Its a boxer van and Ive got a problem, its leaking deisel. I lay under the front looking up and can see where its dripping from. looking at it its a circle about the size of 10p piece made of rubber with a white plastic cross in the middle (looks similar to the end of a torpedo). I turned it to the right to try and tighten but still drips i turned it slightly to the left and it stopped but its dripping again today there are 2 black pipes feeding a cast unit with this on it, it lookes like somekind of filter or tube either screwed in and its worn the thread out or its pushed in im only assuming . if you need any more detailes please ask. cheers.