Hate to be a wet blanket, but you haven't discovered how the air got in there to begin with, as far as I can tell.

These cars have a tank vent that runs to the right rear corner of the car, under the bumper trim. If you pull the plastic liner away on that side of the trunk you can find the vacuum lines that run from the tank to a little "settling" tank and from their to the hole in the right rear corner of the car.

When this thing gets wet with fuel from over filling, typically, the rubber connectors get gooey and they can close off. When that happens you can be driving along and all of the sudden you stall. The engine stalls and won't restart. You can't "prime" the system because it can't pass fuel from the tank to the injection pump. You opened the system which should have made this possibility go away. But, typically when this event occurs it is really difficult to get the fuel filler cap off. And sometimes the fuel level gauge goes nuts.

My point is, I don't see what caused your original problem. So, I would be concerned you will be at the side of the road again, stalled and unable to get going. Jim

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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)