Headlamp lens renovation

[Parrot of Doom]

I spotted this on another forum and thought I'd give it a go. Heres the thread.

http://www.benzworld.org/forums/w210-e-class/1305149-headlight-lens-restore.html

I'll not dwell on the words too much as the pictures are mostly self explanatory.

Tools required - 8mm socket (long), medium flat blade screwdriver, small flat blade screwdriver, 1200 grit wet & dry paper, 1500 grit w&d paper, 2000 grit w&d paper, Meguiars plastic scratch-x polish, and a work surface with some form of clamp.

The lenses on the headlamps are plastic, which scratches more easily than glass. Fortunately its less expensive and lighter, which is why it gets used. Over the course of 10 years my headlamps are badly pitted and marked, they don't look too pretty. So I thought I'd see if I could return them to their original condition.

The principle is quite easy. All you're doing is sanding out the imperfections. It just takes time and patience.

You can use this howto for any model, only the location of the bolts that hold the headlamp in, and the design of the headlamp assembly, will be different. The same principles apply to the lens, no matter what shape they are.

1) Removal

Lift the bonnet up. Pull the rubber trim away from the lamp, and you'll see 2 bolts, both 8mm. They hold the lower plastic trim on the car (note that facelifted W210's do not have this trim). One on the top, one on the side. Remove both.





This allows the lower trim to fall away (it hinges on the wing side of the bodywork)



There are 3 bolts remaning, these hold the headlamp in. One is located on the top of the assembly, towards the wing of the vehicle. Another is where the trim hinges away. The other is located on the bottom corner, diagonally opposite. All are simple to remove.

Once these bolts are out, all that remains is to unplug the 2 electrical connectors on the back of the headlamp, and the vacuum connector that controls the height. Use the small flat blade screwdriver to remove the vacuum connector, and be careful - you don't want to break the plastic.

Once its out, you'll be looking at this:





If you've time, you can get a wire brush on that rust and paint over it with something like POR15. I'll be doing that in the summer I think. Its only surface rust here, nothing too bad. Its rusty because the previous owner had some work done, and whoever put the lights back in neglected to install the rubber seal that runs along the bottom edge of the headlamps - and water has gotten in over time. I have of course replaced this seal.

2) Headlamp construction

Right, this is what you should have now:



Pull that rubber trim away. Its held on by small clips, its very easy to remove.



Now we have to separate the lenses from the main body of the headlamp. You can see in the picture above there are several large clips which serve to hold the thing together. Get your large flat blade screwdriver out, and carefully prise each clip apart. They're clever Mercedes, they've designed the clips to be in 2 stages - one stage is a light 'click' separation, the next stage is the final 'clack' that allows you to pull it apart. Its so that when putting it back together, you can line everything up without committing yourself to closing any of the clips again. Very neat bit of design I thought!

Once you've got those clips apart, this is what you should see:



Theres a rubber seal that runs between the 2 halves. It seems to have worked perfectly on mine. The reflectors were absolutely spotless (apart from a tiny bit of dust). They're chrome coated plastic from the look of things, so will scratch easily. Best be careful.



Theres the inside of the indicator part of the lens. Another nice bit of design, it allows the indicator to effectively be invisible when the main headlamps are in use.

3) Polishing

Put the lenses on your work surface. I used a black and decker bench, and clamped it into place with rubber plugs.

[Parrot of Doom]

Wet down both the lens, and your paper.



Start with the 1200 paper, and keeping both surfaces wet, give it a good 10 minutes of sanding in a circular motion.



The creamy scum you see is the thin layer of plastic that's being removed by the paper.

Once you're happy you've done enough, dry it off and this is what you should see:



Looks horrible doesn't it? Don't worry. Get the 1500 paper out, and repeat the above step.



Getting better, but still not there.

Now I've not been able to find any 2000 paper yet. I will do shortly, and I'll give it another go. If you don't have any 2000 paper, not to worry, just continue onto the next step:

Get your Meguiars polish out, dry the lens off, and give the lens a good polish. Say 10 minutes for good measure. I used kitchen roll for this although cotton cloth is probably better. Later on, I used my orbital sander with a cotton disc.



Now I'd have to admit they look roughly the same. But heres what they look like under a flash:



The lens on the left is before - the one on the right is after.

Big difference! I'm going to continue tonight, I reckon another 20 minutes with the polish on my orbital sander will do the trick.

Re-assembly of the headlamps is the reverse of the above procedure. Make sure you wash all the surfaces that require sealing, and if you want to its worth lubricating the rubber parts with silicone spray.

I also used this opportunity to wire resistors across the LED sidelights in the headlamps. This gets rid of the bulb failure warning when using low current draw lamps.