I have a '71 220D with a mystery vacuum tap on the main line between vacuum pump and power brake booster.
It's unconnected, and there's also a disconnected hard line up by the firewall, but it doesn't have the length to connect to the brake-line tap. (These are the only vacuum fittings on the car.) That line is split by some sort of check valve or diaphragm/filter, and it disappears under the driver's side fender, right under the windshield corner. It's green, and it doesn't seem to reappear under the dash.
I thought at first it had something to do with the windshield-washer pump, but that's foot-operated, and I've successfully reconnected that.
Any idea on what the mystery line/tap is? I've got some MercedesSource hard line and fittings to reconnect things, but how and what?
(Auto transmission car has no power locks, no AC, no vacuum shut-off of IP -- that's just the straight wire from the push-pull dash knob.)
Thanks in advance!