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How-To: Quad LED Projectors Retrofit into W166 Halogen Headlights
TLDR: the project is a real PITA, but the result, IMO, is well worth the effort. Total cost is just under $600 CAD (appx $450 USD). Great light output. No error messages. No CANBUS module required.
Hello All,
Long time lurker, first-time poster on the MBWorld board.
When I was upgrading from the 2009 W164 ML to the 2012 W166 ML, I simply took it for granted that a vehicle of this level would've come standard with some decent headlights. Oof, was I wrong... My car came with the underwhelming halogen projector headlights, and as many of you have already experienced, they do not perform well at night. Living in Canada means my commute in the long winter months takes place in the dark. This has prompted me to look into some headlight upgrade options. The MB intelligent lighting system upgrade is simply too expensive. Installing HID or LED in halogen housings or projectors never looks right to me. So I've decided to bite the bullet and do a full retrofit upgrade.
I did a lot of research before ordering the parts. I did not find much information about these W166 headlights. So I hope this how-to helps anyone who wishes to upgrade their W166 headlights, with either LED or HID projectors. Or... it helps you to decide not pursuing this route.
Parts list:
Moshimoto M LED 2.0 bi-LED projectors x 1 pair
Moshimoto Mini HB projectors x 1 pair
High beam splitter (H7 Male > H7/9006 Female) x 1 pair
Mini Gatling gun shroud x 1 pair
Butyl x 1 roll
M5x25 bolt x 8
M5 nylon locking nut x 8
3/8" washer x 16
Paint pen or marker pen
Shop-vac and compressed air
Tools required:
Hydraulic jack and jack stands
8mm and 10mm sockets
Heat gun
Oven
Trim and plastic clip removal tool kit (Amazon)
Pick kit
Dremel tool with various attachments
Torx screwdrivers
Flat head screwdrivers
Step 1: Remove your front bumper. Refer to this guide from Mercedes:
Step 2: Remove the headlights along with their supporting brackets. I forgot to take photos of this step, but it is straightforward.
1 long 10mm bolt up top, along with the two plastic tabs you can turn with a flat head screwdriver. 2 10mm bolts next to the radiator support. 1 10mm bolt in the back buried inside the fenders. There is also a plastic piece that connects the headlight support bracket to the front bumper beam, 3 10mm bolts on that piece. On the driver's side, this piece comes off easier if you temporarily remove the 2 10mm bolts holding the windshield washer fluid bottle in place. Be careful pulling away the support bracket and the headlight, there is a plastic tab near the radiator support, and another tab inside the fender. Try not to break these tabs. Now you can take off the 2 10mm bolts holding the headlight housing to the support bracket.
Step 3: This is perhaps the most time-consuming part of this project... Mercedes uses Permaseal to hold the lens and the housing together. Heat only makes Permaseal softens up a little, but it doesn't melt and pull apart like butyl does. This means you will have to use a lot of patience and swear words to separate the lens and the housing, there is just no other way around it. I used my heat gun to heat up a few inches of the seam at a time, and pried the black plastic back to expose the Permaseal. Then I used a 90* pick to get inside the lens to break the seal. You will find that it's nearly impossible to get a tool inside the crack to break the seal at some spots. After you break loose as much as you can, use the clip removal pliers to separate the housing and the lens while heating up these difficult areas, it'll pop open.
The first headlight took me 3 evenings to figure out how to open it.. The second one only took about 2 hours.
Step 4: undo all the Torx screws and disassemble as much of the headlight as you can. You'll end up with something like this:
OEM projector vs Mishimoto MLED 2.0
Step 5: Now is a good time to clean off all the remaining Permaseal from the lens and the housing. Just use the heat gun to soften the Permaseal and use a blade or flat head screwdriver to scrape it off. When the plastic is still soft and hot, bend it back to U shaped channel.
Step 6: Now we modify the low beam projector bracket. Since the MLED 2.0 is quite a bit shorter than the factory projector, I've decided to mount it to the front of the bracket, so that the projector lens is not recessed back. There is a little bit of clearancing we need to do. The goal is to be able to mount the metal plate flush against the plastic bracket. Make sure to cut a little more than "just fit" in either direction, so you have some room to clock the projector. The four little plastic pillars where the stock projector is mounted to need to be cut off flush. Warning: this step is the point of no return.
Step 7: I forgot to take photos of this step... Now we use the four mounting holes on the metal plate to fasten the MLED assembly to the low beam bracket. From front to back, here is the order I used: M5x25mm bolt through metal plate, washer, plastic bracket, washer, nut. Test fit and "dry assemble" a couple times. You may need to enlarge the holes on the metal plate a bit, and you may need to clearance the plastic bracket a bit to allow the bolts to go in straight.
Step 8: We will use the threaded shaft to mount the Mini HB to the high beam reflector bowl. The H7 lightbulb hole needs to be enlarged slightly. The reflector bowl needs to be trimmed between 8 o'clock and 4 o'clock to allow the Mini HB assembly to be mounted flush. I cut off pretty much all of the coin edge portions. Now you should be able to put the threaded shaft through, install the H7 adaptor ring that came in the box, and screw on the nut.
Step 9: Install the shrouds onto the projectors. The stock low beam shroud fits the MLED perfectly with minor modifications. You only need to trim off the tabs at the bottom, and grind off the clips at 3 and 9 o'clock a little bit. The mini gatling gun shroud needs to be trimmed about 1/2 inch shorter so the front sits flush. I used 4 drywall screws to hold the shroud and the Mini HB together.
Step 10: Test fit the shiny bezel piece. A little bit of trimming is required to fit around the shrouds.
Step 11: Connect up the LED driver and the harness. Now you can test and align these lights. Tip: the H7 connector plugs into the Milwaukee M12 power tool battery, so you can fire up these headlights anywhere. Temporarily re-install the headlights and clock the projectors so the light patterns are level. Mark the final positions with a white paint pen. It is a good idea to mount the headlight housings onto the car WITH the lower support brackets, so it simulates the final mounting position. I learnt this the hard way, as I found out the brackets do move the headlights a couple of degrees. As a result, my low beams are a little crooked.
Step 12: Take everything apart, and clean the plastic shavings and fingerprints off all the parts. Now you can do the final assembly. Wear rubber gloves so you don't leave fingerprints inside the headlights. Apply the butyl rubber into the U channel and bake your lens and housing sealed. There are plenty of instructions on YouTube about re-sealing the headlights.
Step 13: Re-install your headlights and the front bumper cover.
Let's be honest, most of you only came in to see the results, so here it is. Notice the low beam cut off lines are a little crooked in the wall photo due to the mistake I made in step 11. Thankfully, this is the only scenario where it is noticeable.
Low beam:
High beam:
Conclusion: it's a lot of work, mostly due to the Permaseal. But I think the result is quite worth it. The lights are very bright, and the light pattern is very even and usable. The high beam adjustment screws are temper proof with 5 edges, I will need to find the special socket to align the Mini HB's . So I expect the high beam performance to get even better.
12-24-2020, 08:39 PM
How-To: Quad LED Projectors Retrofit into W166 Halogen Headlights
