Xantia HDi fuel filter

[John F]

My 1999 HDi is equipped with a large black plastic fuel filter with water drain valve and snap on connections with 2 pipes entering the top that uses a replaceable element. On the top in the centre of what I think is the lid is what looks like a 20 mm hex nut formed from the plastic; I used a box spanner to give maximum, all round, contact on this plastic "nut" but although I exerted a fair amount of torque whilst the filter was in situ the lid did not budge. I also noted that the whole filter turned slightly until it came up against the arms on the pressed steel support bracket on which it seats. Fearing that I would a. damage the "nut" by shearing it off b. distort the bracket or c. shear the pipes, I desisted. Can any one please advise me what is the best course of action to remove the lid (if it can be removed)? Though I suspect that the only safe method is to completely remove the filter body from the vehicle and place it in some padded vice jaws. Your answers will be appreciated.

[JohnD]

Disconnect the two pipes from the filter body. Preferably plug the ends to keep muck out. Use a suitable socket on the nut and turn the cover a quarter of a turn anti-clockwise to clear the locking lugs. Before starting, cover underneath with absorbent rags.

[John F]

Many thanks JohnD from John F