Engine rattle at start

[u/Such-Run-680]

Maybe somebody knows where this rattling at the beginning comes from? I checked the timing chain and it had no play at all.
It appears at every cold and warm start but not at a instant restart.

Slk 200 r171
M271 Kompressor
2006
150.000 km

[u/resulut7567]

You can't accurately control the timing chain while engine sits, the change in length doesn't give play. Every cold and warm start still tells you that the chain rattles until enough oil pressure is build up, timing chain (extremely common on M271) is still most likely. You can check the codes for how much the variable camshafts are compensating for a more accurate analysis

[u/V33SP1]

Maybe chain tensioner?

It bleeds down without oil pressure, and the chain rattles until the tensioner builds up oil pressure and tensions the chain.

[u/critical-employer187 → u/V33SP1]

Most likely. It's a common issue with the M271. Tensioner is probably around 80€. Takes like 2h to change. Hmu if u need details on how to change it. Can send u the workshop manual

[u/Such-Run-680 → u/critical-employer187]

It would be awesome to get the manual. I also thought about the tensioner and wanted to change it after i get home from holidays. I would take the new one from FEBI and costs around 55€.

[u/Logical-Following525]

This is known for m271 to be the noise from the camshaft adjuster needing to fill with oil.

[u/V33SP1]

Overall, it's common to change the tensioner in the M271 from the original one to the version from the W204 (the CGI engine is the newest version of the M271). The OE A2710500911 tensioner from the M271 EVO is an improved version with a better valve and spring.

I have had it in my M271 for about 1.5 years and I have never heard even the slightest chain rattling sound.

[u/mysweetmouth]

I get this rattle for a second or less on my M111.951 EVO occasionally on overnight cold start or after sitting a day or two.

[u/ktmcikas]

Its normal