched quite a bit about HID headlights. I've changed them on my 996 and my Cayenne after about 10 years of service and you really can tell a significant difference. I've only had a true failure of an HID bulb once, back on my 2003 Saab 9-5. It was only a couple of years old, but it suddenly turned very purple and wouldn't produce much light.

I've never noticed anything on the outside of the bulb when I changed them, but I haven't really looked.

deilenberger

I suspect you would have noticed this.. it's really obvious if you even glance at the bulb..

XR4Tim

I think I have a couple of old bulbs at home. I will have a look tonight if I get the chance. I seem to recall the haze being on the inside of the glass though. I will report back with my findings.

XR4Tim

Sorry, I hadn't had time to get to my garage until last night.
I had two D1S bulbs. The one on the left is an Audi bulb made by Phillips, and the one on the right is a Porsche bulb made by Osram. Both bulbs have very limited use. You can see the hazing on the Porsche bulb.

deilenberger

Tim,

Thanks. Confirms what my thinking was - that something in the Porsche headlight housing is outgassing and depositing on the HID bulb. That inspires me to play a bit and figure out how to remove the haze..

More stuff after I play with a few chemicals..

hahnmgh63

Looked around and found my one good D1S that I stored after replacing both of them for a bad bulb/ignitor a couple of years ago. The one that still worked does have a little haze on it, on the outside. But not as bad as the one in either of the pics. My pig is a early '06CTTS (11/05 build) with the bulbs replaced around June/July 2011.

deilenberger

Resolution..

I tried acetic acid (happened to be what I had kicking around in the darkroom..) It had no effect on the coating. So - I decided mechanical means were needed.

Used some 3M Perfect-It Rubbing Compound (actually a very fine polishing compound) rubbed on with a paper towel, then careful rinsing with plain water.

It took a few tries - but it cleaned off the coating.

A before:



An after:



Side by side - left one polished, right one untouched:


Good as new? Probably not since there is still a bit of hazing/deposits on the inside of the sphere where the arc takes place.. but bet it's about double the light output of what the bulb provided before, and much less diffuse (ie - better beam quality.) If you're hesitant about spending $150-200 for HID replacement bulbs (that's what good ones that aren't counterfeit cost) this would seem a viable option.

Before use - the bulb has to be carefully cleaned of any finger-oil that has gotten on it (the oil will char and burn into the quartz, possibly causing it to fracture.) I usually use pure ethanol (200 proof stuff) to clean bulbs before installing them. Probably some MAF cleaner would be equally as effective (and won't leave deposits.)

The question of what causes this - since it seems unique to Porsche HID headlights is still up for debate, but my WAG is - if you look at the photos where the headlight is disassembled - there is what appears to be a vent in the bottom of the headlight housing, with some sort of filter material. I'm betting that the filter material has a layer of silica-gel to keep moisture out of the headlights. I'd bet this eventually gets saturated and outgases fumes that then deposit on the hot spot on the HID bulb.

You can see the filter in Navaro911's picture from his thread on disassembling and painting headlight housings:


It's the white thing in the right corner of the housing bottom. On the other side it sticks out of the housing about 1/2"..

At least I now have a useable spare bulb to put on the shelf instead of just throwing them away.

Dilberto

OP - how did you "carefully" rinse this electrical part?