CB Graves,

Not sure about your model, but many older Mercedes had the center vent only serve as either an A/C vent or a fresh air vent. They did not provide heated air. If it got cold you would just close them. I am not sure what the convention is with the newer cars, but I miss the blast of fresh air the old ones used to give out of the center vent. If you have a manual (owner's/operator's manual) this will be spelled out more or less clearly.

I am also not too familiar with the chain replacement philosophy, but unless you have a single row chain on that engine I would not expect to have to replace it at !00 kmiles. On the older cars the manual actually tells you to compensate for chain stretch by installing an offset Woodruff key in the camshaft/chain sprocket keyway. I think they come in 2 degree increments of offset, up to 8 or 10 degrees. I am sure someone will pipe up with more specifics on this subject for your car.

Good luck and sounds like a great car! Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)