My 2001 toyota celica gts had been overheating. I had a new radiator put on, the mechanic said that the water pump had been slowly leaking for about 2-3 yrs but did not need replaced yet. It was not the block, nor the gasket, nor the thermostat. I still have to add antifreeze every other day due to it leaks out from somewhere. I thought maybe it could be the radiator over flow container has a pin hole in it and as Im driving the pressure pushes the antifreeze out due to if the car is running and not moving, there is no leak that can be seen. please help me.