rebuilding bi-xenon sealed headlights back to new sealed units

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W163ML500

Member
Joined
May 10, 2021
Messages
53
Location
UK
Car
Mercedes ML500 2002
Over my lifetime i used to re-seal many headlight units for people who could not afford new ones, and polish out the glass, and now plastic lenses to brand new again, no fogging, scratches, or hazy or milky lenses any more.
I am a bit of a perfectionist, as in I want the item to look as good as new, or sometimes better.
Stubborn and keeping going till the end gets me doing things until complete.

I will show how I now restore headlights, which you can do yourself at home.

The biggest problem is the oven needed to place the headlights into. So make your own, as I did in the images soon to follow.
The sealant on headlights is a product called Butyl.
It comes in various colours, and you must use the same colour as the original factory did, or your headlights will look funny. Normally black or grey.

First step: Make a box big enough to hold one unit at a time, and enough room inside to allow hot air to move around. Make a baffle inside to direct the heat gun around, so as not to have the heat gun putting all the heat in one area. As you look through the images, you will see how a built a baffle inside out of cardboard.
The lining with tin-foil was to keep the heat inside longer, rather than having to keep the heat gun on, as the heat gun is not controllable on the heat it gives out, so you will see how I managed this part.
 

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You use and need one particular temperature for this. trust me when I say this, as too many people seem to think , more heat will work better and faster, but also trust me when I say you will cause damage to all the internal parts of the headlight, including all solder parts and connections inside the unit, like ballasts etc.

You can place the entire headlight inside your oven, bulbs, everything.
You are only going to take the home made oven up to 110 degrees centigrade.
Not 120, or 130, as this is too hot and will start to cause problems.

You keep it in the oven for 20 minutes, and you get about 5 mins working time when you remove it to remove the lens.
This is too hot for our hands, so wear gloves when removing the light from the oven.
gently prise off the lens, with forcepts, pliers, screw-driver, but I use door trim pliers, as these are better for this job.
 

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Now you have the light out and the lens removed, while still hot, use a screwdriver, flat blade, wide enough to fit inside the groove with the sealant, and run the screwdriver round the sealant. You are only going to flatten down the sealant that is there already, do not bother removing it, as no need.
If it has cooled down too much to do this, then, oven for another 20 mins to soften the butyl again, and repeat as necessary.
You now have the lens off, and again you do not need to remove the sealant already there, but can if you want, and again, the lens will need 20 mins in the oven, and give you 5 mins to remove the sealant from the lens. Gloves again. the sealant will become pliable and sticky, so use this to touch the other sealant, and it acts like a sticky glue, and will help remove more of the sealant as you go.
 

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Now you have the inside of the light unit, the chrome coloured bit inside, which may be stained with water. If you wipe this off with a cloth, beware, you will also wipe the chrome effect spray paint, and if you do this, the bevel is then useless, and you will have to source another good bevel from a second-hand light you will them have to buy, but still cheaper than a new unit, so do not worry if you have to go down this road, as i had too on one of my headlights.
 

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so, after you have your new bevel, and of course used the oven for 20 mins on your new sourced bevel, from a complete second-hand unit, you can then use this to rebuild your soon to be new headlight unit.
Plastic chrome paint does not come in rattle cans, and too many sellers sell fake chrome paint in the world that is actually only silver paint.
The can top has been professionally sprayed with chrome paint, but the contents are NOT chrome paint.
The plastic chrome paint is 2pac, 2K, or something along these lines, NOT a single rattle can, so do not attempt to spray them, but if you know a company that can do professional chrome painting on plastic, use this service. Remember, the top lid is chrome, but the paint inside the rattle can is NOT chrome paint, but silver.
 

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The butyl comes in a cardboard box, like this. You need to put the whole box in the oven, but only for 5 mins to make it pliable, then pull off a bit, and remember you are going to roll it out into a long thin snake. You can soon work out how much the original light used from the factory, and use the same amount. Too much and it will spill over when you go to push the lens back on to seal the unit once more from the elements.

If you get it wrong, do not worry. you can keep doing this stage over and over till you learn.
It will be 20 mins each time in the oven with the complete unit, and 5 mins of work time to remove it and try again.
The idea of the rolling of the butyl, is too allow an even roll around the groove in the light, so not a fat rolled line that spews out over the sides.
If you keep the butyl at about 20 degrees room temp for 24 hours, this will also be enough to let you roll it into the size you want of a snake to fit round your light inside, where you have used a screw-driver to flatten the old butyl.
 

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Also on youtube, videos of others doing this in actual ovens will help you, as you see it in action getting done, as images are sometimes not the best way to get a point across.

My units slowly getting re-built by me. You will notice someone has replaced the bulb with an after-market HID unit and ballast, and cut a hole in the rear bulb cover, so this off course made the light non-sealed right away. I replaced with proper bulb and ballast, and used the cover off another light i bought for the inner bevel, so now no hole in the cover.
I also cut out there re-wiring for this bulb, and fixed the loom back to a sealed one again, with-out extra wires and plugs.
 

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My finished headlights, and polished lenses.
If you want me to show and explain how to do the polishing of the lenses, i'll do a thread, but lots of youtube videos show this part already, not very well though, as they do not use the correct finishing method, and your lights will tarnish and get oxidized in no time, by the suns UV rays, as they have to be sealed after being polished with a clear UV spray-on sealant for plastic and glass lens.
 

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This may be long winded and maybe not needed to be explained so much, but please understand I stuggle with communication now and getting my point across, so this is the best i can do to show instead of a live video feed.
If you want your lights and lenses back to new, let me know, I do help out others at times with this one.
 
Great write up . Something similar here from Alex on legitstreetcars. The jury is still out for me on the blacked out look .

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It’s things like this that make the car forums worthwhile. When I was on m3 cutters, I managed to get a discount for the vanos being done by mr vanos for a few on there.
My front lights have cracking and need replacing, though a local guy came and polished them up for £30. Did a good job, and took all the milkyness out of them.
 

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