Cleaning the Low-Beams

The idea with these lights is that the fisheye lens combined with the specially shaped back mirror means that all the light goes through a very fine focus point, and so can be controlled very accurately - in the case of the low-beam lights, this control is by a special metal "shadow plate" that gives the "shape" of the light pattern.

All this complexity also means that there are lots of places for the lights to lose efficiency. Mine were dim, even with new bulbs, and on looking at them from the outside they looked milky too - but being BMW, they can be fully dismantled and cleaned with some care.

First, you need to get the headlight off the car. With a trusty Phillips-head screwdriver, pop the hood, and choose your side to work on. There are two methods of getting the whole lamp assembly out, but you always need to first:

• remove all the wiring - headlight and sidelight (careful - you can crack the plastic shaft on this)
• remove the bulbs - I've found the H1 bulbs break filaments if you jar them too badly
• remove the light trim... the picture below notes one of the two retainer plugs along the top edge; once the plugs are out (unscrew the spreader screw & pull out) there are catches near the center kidney grille and the indicator - just juggle carefully and pull it out.

Then you've got two choices: remove the lamp alone or the whole frame. The lamp is held into the plastic frame by 3 points - the ball-head screws that allow adjustment of the aim. The idea in removing the lamp alone is to heat the plasitic clips that seat the metal lamp lugs onto these screws, and when soft, pop them all off, releasing the lamp.
    I have NEVER successfully released these clips without breakages... the clips are fairly cheap, so you could just buy 6 (3 each side) and hack-up the originals if required. My method was cheaper & more involved - I removed the whole headlight frame (both lights) and the indicator as well, and checked and cleaned. The only real "wrinkle" in this approach is the two mountings behind the indicator - you can see them in the photo above.

Here's the details of the back of the indicator so you know what the "hidden" mountings are:

Once you've got clear access to the back of the lamp, it's self-explanatory to dismantle the projector assembly from the front lens assembly - be careful, the mirror bodies may look like they are diecast metal, but they are plastic and the screws are self-tapping.

Once apart, it looks like this - the main reflector (without the projection lens):

In summary, I cleaned my lenses and reflectors very carefully with a very clean paper tissue and methylated spirits... some have reported that they have had the silvering rub off, so I used no pressure and tested first on the edge of the mirror - the "test area". The residue appears to have been white plastic powder from the back of the outer-lens ring-reflector - the mirror was very dirty and not at all bright, as you can see. If you do clean the inside of the outer lens, be warned that the white bars on the inside may rub off - I wasn't worried.