I have a new 1999 E320 that rattles after start up. I assume its the hydralic valve train doing the rattleing, and is this normal? I drive the car on long trips, and it sits a few weeks at times before it driven. When started , it rattlesw a few seconds and then quiets down. Still this engine is a little clickie in the valve train even at that. Once you start it, it's fine until it sits a week or so. Any ML320 or E320 drivers noting this problem (if it really is ine at all)?