Thanks, Andy; your fix has a lot going for it. In a lot of searching nationwide over a week or two I could find only one hose product with a diameter suitable for fitting over the existing tube (to be cut off near its fittings) for a solution similar to yours, and that hose was rated for milk. Getting hydraulic fittings made up to the heavy-duty high pressure hose and then welded to our metric fittings was going to run two or three hundred dollars in our market, so I took Walter's advice and just bent it out of the way, pretty much the way your hose goes. ["Just" bent it isn't really accurate; it's challenging in the cramped areas upside-down and underneath, and took a goodly portion of my levers and tweakers and odd-shaped wrenches.] Not pretty but after several re-tightenings of the threaded fittings, no leaks or rubbing in the ensuing few thousand miles. 'Twere more neatly and easily done prior to installing the axle -- and with a torch to smooth things -- but then it's hard to know just where it needs to move to and how much. [Though two or three swaps ought to teach that.]
It's a much cleaner and more elegant swap with the external circulating tube removed and the holes plugged neatly with M-B oil drain plugs. And for, let's say, 80% of these swaps that is the way it's done: viola! Mine looked all nice like that when it left Joe's shop. By the time I arrived home a day's drive later, at least 75% of the nice new lube was gone, except for what was all over the rear - - underside sopping and outside slick. So what determines the difference between those of our swaps that blow out their contents and those that don't? Where's the variable?
I'd much rather we proactively find and fix it - control the situation at its source - than have to mess around coming up with improvised reactions to unpredictable crisis.
I'm not at all pleased that I haven't been up to the challenge myself. I've asked some of the most experienced and respected 113 pros about it with little result. In Britain they carve off a bit of the understructure to clear the tube.
Here's a fairly major failure that occurs, apparently randomly, in 20% (?) of one of our largest and most favorite improvements, and we haven't figured it out -- yet.
Yours in motoring happiness,
Denny ;~)