my e320 wagon's engine is making some kind of valve noise or like a rocker arm. I have already had it check somehow all the diagnosis was wrong. It's still there ( the noise ). An experienced shop mechanic working for a small shop that takes all kind of cars told me that it was the piston pin that is noisy. is that possible since the engine runs good except for the noise ?? Is there anyone who's got the the same problem help me with these ??