The only other imperfection is also in the same pic, just along the bottom edge but there’s no crack and condensation could not drain out of it. There were roughly 50ml of water trapped inside the headlight, so on an extended drive all the moisture gets heated up and deposits to the lens as condensation. I think this crack happened when we first got the car back in early 2017 and it took all these years for that amount of moisture to build up. I don’t think any of the rainwater actually entered the housing directly. I believe moist air gets pulled in from there as the air inside the assembly gets heated up. Then, the moist air hits the cold lens during drive in a rain storm, forms condensation and this condensation ends up pooling on the bottom of the light (some inside the drive unit).
When I was baking the light, the lens fogged up when I took it out of the oven. When the light is sitting upright, the moisture couldn’t escape well even when there there was a roughly 2cm x 3xm opening at the bottom.
And here’s the update. I’ve got everything re-installed and working now.
The rusting drive module and wire harness:
First, I cleaned away the visible rusting on the connectors with Deoxit D5. Most went away without much effort.
Next, I poured rubbing alcohol into the bottom drive module, swished it around and drained it. Had to do this a few times until the alcohol draining was clear. Also took some time to rain all the alcohol out of it. I also set this alongside the light in the oven before re-installing it towards the end.
Opening the light
I could not open up the light – turns out it was sealed with permaseal glue instead of butyl and I didn’t want to cut it open… So, I opened enough on one corner, cleaned the dust/dirt/debris, filled the lens with distilled water via the opening to clean up some of the deposit on the lens and let the water drain out of the opening.
After I did that, I flipped the light upside down to let moisture escape via the bottom drive module opening and baked it at 225F for an hour to get rid of all the remaining moisture.
Took it out of the oven and watched for condensation. None happened, so I re-sealed the corner and added a layer of butyl on top of the entire seal to make sure nothing goes in.
I smeared a layer of epoxy on top of the cracked part, and also along the butyl to help hold it in place
Did a final check by baking it again standing upright to make sure no moisture was trapped when it was upside down…
Everything looked okay and reinstalled the light. I’d be happy if this works for another 4 years.