Dreyk2000

Hey folks. Here is my issue. Maybe someone already has it before. When start the engine at cold start everything is normal no abnormal sounds or anything like that as soon as engine reaches work temperature from passenger side head start hearing knocking sound. Sound comes from exhaust cam. My engine already have fixed timing from manufacturer. Steps I've done already: Removed oil pan to inspect for any debris or metal shavings etc. Pan is clean inside like almost new. While pan was off with endoscope checked the timing sprokets and guides and all looks good no issues. Next i removed vavle cover to change followers and rocker arms on exhaust camshaft and to inspect camshaft itself and camshaft seats. All in great condition didn't see anything abnormal. After those repairs same sound and only when the engine is hot. No check engine light whatsoever. I have StarDiagnostics as well. Next step i will try to replace VVT sproker on exhaust cam with oil control valve otherwise i don't know what to do. I will appreciate any suggestions.

E55Greasemonkey

Every m272 V6 engine, which is just the 6 cylinder version of your engine, makes this sound. If it is in fact the same sound, it's normal and there's nothing you can do to fix it. Read here:
https://mbworld.org/forums/mercedes-tech-talk/851142-m272-one-cam-position-erratic.html#post8771001

Dreyk2000

My engine M273 V8

E55Greasemonkey

Yes, it's the same engine with 2 more cylinders and an idler gear instead of a balance shaft due to the even number of cylinders.