1997 Ford Taurus pushing antifreeze out of holding tank after warm up

Hi,I have a 97 taurus that pushes the antifreeze out of the resevoir tank after it warms up.Have replaced the cap,isnt overheating(until it gets low on fluid).The only code I can get out of it is a P0412,dont know if it has anything to do with my problem. Help!!!

Are your sure its leaking out the cap? Those plastic tanks become brittle over time, and crack causing the antifreeze to leak out. Secondly check if you have heat, if you don’t then you could have a clogged heater, and if you don’t have a bypass hose installed that was part of a service campaign a long time ago then that too could be the cause.
Does your temperature gauge fluctuate? Is your antifreeze brown and muddy?

The P0412 code means you have a California Emission car equipped with a electric air pump that pumps air into the exhaust for a short time on start up. There are two air valves that shut off the air. Circuit (A) is causing the code, and is not related to above antifreeze problem.

I am sure that it is leaking out of the cap but that doesnt mean the tank cant be cracked around the threads,will have to look at that. I have heat,but the bypass hose? Not sure about that,where is it located?Thanks for your help!

It you trace the heater hose on the drivers side of the engine after the two coolant sensors, there should be a tee in it thats close to the transmission dip stick, and from there goes across the fire wall.

Other possibilities are bad thermostat, blown head gasket, water pump with rusted away impeller.