The lacquer thinner reference was to okbarnett's proposed solution in that thread. I thought you were suggesting that. I don't think I skipped over any of the OP's posts. I am the OP
Anyway, today I will try the heat gun method to loosen the sealant and see what that brings. I need to rig up some kind of turntable arrangement so I can spin the light to avoid putting too much heat into one area.

 

Grab or borrow a Lazy Susan from someone's kitchen.

Following since I have encountered the same issue. I tend to agree with the assessment of it being a compromised seal. I am also in Florida (Tampa area - plenty of heat and humidity). In my case, one of my H4's had the fogging, while the other did not. Both bought at the same time. Also had the same issue with some sealed Cibie's - again, one fogged, the other not. (Hmmm, need to check if the same side fogged in both cases. Edit: for what it's worth - verified that my single fogged headlight in each 86.5 was on the passenger side!)

 

Well, I got one opened at last.

No amount of heat with the gun could touch the sealant. I had it on high, 2 inches from the join and it never softened. At least, not so I could remove the lens. No tool I tried could enter what I thought was a gap between the lens and the reflector.

My conclusion was that there is a mechanical seal as well as the butyl rubber which might only be a gasket, not a sealant. So I began to unpeel the rolled edge from the reflector. I sliced 1 inch sections all around the periphery of the lens so I could roll in back in small sections. With massive pliers, jewelers screwdrivers and a razor blade, it finally yielded:


Finally seperated. OoH Oh!!

Reflector coating peeled away

I don't know the cause of the peeling but I think the butyl adhered to coating and it pulled off as I separated the light. From what I can see, the coating that did not pull off is bubbled in other places, possibly from the heat I used in the early stages trying to separate the lens.

I've seen a thread on recoating the reflector with some kind of vapor deposit process but I can't find it now. Can anyone point me to it? It's that or new lights which may not hold up any better than these did.

 

Maybe this one?
https://rennlist.com/forums/928-foru...storation.html

 

^^^Yes, that's the one!

I need to check that out before I toss these and buy new. Thanks for spotting that.

 

I would shoot both sides of these lenses with urethane clear coat. Rough them up, spray the insides one day, then the outsides the following day.. once you get the other lens free of course. Or, send them to me, and I can spray them. Doing this should prevent them from ever fogging again.

 

After I got over the disappointment of how poorly the lens separated off the bowl, I took a closer look at the lens issue that started it all. I was wrong on several points about these lights. Firstly, the lens is glass, not a polycarbonate. Once I separated them, I tapped the lens with a small screwdriver and it pinged like glass, not a tick like plastic. Secondly, while I thought the lens was plastic and I could not wipe the haze off with direct pressure from reaching through the bulb opening with a swab soaked in ammonia, I was able to scrub it with a scotchbrite pad and soapy water and the film did start to come off the inside of the glass. With more effort and some cutting compound, it should come back to normal.

Which leads me to think there was some offgassing of some component inside the housing; either the LED bulb I installed or the residue off the factory components in the light (butyl gasket, reflector coating or the like). Whatever it was, I still think it reacted from the heat of the sun, not from use of the lights.

So my plan to coat the inside with a clear coat, and Austin's kind offer to do the same, might not solve the issue in the long run. Whatever I end up doing though, it will be a lot easier separating the lenses the next time, if I can keep them on in the first place.

I've reached out to Ghosteh to get the name of his vapor depositor so if I can salvage this set of lights, at least I will have laid a path for anyone that has to follow.

 

Yes, if the lenses are glass, then the clear coat idea is out. Oxidation of the lenses themselves is pretty much ruled out. Wishing you luck at procuring a solution to effectively clean them and to prevent recurrence.

 

What ever did that in the first place (I called gassing deposits)...a CC will be worse.

You will end up having to find a way to remove it...guaranteed.

Being this is the ONLY thread Ive every seen on this..I would reseal and carry on.

 

I absolutely agree. A clear coat on the inside of the glass will yellow, flake off, catch fire or worse. I have to get the reflector squared away before I can seal it back up so that means taking the other light apart so I can determine if I have to send both reflectors out for repair.

 

I had this on mine also, I got them clean by using a wire coat hanger with a cut up saucepan scrubber attached, was very had to get passed the lens deflector & took about 4 hours per light but did come up well

 

^^It seems this is more common than I thought.

I need something aggressive to clean my other headlight after seeing how tough the film was on my disassembled light. I'm thinking a bit of an SOS pad (fine steel wool with embedded soap for those outside the US) that I can manipulate with a flexible parts grabber. I may not be able to reach all the areas that have fogged, especially directly under the deflector as Callum_GT notes. But if I don't have to cut it open to clean it, that would be a plus.

 

Dirty lenses, yes, not what was seen here.

 

I am resurrecting this thread because I have resumed working on the fogging issue on these lights after setting it aside for a year.

After deciding that I really needed some lights on the car so I could get some use out of it, I bit the bullet and bought two more new H4 lights and resolved to keep the car covered when outside to prevent the same (presumably) sun damage to the new lights. After a year I am beginning to notice a very slight fogging in the new lights too even though the car has been covered for all but a few days in the interim. So now I have to find the solution because I can't keep putting new lights on the car every damn year.

I have come up with a way to easily defog the lights but it will all depend on just how important that light diffuser is in the center of the housing that blocks the incandescent bulb from shining directly forward through the lens. Since I am using LEDs with Ed Scherer's adapters, I don't see the necessity to maintain the diffuser in the center as the LSDs do not emit directly forward anyway. The diffuser is easily removable without removing the lens but removing it will require cutting it in pieces in situ, then removing the pieces through the bulb opening.

Is there a flaw in my thinking here or can I safely remove that diffuser?