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Coolant leak from right return line / can't find correct part

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Old Jan 25, 2022 | 12:07 PM
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2012 e550 coupe c207
Coolant leak from right return line / can't find correct part

Hey y'all,

I got a leak coming from the right turbo return line right on the water pump. Haven't really pulled anything out yet so pretty cramped but I'm running into a problem. 2012 e550 c207 m278.




Here you can see the leak pretty clearly off the return line coming into the water pump. However looking at WIS it's showing incorrect data for my car...





According to WIS part 17 is the replacement hose for it however that's incorrect. From the first picture it doesnt have the big block piece coming off the back of it and it's not merging into another return line...



Part 80 and 90 on this diagram. I think this is for newer engines I'm not certain. Saw a video of a 2015 and the diagram looks corrector for it with the big blocky return line:



finally my return line that is leaking doesn't have that coupler that the second feed like sungs into the back on the other side of the water pump... Just a small rubber hose going into a metal one. I've traced it and it goes all the way to the turbo as on piece. Last pic is of the line sticking out in front of the water pump pulley


Know I'm rambling a lot but I think I found a part number on some Russian website that seems to look like a match visually... 278-200-12-51. Ive checked a few Mercedes service department websites and they all are saying it's a discontinued part. I can probably get one from some random shop in Europe but I first wanted to confirm this was the correct part number and two figure out if this is the correct fix moving forward, or should I be buying that new style of blocky coolant line and a bunch of other lines and reroute everything?

Sorry for the long post but really would appreciate some help from a 278 wizard! Thanks for reading this far!
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Old Jan 25, 2022 | 01:54 PM
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Old Jan 25, 2022 | 02:07 PM
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2012 e550 coupe c207
Originally Posted by konigstiger
Post VIN.
WDDKJ7DB8CF149354
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Old Jan 25, 2022 | 02:20 PM
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No wizard, EPC shows right return line (50) is part # 2782000851.



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Old Jan 25, 2022 | 02:28 PM
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Hmm might have just been looking at the wrong part and got scared by the diagram. Says its for a 4matic but looking at pictures of the actual part, it looks correct. Worth a shot, appreciate your help with this one! Thank you very much!
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