BenzWorld Senior Member
Date registered: Jun 2011
Vehicle: 1999 E320 Sedan
Location: SF Bay Area
Mentioned: 0 Post(s)
Quoted: 54 Post(s)
It's always difficult to tell on a video, but in the beginning the noise is quite loud indeed. However, it seems that after 30 sec. or so it got much quieter--is this impression correct? Which begs the question: was this a cold start? Or had the engine been running before?
It's difficult for me to tell if the noise is rather of a chattering or of a chafing/clattering nature. The first would be more typical for the valve train/lifters, the latter for the chain. If this is indeed after a cold start, then it is conceivable that either the lifters are not lubricated well in the first moments or that the chain tensioner takes some time to build up pressure and tension the chain properly. Both these scenarios would explain why the noise disappears after a while, if, indeed, it does.
Also, which oil are you using? Have you recently changed it? Is there evidence of sludge in the engine? Especially the smaller, 2.6l M112 engines are reported to have a certain propensity for sludge build up, especially so at the top end. Have you ever taken the valve covers off? Unfortunately, on this engine you can't see much when you look into the oil filler tube.
But if I were you, I would first of all spend a few dollars on a "mechanic's stethoscope" and listen carefully to different parts of the engine (top end, front cover, with belt off). Chances are that this way you would get a much better idea of where the noise originates.