Car overheats and pushes fluid back into the overflow tank.

I had a bad head gasket.I used Bars Leak Gasket Repair and it ran great for
about two years.I made a mistake by adding alittle more to a cold
engine.After that it started to overheat and the temp gauge would max out.It
already had a new waterpump and new belts.I replaced the thermostat and
the radiator.It overheats but no steam comes out.There is no water in the
oil.It pushes all the coolant into the overflow tank but when I start to loosen
the radiator cap,it draws it all back into the radiator.The hoses don't leak and
the heater works fine and I can see no leakage inside the cab.Also I see very
little water coming out the tailpipe.I am not sure what I should do next.