Open Road

just realized last week that 1 headlight was foggy and one was ok.
i have often found it on the newer style vehicle headlights that have clear plastic headlights and a good machine polish on the outside fixes them, but this was on the inside of the glass.
it is worse looking to the eye than the pictures actually show






a quick search online found a few other 928's suffer the same fate, with many repair methods
these headlights are the glass version from an 87 model.
and the next post is how i fixed mine.
now just need to take some pictures of what i did so might help someone in the future
cheers
Phil

headlight out and on the bench it looks like this




with the bulb removed and looking inside the headlight it was not any form of condensation and the silver reflective part around the body of the headlamp was still all nice and shiny.
tried a good polish on the outside of the glass but made no difference.
so has to be something on the inside of the glass.

using a tin of carb/ brake cleaner i sprayed it inside the headlight, gently so as not to get to much on the silver reflective part as i did not know how it would react with it.
as soon as i sprayed the glass, the fogging had gone and it was as clear as a new one, this is going to be an easy fix i thought.
so gently put a cloth inside to dry out the brake cleaner, all dried out and after 5 mins the fogging had returned just as before

but at least i knew it was something on the inside of the glass surface.

had a think about what to do.
(pictures below are after the fix but just to show what i am talking about)
re sprayed plenty of brake cleaner back into the headlight and put a small polishing cloth fully inside the headlight
and using a length of Kunifer brake pipe - which is bendy enough to make any shape yet strong enough to stay in shape, i rubbed the cloth onto the inside of the glass, concentrating on a small section of the glass




after a couple of mins of rubbing i dried the rest of the glass with the cloth, removed the cloth and waited for 15 mins.
sure enough the part i had rubbed with the cloth was a lot clearer than the rest of the headlight.

so to refine the cleaning i tie wrapped a few layers of cloth the the end of my brake pipe, sprayed that cloth with brake cleaner and went around the whole of the glass, which took about 20 mins max, re-applying brake cleaner to the cloth every 2-3 mins of rubbing and re bending the pipe to get at all parts of the glass


have to use firm'ish pressure when rubbing the glass, but it helps with the ridges that can be seen from the outside and felt on the inside of the glass to know where you are rubbing.
after i was happy with it i sprayed some glass cleaner inside and used another clean cloth + brake pipe to clean the glass and the silver reflective part.
then left it for 24 hours, before and after pictures below




no idea as to the how or why it happens but am happy with the repair, will report back over the coming months as to what, if anything happens to it again.
i should start charging for these repairs i am posting
cheers
Phil

Well done!! I posted my fogging story on TOS but never got a good resolution to the issue after trying a dozen different chemicals. I'll give the brake cleaner a go.

There used to be an excellent procedure for cleaning the inside surface of headlight lenses on the Woodypeck.com web site. I can no longer find it there, but it is very easy to perform, using white rice and vinegar. If you or anyone is interested and can't find it either, send me a private message and I'll forward my copy of it via return email.

woodypeck has posted here but with a different handle. I wanted to “at” him on this thread, but I can’t find any of his old posts.

Phil, Posted a report on how I did mine on the TIPEC website some years back.
Here's what I did to clear mine on MY88 S4.....

https://woodypeck.com/how-to-clean-your ... ight-lens/

Before and after shots



Hope this helps. Steve