Lou275

When I got my car 4 months ago the electronic trunk could barely open, close, and lock. Now it all works flawlessly.

This mechanism at the time was an option, and as many already know not the most reliable one (often only after 3 years of possession of the car one or more of the issues I have described and resolved below are present).

(Note: this topic may help with W220 and C215/W215. Mind that it will not help if you have an issue with the default (non-electronic) trunk mechanism, which from the outset uses telescopic springs and not gas-operated springs. Always double check the part numbers, I might have made a mistake. You can find some supportive instructions here)

At MB they told me that the right gas-operated spring had to be replaced and all will be fine. I obviously did not believe it and did a little research on the matter and some inspection myself and found that the following had to be replaced:

1. Right hinge: it was rusted and slightly bent. I got a left and right from white CL55 AMG 2003 and repainted in 747 (the color of the car). (Mind that the hinges from a non-electronic trunk are not the same.) [ left: 2157500587 right: А2157500687 ]
2. Right and left gas-operated springs: both were very very weak so I got two brand new. [ left: A2157500336 right: A2157500436 ]
3. Hydraulic pump motor cylinder (see here as I could not find an image of it): it was totally busted and was leaking oil so I got a replacement from a fairly well preserved pre-facelift CL600. [ A2158000148 ]
4. Full boot locking mechanism (excl. the lock cylinder): [ A2208000478 ]
   mine had in general three issues:
   a) Cracked and broken rear trunk latch actuator: when I got the replacement mechanism, it was also cracked (not broken) but I fixed it with a lot of silicone see (4. a - fix) below. I have also added on top a ziptie later for good measure. Keep in mind that the idea here is not to simply strengthen this component, if you do so with glue or just zipties it may also not last for too long as the old plastic and other components may also be unable to handle the pressure. What you aim to do here is to enable a degree of flexibility - the silicon will stretch slightly and then revert over long periods of time, meaning that it will take some of this specific pressure load on itself rather than on the rest of the system and the system will last much longer this way. [ A2208000275 ]
   b) Small cracks around the openings where the air enters and exits: they were really minor and perhaps were not an issue, but I covered around them with silicon nonetheless. Be careful not to put silicon close to the metal bead because it will get stuck and air may not be able to enter or exit. See (4. b) below.
   c) The spring in the lock mechanism was totally destroyed: the spring was basically missing and the lock was flapping around. I just replaced the entire mechanism with the replacement one, where the lock was in great condition.

I don't have a video of how everything can be replaced, however, there is plenty out there and it is fairly straightforward. A few more things that have to be considered on the way:

1. Points 1-3 above solve the opening and closing, while 4 solves the locking issues.
2. Be careful when replacing the hinge, you need to make sure that the trunk closes all the way down, otherwise it will likely not lock.
3. Remove everything towards reaching these components as these cars are quite old and most of the plastic is very fragile - now these cars can over 20 years old, so proceed with caution.
4. When removing some of these plastic pipes (e.g. item 20 in image (4) below) be very careful as they are tight and at the same time the holders can crack, bend, or brake.
5. Place component 100 from image (4) below correctly (at the same distance as the original one).
6. Ensure the lock is in the same position as the original one, otherwise it will not lock.
7. Apologies for the lack of many images, however most of the things are quite easy.

(1) Hinge and (2) springs


(4) Full boot locking mechanism


(4. a) Cracked rear trunk latch actuator


(4. a - fix) Two days after it was covered in silicone, it was ready to be installed. All cracks were covered well and the space between the cap and the body was fully sealed.


(4. b) Openings with beads that control air intake and release to create pressure. Watch carefully and more often than not you will see cracks, which I eventually filled with silicone. Be careful not to put silicon close to the metal bead because it will get stuck and air may not be able to enter or exit.


(4. c) The lock (part of the entire mechanism). Ensure that it doesn't flap freely.


5. Just an image of the opened system - checking the replacement and the original - absolutely identical despite one being from 2001 S600 and another from 2004 CL600. You may need 2 people to work on this otherwise the risk of damaging something is higher.

mbwillgrubs

Nicely done. Write-ups like these give people confidence in their ability to repair these cars without going broke. I had to repair a broken air fitting on my seat bladder and just used gasket maker. Let it set and viola. Thanks for taking the time to post.

Lou275

You are right, all of the items didn't cost all that much and keep in mind that the trunk lid is fully operational.

An approximate breakdown is as follows:

1. Right hinge: ~$18, I got both left and right from Russia where they import lots of these cars from Japan at often sub-100,000 KM milage and disassemble on parts - you can find pretty much anything on Avito
2. Gas-operated springs: $77, for both, brand new.
3. Hydraulic pump motor cylinder: $47, sourced it locally from a scrapyard with online store.
4. Full boot locking mechanism: $64, again from Russia.
5. Silicon and some duct-tape: $2

Total: US$208 for the parts and all the work required around 2.5 hours for me because I am rather new to this and it's my first car.
The idea behind buying well-preserved used parts for these old cars is that you don't have to wait forever for them to be delivered. On my trip to Russia I got 1 and 4 in my luggage and the pump I got the same day I called the scrapyard. Had to wait nearly 3 weeks for the springs.