Headlight lens replacement, resealing and restoration

The front lens is bonded to the lamp body, so a cracked, yellowed or misted lens means either splitting it off and resealing it, or replacing it. Everything below comes from owners; there is no factory procedure for splitting the lamp. To take the whole headlamp out first, see Headlamp removal and beam adjustment.

Choosing: reseal, restore or replace

• Mist or water inside, lens fine. Split, dry out and reseal (below). Expect a mixed result, as owners disagree about how well it lasts.
• Lens crazed, yellow or cloudy. One owner restored very bad lenses by sanding and lacquering (below). It takes a long time. We don't know how well it lasts.
• Lens cracked or broken. Replace it. In 2012 owners said you couldn't buy the lens on its own, so it meant a complete new lamp, which they called very expensive, and a second-hand lens off a scrap unit was the hope. From 2016 an owner offered aftermarket lenses (see below).

Aftermarket lenses

• The lenses an owner supplied from 2016 were injection moulded, said to be comparable to the original in fit and quality, with a black edge and an internal ridge to help line them up. He said they were UV coated at the factory, and he cautioned that any UV coating wears out in time.
• They were sold with or without an E mark. The supplier's position was that the mark isn't needed in the UK because the lamps inside already carry E marks, and that the marked version is for places such as Germany, where the inspection can ask for it. That is his view and we haven't checked it.
• They were fronts only. Owners who bought them were pleased, and one said the fit was great.
• We don't know whether they are still available. Someone sent us this eBay listing as a place to buy lenses; we haven't checked what it is or whether it fits.
• Two videos on YouTube show the work: headlight removal and fitting aftermarket lenses.

Splitting the lens off

1. Heat a small section at a time and work round. One owner in 2007 used a heat gun on its lowest setting, pushed a feeler gauge into the softened joint and worked round, which took about 20 minutes with almost no scratches to the black paint. Others used a hair dryer, which one owner said was hot enough on its own, with a plastic lever; or a heat gun with a wide flat screwdriver and a craft knife blade on the stubborn parts.
2. The oven is disputed. One owner in 2016 gave the lamp about 10 minutes in a domestic oven at around 100°C (the figure in his post was garbled) and then ran a blade round from the top edge. Another had warmed the units in the oven and then split them with a heat gun, and said it worked well. A third, in 2007, said he wouldn't recommend the oven method for the fronts because of the metal parts inside, and had only tried it on rear lamps. If you try it, keep it gentle.
3. Touch up any black paint that comes away with a black paint stick. The 2007 owner said it couldn't be seen from the front.
4. Clean off the old adhesive from both the lens and the lamp body.

Drying and cleaning the inside

• With the lens off you can clean the inside of the lens and the reflector. One owner also gave the inside a coat of black.
• Let the parts dry out properly before sealing. One owner left his on a radiator in front of a fan heater for days, with all the bulbs out, and another said drying took longer than the rest of the job.

Sealing the lens back on

Owners used four different ways, none of which has a long track record in the posts:

• Butyl headlamp tape, then sealant. In 2016 an owner said to lay the butyl tape in one continuous strip, starting at the lowest point and working round, with one strip per headlamp. Once the lens is positioned and secure, go round the edge again with Tigerseal for a belt-and-braces seal. A 2015 restoration used butyl headlamp adhesive from the same supplier and Tigerseal in the same way.
• Black PU sealant. One owner in 2016 ran a thin strip on the lamp unit, pressed the lens on (no clamps were needed), wiped off the excess and, when dry, filled any gaps with more sealant.
• Double-sided foam tape plus black headlamp sealant. In 2013 an owner stuck the lens on with foam tape because it lets you fiddle it into position. It held so firmly he needed a hair dryer to pull it off the next day. He had no leaks a few weeks later. That is a short report.
• Clear silicone. Used in 2007, with the lamp reported as the same as before only cleaner. Another owner in 2013 had read that most sealants don't last and the lens will fall off.

Getting the lens in the right place is the hard part, so fit it dry first. The black edge on the aftermarket lenses is meant to help with alignment. A cracked black edge band can be repaired with black Tigerseal, according to the 2015 restoration owner.

Misting and condensation

• One owner in 2013 said the mist will always come back unless you are lucky with the reseal.
• Another resealed his with a lot of black mastic after drying them for days, and put silicone grease on all the bulb grommets. Two weeks of rain and snow later he had slight condensation in the corners again.
• An owner who followed a resealing guide in the oven-and-heat-gun style reported no misting five years later.
• Untested ideas from the thread: seal round the rubber bulb grommets as well, since that may be where it gets in, or vent the lamp rather than seal it completely. Nobody reported trying either.

Restoring a badly weathered lens

1. Split the lens off the body with a hair dryer and plastic lever, as above.
2. Sand with a block, horizontally only at first, with 60, 120 or 180 grit to remove all of the cracked coating. On his lens 60 grit took about 10 minutes and 180 grit about an hour.
3. Move through 320 dry, then 600, 800 and 2500 wet. Alternate the direction at each grade (the cross-hatch method), and don't move to the next grade until the previous scratches have all been replaced by the new direction.
4. Polish with a headlight restoration kit (he used a Meguiars kit).
5. Mask the inside of the lens, as overspray that gets in is hard to remove, and clean the dust off with white spirit.
6. Apply a UV-protective clear gloss lacquer (he used Rust-Oleum crystal clear gloss) in about five coats, from around 20 cm away at a very slow walking pace. Leave 30 to 60 minutes between coats. Too thin gives a cloudy orange peel, too thick runs.
7. Leave for 24 to 48 hours. Wet sand gently with 2500 grit to remove dust and orange peel without cutting through the lacquer, and polish again.
8. Reseal the lens as above.

One reader asked whether polishing before the lacquer was right. The owner said yes, that was what he did.

Loose or badly fitting headlamp

In 2010 an owner with one lamp that moved when pushed, and wouldn't tighten up, found that the wire to the indicator bulb was routed on the wrong side of the bracket that holds the lamp. It stopped the lamp seating. His fix:

1. Support the lamp (he put a cushion under it, in case it dropped), undo the 13 mm nut (he needed a short extension bar) and remove the bracket under it.
2. Withdraw the lamp carefully and unscrew the indicator bulb.
3. Route the indicator wire on the windscreen side of the bracket, as on the lamp that fitted properly.
4. Refit the bulb, push the lamp into place, refit the bracket and tighten the nut. He did it hand tight with a short extension.

• One owner whose lamp was loose after other work found the bottom clips had been broken and stuck back with Velcro, with the wire in front of the mount. He repaired the brackets with epoxy and metal and re-routed the wire.
• An owner who fitted a second-hand lamp that still had the bottom clips said it didn't fit well.
• Another owner taped the wire to the horizontal ledge rather than re-route it, and said the lamp was adequate rather than perfect.

See also Headlight bulb replacement.