Hi I have had this problem since i bought the car, in both headlights of my 98 XK8..
I took the headlamps out and drilled the hole and fitted the breather pipe...Didnt make a difference..I took out the headlamps Christmas eve and sealed the holes i had drilled in the side...I noticed the front glass was actually coming away from the plastic of the headlight..Not the clip part but the actual glass.
I peeled the glass of and let the Lh headlight dry out naturally..The reflective part was still good on this lamp..The rh side was almost black as this problem must have been there for years...I wiped the residue of the reflective coating off and removed the bulbs..Cut some cardboard the same shape as the reflectors and masked them off...I bought some chrome spray paint from my local motor accessory shop and after a light rub down sprayed the inside of the headlight with the chrome paint..I have to say its not as good as the LHside but is very very presentable..I then used a clear silicon to seal and fix the glass back onto the front of the light unit...Re-fitted the headlights and then used a hosepipe high pressure on the lights without a drop of water getting in and it has rained constantly almost since then...No condensation and no moisture...
So if you have this problem i would have a very gentle pull on the glass part of your headlight before you start the hole drilling option as it will not work on a car with this particular fault..Hope this helps to keep your cats eyes clean.

 

Yeah - I read various fixes, but I just waited till they eventually dried out and then masked around the black plastic 'gasket' and carefully applied clear silicone sealer. A generic glue syringe would work well with bigger caulk-gun sized tubes of silicon. It worked! Apparently the seals got so sloppy they let in rain, and then allowed drying.

 

not a techie......can the glass be removed without removing the whole unit....i have one headlight that is all black inside....the chrome paint idea sounds like something I would like to try.....i keep looking at the headlamp but can't sem to understand the mechanic's of removal

Thanks for your response in advance

 

The glass and reflector are available as an assembly for ~$200....much less then an entire headlight replacement. See this thread and the thread it references:

https://www.jaguarforums.com/forum/x...mp-lens-72578/

This is probably the best price for new:
http://www.gaudinjaguarparts.com/par...w=11&maxRow=10

Chrome paint will never look as good as the factory chrome plating.

 

Thanks for letting us know that a inexpensive can of chrome spray paint isnt as good as the factory finish...However i would rather do it myself and be very happy with the result, than spend hundreds of pounds/dollars on new Headlights....Another tip is to ensure the headlights are not facing down....You can adjust the headlamps just above the radio...keep the setting on zero...This will help until you have time to take out the headlamp and re affix the glass properly...You can face the headlamps down if you want to have a gentle pull on the glass to see if this is your problem.....Several months have now passed and crystal clear glass is still there in this wet north west England climate..
Let me know how you have done with yours...The people who have thanked me in this post.

 

I was just trying to make the point that the lens/relectors are available separately for a lot less cost than an entire headlight if you do want to restore it to the original factory finish.

I am all for whatever makes folks happy.

 

This is the post I've been looking for! Thanks!!