liquid inlet 15 unfiltered liquid is guided to the raw side of liquid filter 1 situated radially outwardly from filter insert 2 in raw liquid inlet 15 the liquid here flows via a first connecting channel 14 1 that connects liquid filter 1 to a heat exchanger not shown such as an oil cooler via a clean liquid outlet 16 filtered liquid that flows downward from the clean side of liquid filter 1 i e from a region inside filter insert 2 exits filter housing 10 at the very bottom of filter housing 10 there is a central discharge duct 13 in which the two seals 33 1 and 33 2 of closing pin 3 are situated a second connecting channel 14 2 connects the heat exchanger to a region of central discharge duct 13 between the two seals 33 1 and 33 2 central discharge duct 13 has two segments 13 1 having a larger diameter and 13 2 having a smaller diameter in which seals 33 1 and 33 2 are situated in their sealing position i e in the closed position of closing pin 3 in this way discharge duct 13 is sealed in liquid tight fashion during operation of liquid filter 1 the liquid pressure prevailing therein ensures that closing pin 3 is held in its lowermost position spring 5 is supported with its lower end on filter housing 10 and with its upper end on.