I say you've got a big set of ballz to take on this job, period.
I rebuilt my first engine at age 15. Been dicking with cars my whole life. My latest claim to fame was back in 2006, when I swapped a crate engine 502/502 big block into my 1997 Safari AWD. Swapped in a 4L80E tranny, custom 9" rear and a transfer case from a full-size pick-up. Then took that #hit on a two week trip throughout the southern US, just to prove that the setup was reliable.

When I pop the hood on our ML, the hair on my neck stands up. I wouldn't dare do any major wrenching on this thing. You sir, have a big set on you.....

 

ML has easier access to the engine. When I was replacing OM642 in sedan - took me 2 days just to disconnect wires from the sensors. Down the road I figured out that I could easy pull the plug from ECU and pull the engine out with harness on it, when pulling the plugs on engine outside would take 1 hr instead of 2 days.
On the end I had 3 brackets I could not find the place for. But thanks to the google, I search for part number (stamped on each MB part) and that gave me placement.
That is still nothing comparing to making my home weather station staying connected to WI-FI. At least I figured out WI-FI thermostats.

 

I find all the placements from EPC. That even includes the correct bolt size. I tried to label all bolts when I took them out, but I still couldn't figure out some of them at the end so I used EPC to identify their locations. I got the cloned EPC/WIS/ASRA from ebay for only $8. I'm not sure about yours as it's an older model, but the harness connectors on mine only took me about an hour to disconnect all and I basically just flipped the frame of the harness towards the front that gave enough clearance to continue working. It's a little difficult to work on those bolts on the back side of the engine, but there are only 16 bolts including 14 for the turbo and 2 for the crankcase breather. I know it's probably more difficult to remove these bolts on a sedan.

 

First, thanks to the OP first posting pics- they are the first 2014+ om642 pics I've been able to find.
just did the oil cooler seals on my 08 gl320, about to do it again (almost) because I have a leak at the connector pipe between manifolds. I also didnt tighten the egr cooler lines at the back adequately!
I've acquired a gt2260 turbo from a European car. The headache is getting the water cooling hooked up. I have the later style turbo mount with water passages and your pics finally answered my question about the coolant feed- indeed the block casting is different! I will do as at least one other and tap the side of the mount to feed in coolant (and block the bottom).
for the drain- had a quick look at a 2015gl today and it looks like the line off the top of the turbo, coolant return, goes either down to the block, or to the intake manifold.
can you confirm? Easiest is to hack the return line and run a hose back to the reservoir, but since I'm pulling the intake again anyway, thought I'd check if sourcing a later manifold would be cleaner way, or even drilling the current manifold for the return line.
cheers, hope it is still running well!

 

Thank you for the LM Intake Cleaner information!

I just phoned our local Napa store and they took my order for three cans, but they phoned back 10 minutes later and said they are unable to get it shipped to their store!
No reason why, just cannot get it shipped?

Strange.

I would have sprayed some of it on my 2008 W211 642.920 just as a preventative measure.

 

FWIW the method I used of cleaning the intake manifolds was the burn-it-with-fire method. Really fast and effective. Obviously must be done outdoors. All the plastic parts related to swirl flap linkage are on the outside of the manifold, so they're safe. This is easier/faster/less messy than any liquid solvents and manual scraping.


Totally cleaned out:

 

LOL, now there's a novel approach

 

^^+++