I have owned my 1999 E39 2.8 BMW from new and its 165,000 miles have been completed with few faults. It is still a great car.
Of late however the headlights have been suffering from condensation between the plastic outer cover and the bulb / reflector inners. I have removed, dismantled, cleaned and dried both units.
To start with they looked good but the condensation quickly returned. I don?t understand why - when dismantling the units, they appeared to be vented at the rear into the engine bay.
On 5th June 2008 TomH reported the same problem on this Honest John E39 Thread ? however there was no indication whether the problem was solved.
Can anyone advise? Do I have to install new headlamps? They sure don?t come cheap!
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Having posed this problem 3 weeks ago ? felt I should now report back the solution.
I removed the headlamps again following the instructions in the Haynes Manual ? one of the lower securing bolts had seized and needed drilling out using an extension piece to gain access. Replacement bolt from BMW as part number B07.11.9.916.980.
Once off the car the water was literally poured from each headlamp !
The units comprise the front housing of transparent plastic mounted on a black plastic surround. This carries the glass lenses. The back housing in black plastic carries the reflectors, bulbs and beam levelling mechanism.
The rubber seal on top of the headlamp was removed by releasing three plastic clips.
The front and back headlamp housings were separated by releasing the plastic clips all round the join. The glass lenses were then removed by tapping off the four spring clips with a light hammer and long masonry nail. The residual water that hadn?t already been removed was poured off.
The joint between the transparent and black plastic sections of the front housing was thoroughly cleaned using a nail brush. The inner face of the transparent plastic was cleaned through the holes exposed by removing the glass lenses. Both sections were thoroughly dried using a hairdryer on low heat - water in the yellow indicator section took quite some time to blow out.
Silicone sealant was then applied to the joint between the transparent and black plastic sections of the front housing. It seemed likely that after years of use this joint failed and water entered by capillary action. N.B. the silicone gives off reaction water (dilute acetic) during setting that shouldn?t be sealed in. Once set, the cleaned glass lenses were reinserted.
The rubber gasket that sits between the two housings was replaced (BMW part number B63.12.8.362.446) and the two parts rejoined ensuring that all the clips were secure. The new gasket meant that rejoining needed quite some compression force.
The top rubber seal was refitted and the units reinstalled to the car greasing the bottom trim / seal.
The outer transparent plastic sections had small stone pits and I spent 1 hour polishing each with T-Cut. This markedly improved their transparency and appearance.
So there it is ? early days yet but after several torrential showers all seems ok.
Misty Eyes to Bright Eyes !
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