My 1998 Land Rover Discovery 2 TD5 started to leave a trail of drips of diesel on the road which I only noticed upon seeing the oil pattern left following some rain.  The drips were forming very slowly, but were clearly coming from the area of the fuel filter.  Close examination revealed that it wasn’t leaking from the filter or the push on pipe connectors, but was instead leaking where the connectors screw into the filter housing.

There is a copper washer on each of the connectors that is supposed to make a seal against the filter housing.  I replaced the copper washer with a new one and refitted the connector, but the leak persisted.

Upon examining the surface of the filter housing I could see that it was pitted with corrosion.  This was stopping the copper washer sealing properly.  I thought I would try some PTFE tape on the threads to see if this would help.

The PTFE thread tape did the trick.  The joint has remained leak free for some time now.