I bought a MightyVac this weekend and can see where this will be a very handy tool indeed. The tool confirms that the white (clear) tubing is the one that is leaking. After deeper investigation in the passenger footwell, the MightyVac found the culprit to be the Grey/Green tubing connected to port 5 of the distribution block. Fully plugging that port corrects the problem. Now all I need to know is what is on the other end of that grey/green tube! Anyone with some in-depth info?

__________________
1996 SL320 97K miles
1996 C220 130k miles
1992 500SEL 170k miles <---sold
1986 300E 216k miles <---sold