I have a very similar problem with my 1988 190D. I personally never
touched the lines, as I'm waiting for a manual. However, it does leak
on occasion, esp. after my alternator died and I let the car sit a day
or two until I got the new one on. The leaking has completely stopped
since, for now. It did leak on occasion before, enough to leave
silver dollar-sized stain on the driveway overnight. At other times,
the leak seems to be gone. It doesn't seem to matter if I have a full
tank or near-empty, but I plan to pay closer attention.
I know nothing about this car's history, except that it wasn't taken
care of very well. It had pet stains all on the carpeting that I had
to yank out and sanitize. The nice oversized chrome rims have a few
dings on them, and there is a buffed-over swipe on the passenger rear
quarter panel, with stress fractures on the tail light housing. We
joke that this car must've been a getaway vehicle at some point. There
are miles of monster cable and screw holes from prior amplifiers and
speaker boxes in the trunk. Grandma did not own this car.
Click to see the full signature.