1997 E39 bmw 540i headlight lens
 

my old bmw has a very big and quite ugly build up of old stained in moisture, and i was wondering how i can remove the lens to hand clean the build up out. does any know how to remove it easily without damage?:rolleyes:

I saw a DIY at bavauto.com a long time back. Early E39s had bad seal. You can also consider getting the E39 angel eye lights from bavauto.com as the bad seal will cause problem again.

I would upgrade the lighting on that E39 to the Angel Eye/Xenon model in the later E39 series.

Here is the exact link you need
BMW E39 Non-CELIS Head Light Removal & Lens Cover Relacement
But it seems you mean reflector,not lense
The cover glass becomes foggy from grit and rock chips also, and there are a couple of DIYs for that. Or do you mena the projector lense of xenon lights?
anyway, that linkd describes the removal, check e46fanatics.com for lens polishing
If your relectors are bad, salvage or aftermarket is good but converting to xenon is fairly expensive,assuming you do it correctly and use a projector xenon housing, even if you don't add the whole self leveling feature