I was pondering the use of the small diameter tube that runs from the Mercedes engine in the Roland C.II curving up to the front of the rollover bar. What was that? I did some research and found that it is referred to as a breather tube. OK, does that mean an overflow tube? Maybe.
Then, looking at the excellent photographs of Leo Stevenson's DFWs in the Customer Models photo section of the WnW site, I see that the mid-production version seems to have this kind of tube running up to the middle of the top wing, but the Late version has one attached to the port side of the radiator.
If they are overflow tubes, both the Roland C.II and the DFW Late tubes would be positioned to blow hot radiator fluid back toward the cockpit... Not a good thing, so I suspect they weren't for hot overflow.
Any information on the use and purposes of these radiator tube arrangements?