For the guides, you have to pull the valve covers and front cover. The front cover requires removal of the engine or a very capable mechanic. Used engines are almost always a hit and miss affair - no matter what the supplier says, The supplier gives you a limited short term warranty, so if not satisfied, pull the engine and ship it back at your expense - the next one may actually be better.
My advice would be to replace the timing chain/tensioner and upper guides (no need to pull front cover) and hope the lower guides are still good (usually are). If you have the chain noise, replace ASAP as a loose chain tends to chew up gears and variable timing actuators.

 

Are you sure it's a timing chain and not a balance shaft problem? Yeah.................of couse they're related

 

I am not sure. But, the M272s I have that have problems are well out of the problem range, 2008 and 2009. Any idea how to figure that out without removing the timing cover?

 

 

Yes, I've seen that video. I like the car wizard. I followed him since he started with Hoovies Garage. I prefer LegitStreetCars in that he actually shows the procedures and works on MBs while the wizard just talks about problems. As in this video, he tends to over emphasize the costs. I think it is insanity to own a MB out of factor warranty if you cannot work on the cars yourself. For me, this isn't a 3K to 5K job regardless of the route I take.

 

The parts prices for fixing the balance shaft aren't too bad, it's pulling the engine out to do the job that is rough. However, my understanding is that one can use an inspection scope to visually check the balance shaft sprocket, so you can determine if a timing chain replacement is sufficient.

 

Hi all I just happened upon the video below addressing this problem and thought I would share for the discussion

By the way the M276 engine does not have a balance shaft because it features a 60-degree V configuration, which eliminates the need for one, unlike its predecessor, the M272...

M276 Details Below

Mercedes-Benz M276 engine (2011-on) – Australian Car.Reviews

4 Common Mercedes M276 Engine Problems and Reliability

Learn about Mercedes M276 engine problems including the HPFP, carbon build-up, and timing chain tensioner. Is the M276 reliable?

8020automotive.com

 

my two cents is that i used to think i had a really bad timing chain/camshaft adjuster rattle on startup, however i replaced the 5$ oil intake tube seal, and all the noise went away. I have 251K miles.