A lubricant pumping system includes a lubricant pump having a lubricant pumping space, a first seal configured to seal the lubricant pumping space, at least one signal detector, and a leakage detector for detecting leakage of a lubricant from the pumping space through the first seal and sending a signal to the signal detector in response to a detection of the leakage of the lubricant. The signal detector may produce a visual or acoustic output in response to receipt of the signal.