190e Chain tensioner question
 

I have just replaced the rails and tensioner on my 190E 2.3. I have a slight whir when the engines running its coming from the top left tensioner rail where the chain tensioner pushes against it, now the car had done 110,00 miles so maybe the new noise is as it should be. But after all the work to do all this I want it to be right. I did remove the tensioner a genuine MB part check it an replace it being very careful to ensure it was inserted and then only tightened to 15NM the recommended toque before putting the hex cap on.

This tensioner is not adjustable you just put it in tighten to the correct torque but the spring in and the hex cap on an torque the hex cap up. Is a little noise normal difficult to describe sounds bit like a sewing machine. As I have checked and double checked the torques etc and used genuine parts not sure what else to do.