coolant issues of sorts..??

[cfly86]

Right guys,
My 4a-ge 16v trueno is loosing coolant from somewhere, possible i think where the water pump is located? as its defnetly not the radiator leaking.

When i fill it up and go for a spin it's fine the temp sits nicely where it should and i think the water pump is ok (maybe needs a gasket replaced?)

But what i wanted to know was, have any of you's had similar problems and what would yous say is the common problem?
please and thank you

Conor.