The other possibility is a torque converter that leaks down. There isn't enough room in the case for all the oil in the converter, so it spills out the top vent. Big mess, eventually happens to any MB that sits for a long time, but usually takes months, not hours.

Does it pull immediately when you start it and put it in gear, or does it take a while to start going? If so, torque converter is draining down. Bad news, this is both a pain and expensive.

Otherwise, can you see where it comes from? Could be a leak on the side somewhere that only lets fluid out when the guts drain down.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!