So I kind of been noticing rough engine sound but can't really tell because I'm so use to my car's sound, idle is stable. I recorded a video of my engine working, could you compare it to yours m271 sound and let me know if it sounds OK or not?

Thank you for your input.

 

It's not like mine. Yours has a high pitched noise that's not right.
I suggest as a first step you remove the ribbed belt, run the engine briefly and see if it goes away. If it does then check all the pulleys etc for bearing failure. If it does not go away then remove the cam cover and check the timing chain.

 

What is the mileage? It may be timing chain issue.

 

Mileage is 102000 miles. I opened cam box at 93k to check the chain and it was normal, teeth on vanos was ok and chain stretch was 5 degrees which is normal for this mileage. I talked to a couple mb mechanics and they both said that critical stretch is 9 degrees or more.



Will take the belt off and see how it sounds..