On my 99 E300, that line comes off a thermosat type heater mounted toward the front of the head which then connects to the filter housing.

If WVO has clogged everything up maybe you need to run a tank of B100 through it to dissolve any remaining goo?

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)