CoachGeo,
thanks for the courteous disagreement. admittedly I don't have tons of SVO experience, but I've been running Biodiesel for over 200K miles. I think my 300SD fuel filter is very small, but haven't replaced it yet (only put 2k on since recently getting this car). I am doing an SVO conversion on it as soon as I get a chance, and have a much larger filter, with a water drain, to replace it. I've run Biodiesel in some pretty cold temps (B100 at 20F is my personal record) and running a large heated filter is one of the reasons I've gotten away with it. I also like to use cartridge style filters because there is less worry about the glue coming apart when exposed to high temps, similar to what's been reported on spin-on style filters...although I haven't seen that one myself.

the reason I think Lars might have an injector problem is this: If you have an injector that has a good spray pattern when tested, but does poorly on a chatter test, it will still run reasonably well on diesel fuel, but will get the nozzle tip hot when run on SVO. The chatter test shows that the nozzle can close quickly, keeping the flame from approaching the tip. Kind of like the carb cleaner-match trick. When you stop spraying you let go of the top quickly and the flame goes out, if you slow the stream down the flame finds it's way back to the can. The same thing is easily demonstrated with a bad injector and a nozzle tester. If you overheat the tip the needle will start dragging when returning to it's seat, and then you have a motor that runs poorly.

In you defense; you are right about lots of guys running small pre-filters without troubles, so there is plenty of evidence I'm overcautious in regards to filter volume. I suppose practice is better than theory here.

Joe

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1978 300SD
Running Biodiesel/SVO, 2 tank system
127,000 Miles