[Vwdiesel] [VW-TDI] Re: 2001 Golf headlight/blinker Qs

Val Christian val at mongo.mongobird.com
Thu Apr 16 12:36:08 PDT 2009

The VW headlights are a polycarbonate thermoplastic.  

Polycarbonates have high impact resistance, but low scratch resistance.
Small particles, including road dust, continously erode the surface, once
a thin, hard coating erodes off.  In some applications, a coextrusion is 
done for better weathering.  

Road salt is not a chemical cause of clouding, but may be a mechanical 
cause.  More specifically, the slurry of salt, sand, road spray with 
suspended dirt, and so on, contribute to the surface erosion of the

Items from CDs and DVDs to the canopy of the F-22 (largest production extrusion
of polycarbonate to date) are made from polycarbonates.  Unfortunately,
since the coatings help the material maintain it's optical properties,
and since they are worn off my road debris blasted against the VW lights,
cleaning up the surface will only be temporary.

[Note that toothpaste (a clay slurry) can be used as an abrasive to 
clean CDs and DVDs.  The flat clay discs act as knives, or a nano
plane of sorts, leveling the surface.]

I have not tried the various methods yet, but i will probably try progressive
wet sanding, followed by buffing.  Then I will likely use RVR, which is
a Rain-X like porduct made for polycarbonate aircraft windshields.
If Rain-X doesn't fog the surface, you could try Rain-X as well.  I would
recoat in a couple of months.

Wax may work.  UV blocking polymer coatings would work better, from the 
standpoint of weakening the surface of the polycarbonate.

Both ethonal and isopropyl alcohol are considered safe with polycarbonate
plastics, however methanol is no.  Methonal or methyl alcohol are common
in windshield washer formulations (blue juice).  So avoiding application
of blue juice to your headlights may help increase their life by some
small hard-to-measure amount.

A paint protective polymer coating may work, but I have not researched 
this.  I'm thinking of the "polyglycoat" wax substitutes.

Finally, rather than applying polymer coatings, one could apply a sacrificial 
contact adhesive material, which provides UV protection as well as 
abrasion resistance.  Since it's sacrificial, when it gets damaged or 
worn, it can be removed, and replaced.  Xpel is one such product.

In my case, I'll likely abrade the glass clear, and provide a polymer coating
such as RVR.  

Your mileage and clarity may vary.

> I have a 2003 TDI, Florida car now in SC.
> Headlights got fogged bad by mid 2007. I guess is the extreme sun/rain combination here in the south, defenately no salt
> After months of debating what to do, I found this product: 
> HeadLight Restorer/Defogger by CrystalView www.myheadlight.com
> Very easy to use and 100% restoration back to showroom quality on both my headlights [Believe me, I was ready to by me a new set of 2 headlight assembly for about $280.00 a piece, drive about 60k miles a yr, 40% at night]
> How much I paid for this? 29.95 plus SC 7%tax at Advanced Autoparts. I believe you can get the product from the website and pay s&h ontop of the 29.95 price.
> Just follow the instructions; a bit of water, a bit sanding, a bit of polishing and a sealant application and you are done!!
> All you need is provided in the bag, they also have a video you can watch were they show you "how to" do it...all in all about 20mins work per headlight. 
> Note- I had to put some painter's blue tape around the metal surrounding the headlights in order not to "scracth" it with the bit of sanding involved
> 2003 TDI 262K miles and still running very strong!
> dont forget to change your full synthetic oil...OFTEN
> --- In VW-TDI at yahoogroups.com, "Rolf" <rbp at ...> wrote:
> >
> > hey gang
> > 
> > 2001 Golf TDi
> > 
> > 2 Qs:
> > 
> > - how do I remove pass side headlight assembly?
> > cover is all clouded and needs to be cleaned
> > anyone know a DIY anywhere?
> > 
> > - I have a blinker that works intermittently
> > sometimes it blinks normally
> > other times solid on
> > this applies both left and right and to hazards
> > what could cause relay to work part-time?
> > 
> > thanks!
> > 
> > Rolf in MA
> >
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