Looking at this perplexing problem I wondered if the larger hole on the vw case allowed some of the oil to drip back into the case. Few thoughts come to mind one is perhaps putting in a couple of elbows would help reduce the velocity and two perhaps drill an other hole to allow the blown out oil to drip back in. Ultimately a larger hole could help. Also the longer hose on other setups might actually increase the volume enough to help depressurization. A flapper valve near the case could also help as then the volume of blow out would be reduced due to the partial crankcase vacuum. Sure is a vexing dilemma.If I was having this problem I think I would fabricate a custom flapper plate/valve near the case.
