the lifters are hydraulic if I am not mistaken.

Mine does the same thing for a couple of seconds at first cold start. My mech and I have discussed it, and it appears when it has been sitting, they stick for a second until oil pressure builds up.

Not sure if this is the same issue you are having, but I am not too worried about it on mine as the sound goes away after a few seconds once my oil pressure is up.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon - Sold
2006 E350 Wagon - 368 - Dead
2015 GL350 Bluetec - 197U