Here’s the symptom: headlights aim too low. There are two brittle plastic parts inside the headlight assembly that must be replaced to properly aim the headlights. Getting inside the headlight assembly is non-trivial.
First, remove the headlights from the car as follow. Watch this video from 4DIYers YouTube Channel https://www.youtube.com/channel/UCXFTtJnIaE68Oh0TPvasczQ (many thanks, it helped me with my 2003 E39 M5):
Published on May 23, 2014
Video tutorial on how to remove the headlight assembly on a BMW E39. This procedure applies to the pre-facelift version found between the years 1996 and 2000, but the similar procedure can be applies to the facelifted version 2001 to 2000. This particular tutorial was done on a 1997 BMW 540i.
I used a Torx T-15 to unscrew the lower bolts because the magnetic thingie on my screwdriver made it easy to retrieve the bolt since you can’t easily flip the car upside down and shake the bolt out.
Headlight Disassembly and Cleaning
I set up shop in my office inside where I have air conditioned room to beat the 100+ deg F Summer heat in the garage. Before removing too many parts from the headlight assembly, I sprayed a damp shop rag with 409 cleaner, and cleaned all exposed surfaces.
Instead of replacing the brittle plastic adjusters with the same part, I ordered aluminum ones (thanks, Charles T.) for both sides:
CA Automotive Aluminum Head-Light Adjuster Repair Kit for the BMW 5-series (E39) 10/00-03
Next, I removed as many parts as necessary, and thoroughly cleaned all surface areas.
Notice the brittle plastic pieces pictured next to the new ones at base of lamp that you have to carefully shake out of the headlight assembly. I also took the disassembled headlight out to the garage, and hit it with 100 psi from my air compressor to blow out as much particulate matter as possible as a final step before reassembly.
Even though I read on the forums about the 2003 BMW E39 M5 having “permaseal” no-bake lenses, I tried the bake method to no avail. I started at 150 deg F for 20 minutes, couldn’t separate the lens from the chassis, tried 250 deg F, and decided that BMW, indeed, changed from a butyl seal to a non-butyl seal (epoxy?) that could not be easily separated.
The next step is to install new adjusters. Getting to them is very much non trivial. Here’s a good headlight disassembly video:
Here are photos that show the alignment of the new adjusters with respect to chassis.
Sorry for the hairy leg shot.
For one adjuster, I was able to use forceps to maneuver it place after picking out/unscrewing all remnants of the old brittle plastic adjusters. The following video helped me out immensely:
E39 Xenon Headlight Adjuster Replacement No Cut No Bake
Unfortunately, I was unable to perform the procedure for the other adjuster, got out my Dremel tool, performed invasive surgery, and followed steps from the following article:
Through that hole I cut, I was able to remove one of the plastic adjuster bases from the chassis, manipulate the new adjuster into chassis, and install the plastic adjuster base back into the chassis yet not snapping it onto new adjuster just yet.
Plastic Adjuster Base:
New Adjuster (I had followed instructions elsewhere to snap plastic base onto adjuster before installing new adjuster yet ran into a problem with mechanical interference that required me to unsnap it and then re-snap it along with the other one at the same time).
New Adjuster after Installation:
Angle of Attack to Reach Screw on Adjuster Base:
To access the screw on the adjuster base, I had to buy another Torx T-15 screwdriver without the magnetic shroud that was too large to fit through the angel eyes aperture. I used duct tape to hold the screw onto the screwdriver.
New Adjuster and Old Base Installed:
Adjusters Snapped into Bases at Same Time (wait until *after* you position actuator):
It was necessary for me to manipulate the inner headlight assembly in order to re-install the actuator and to slip ball end of actuator onto the actuator receptacle.
Receptacle for Actuator:
The other headlight went more smooth than the first one. Here are some photos of details for it.
Adjuster with Respect to Chassis:
Use of Forceps to Install Adjuster:
Adjuster Held in Place with Forceps:
Access to Screw on Adjuster Base through Angel Eyes Aperture:
Duct Tape to Hold Screw:
Forceps to Insert Base:
Forceps to Install Other Base:
Duct Tape to Seal Chassis:
Yes, I used duct tape to repair my BMW. No judgement.
Angel Eyes tested and working:
Low Beams tested and working:
High Beam tested and working:
Lights Off Daylight view:
Polishing the Lens
I opted *not* to polish my lens yet wanted to share a great article from the M5 Board about the process that I may go back and do later in life:
You have to love it to do it. I drove home last night in the dark and appreciated the working headlights. More importantly, I appreciate getting my hands dirty with German engineering and having the opportunity to learn something new. Enjoy. Your mileage may vary.