You said it yourself, what the hose is for. PCV=Positive Crankcase Ventilation. Without a way to vent the oil system, you can build up pressure and start blowing out seals and leak oil in numerous places. Another reason to use quality oil and filter and change the oil and filter on a schedule.Yea we bought a hose barb and had to cut the end shorter...n got jb weld plastic supposed to do glue it in there today. What exactly does that hose do that goes in there?