Yes, it would do it with the breather totally disconnected, so just an open hole on the axle housing. And just a piece of 3” - 4” blue air line from the bulkhead fitting sticking up that I left open. So there shouldn’t be anything causing the locker to push oil through the copper line and out the dummy 4” blue line.You removed the breather completely from the axle correct? Mine did this when the breather fitting was clogged.