One hell of advise here. I had a leak recently on the A/C system.
A W124. You think it has nothing to see with your problem ?
Read this : in the garage the leak was spotted on the radiator of the A/C system. I was there when they checked it out with foam
from a canister. A replacement of the rad. at $380 + VAT + labour + new fill up of the A/C was proposed to me.
I did't agree and asked for a fill up with gas and a fluorecent agent. So they did.
Back home I cleaned all the area of the rad.+ connections. Than I used I simple UV-neon light to illuminate the spot and I could easely see it was the connection (high press side) that was leaking. I toke two wrenches (one to hold and one to fasten) and
guess what...no leak anymore!
This is what I should do in your case : clean very thoroughly the area and than after a short ride, check again for leaks. If you think the connections are leaking, use ALWAYS two wrenches to fasten very CAREFULLY the line nuts. Saved me a lot of money !
If it is not the connections...you got already the explanation in former mails.
Good luck and share your experiences with the board!