This is a diagram of my SVO system. The valves are the much-maligned pollack solenoid valves. They (presumably) worked OK for the PO, and have worked OK for the 7-8 months that I have used them for daily commuting & longer trips. The VO filter was a baldwin BF1212, now a fleetguard FS1212 10 micron filter, with a coolant filled copper coil wrapped around it to heat it. The final heat exchanger is a Doucette 1/2 ton coiled tube in shell purchased from frybrid.



This particular loop should not give headaches to a displacement lift pump the T location at V2 feeds the return flow into the intake, and make up of the injected fuel is freely taken from the VO line to the tank.

While I have oil consumption issues, soon to be addressed, I have no real problems with power or trapped air. Since the VO fuel sender is I believe corroded and gives no signal, I suck air now and then. This can be backfed down the VO line with my purge valve setting, as drawn. If excessive air is introduced into the system (filter change), I can select the appropriate system and push it out w/ the hand pump. The item marked 'sight glass' is as translucent right angle diesel line filters- whatever autozone sells for the final filter on the 240D. Another one, not shown is right above the LP/IP unit, so it's right between V1 and the engine. They let me see what fuel is in the respective circuits- always useful. Purge is verified when diesel is visible in both sight glasses (note to self-the new canola I filled the filter with looks just like diesel) WVO is typically dark brown. Air is visible in these filters, doesn't seem to restrict the flow. The banjo bolt is replaced with a solid bolt to prevent cross-contamination.

When I replumbed the system & added the HX, I used nothing special, 3/8" and 3/4" heater hose from autozone, Nylon T's & barbs from Mcmaster, stainless hose clamps from autozone.

I just spent the weekend driving around pittsburgh & surroundings with the family, challenging enough in a well powered automatic, let alone a 240D. I was able to reach or exceed posted speed limits on those crazy hills & get away from stop signs on 10-15% grades without much drama, VO or D2.

As far as SVO goes, I take my cue from frybrid, using a final heat exchanger & taking care to switch hot, block the banjo & purge properly.

If the banjo is not blocked, or if you do not purge properly, your diesel fuel system may be contaminated by VO. You might change your diesel filter.