I recently replaced the waterpump in my '89 300E and, thanks to the discussion here, I also placed an aluminium tube in the neck as well, although there were no leaking problems. turns out now I do have a small leak, not at the radiator neck, though, but at the point where the overflow tube (from the expansion tank) enters the radiator. there is an elbow that seems to insert into the tank via some 'latches' it appears...... anyone have any ideas of why it might leak there? Is there an o-ring inside?? Can't appear to get it off - easily anyway.

cheers and thanks