Water pumps on cars have a hole that will leak coolant out if the pump seal fails. Does the pump pulley have play or does the water pump bearing make noise? The way an automotive shop would locate the leak is by removing the radiator cap and attaching an adapter that screws on in place of the radiator cap. Something that looks like a bicycle pump with a pressure gauge attached to it is used to "pump up" pressure to simulate pressure generated when the cooling system is at operating temperature, the leak is then found sometimes it is obviously leaking from a coolant hose or cracked housing, failed gasket or water pump, sometimes the engines cooling system needs to be inspected from below or inspected using a mirror and flash light. If the coolant loss is still evasive dye can be added to the cooling system that may indicate the source of the leak. A mysterious coolant loss may even be a sign of a head gasket that is not sealing well.
I just replaced the water pump and it is leaking from a hole above the water pump next to a freezout plug and under the intake i can put my finger in the hole and the water stops when i take my finger out of the hole it leaks profucely again but I cant see it without taking the intake off. Rob a shade tree mechanic i know says its the freezeout plug and another guy i know says i have to take the intake off and repalce a part but he dosnt remember what it was called. I need help.