Hi Marco,
Indeed take it as compliment

my grandfather was italian, even teach me language when I was a kid
I was never able to speak it fluently but when I am in Italy I am still able to do the basic communication

As you wrote „back to business“
I will try to explain things in Detail as I played with them a lot:
There are two types of chain tensioners out of those five models during 16v Production
1. without deadlock (all other)
2. with deadlock (Evo2 and one of 2.3-16 tensioners)
Mercedes itself was in doubt what to do - it is the reason behind five tensioners
All have spring inside, housing in which is a spring and piston or pin (I don’t know how to call it correctly) in the middle
Screw that you pictured is for releasing the spring tension on those without deadlock
On those with deadlock you need to unscrew complete housing to free tension from chain that one big screw is not enough and if I remember it is Imbus inside not screw outside on an Evo2
BUT that spring is not enough for tension of chain, is there more like to keep tensioner pin in place before oil pressure is reached in first seconds after engine is started and tensioner is properly stretched
This is why some 16v cars have loosen chain sound in first seconds after start Those without deadlock operate on oil pressure ONLY to make chain stretched by pressing the guide and should press longer way inside as chain gets longer from normal operation and mileage driven
Housings of tensioners with a deadlock inside are machined in zig-zag shape inside and have a ring that make central pin travelling possible in ONE DIRECTION only (in direction longer = towards chain) they also work on oil pressure but the most important - CAN NEVER GO BACK inside engine. They also self-adjust for wear in guides and chain streching over time by clicking in next longer position. Outside engine man can make them short again by pressing pin out and then installing it again on start position. IMPORTANT this is the only way to install it once removed (making it short), installing long deadlock tensioner leads to instant engine damage !!!
For 2.3-16 they all work correctly as long chain is not over 70.000km because chain is ligh and is easy to tighten it
Therefore I wrote
don’t worry about it you have 2.3-16v with single chain BUT in 2.5-16 it is problematic because chain is heavier (duplex chain) and much stiffer before engine builds oil pressure in first seconds after start it is still not tightened and it can snap (but never break) just jumps and tends to break valve cover from inside rarely it springs on next teeth of cam sproket
This happens even more often on thick oil and cold temperatures so is the best to replace it with Evo2 type on 2.5-16 engines
However Mercedes never again installed such long chains as 16v - it proved a bad engine design. Now they do short chains to only one cam sprocket and then control the other via gear mechanism.
PS At time of 190 production I think Bilstein was one company, I think Febi Brand emerged later out of Bilstein because for example SLS accumulators were back then Bilstein today is Febi only and Bilstein accumulator today doesn’t exist
Bye
Nikola