Mazda Repair: over heating, coolant level, 2000 mazda 626

Question
i have a 2000 mazda 626 iv changed the thermostat the electoric fans and flushed the system and i am some how losing water ive already checked radiator.what else can it be

Answer
Does it over heat quickly or does it overheat as the water level drops.  If your loosing coolant a pressurized leak test may lead you to the source, line plug, hose or connection.  Water pump seals can fail and leave a very small trace that they have.  In many cases the leak is very minor and almost unnoticeable until the coolant level begins to drop as a result after moderate use.  Water pump seals can often pass a pressure leak test especially when the engine is hot due to seal expansion.