I pull off the fuel return

The second solenoid plumbed.
The hose on the left comes from the engine. The blue goes into the original diesel return, and the shiny grey goes to the WVO return. You can also see the left side coolant supply wrapped here.

I added this double shut-off

Photo album generated by album a MarginalHack written by David Ljung on Thu Jan 28 03:53:11 2016