Here is the situation.  99 legacy filled with coolant, ran half hour with funnel full of coolant until bubbles came out, fans cycled many times, released any bubbles from right side upper plug on radiator.  Car drives without overheating for long periods without leaking.

Shut the car down, come back out and there is an 8 oz puddle under the car under left side front of engine timing cover.  Replaced the radiator.  Coolant is 50/50 mix.  Radiator is new and no leaks there.  New cap.  Eventually lose enough coolant that we are back at refill and bleed.

Is the water pump my problem?  Not looking forward to that job as the timing belt cover bolts are very rusted and won't come out easily.

sounds like water pump or t-stat housing. closely inspect the area i suspect you should be able to see a wet spot where its coming from. it could even be a loose hose clamp on the lower hose.

If you just replaced the radiator, strongly suspect a loose hose clamp. 

clean/dry the suspected area, get a pressure test kit loaned-out from the parts store, look for the leak while under pressure.

waterpump definitely possible - miles on it?

 

Heater circuit hose from the water pump. Check it out for pin holes. 

Cheers 

Bennie