Coolant overflow boiling

blown head gasket or cracked head would be a fair answer

Its normal for the car to have antifreeze going to the overflow tank if thats what your asking.

If the thermostat is not opening, the engine will keep getting hotter as you drive. You could be low on coolant and have air pockets in the system which would cause the temp gauge to not be accurate. Is the radiator fan coming on when the tank is boiling ?

you could have a faulty temp gauge(air in the system) was my problem let it cooldown all the way....open radiator cap turn your heater on so water circulates all around the engine add coolant if needed it helps to gun the engine a little watch for flow of coolant then cap it.a closed thermosthat would also cause you car to overheat.

WELL YOU NEED TO DRAIN COOLANT LEVEL BELOW THERMOSTAT LEVEL.YOU HAVE TO DISCONNECT MAF SENSOR LOOSEN AIRDUCT 2 LARGE CLAMPS LOOSEN REMOVE 4 SCREWS TO AIR FILTER COVER LIFT UP REMOVE COVER. THEN REMOVE AIR FILTER AND HOUSING, FIRST DISCONNECT MAF SENSOR.YOU HAVE TO DISCONNECT THROTTLE CABLE AND SHIFT CABLE.YOU HAVE TO DISCONNECT REMOVE THROTTLE BODY COOLANT HOSES DISCONNECT IDLE SPEED CONTROL VALVE CONNECTOR AND DISCONNECT TPS SENSOR CONNECTOR. THEN REMOVE THROTTLE BODY ASSEMBLY. YOU NEED TO BUY NEW THROTTLE BODY COOLANT HOSES AND NEW THROTTLE BODY GASKET FOLLOW TOP COOLANT HOSE TO ENGINE BLOCK.NOW YOU SEE CAN AND REMOVE THE THERMOSTAT HOUSING REPLACE THE THERMOSTAT.BESURE TO HAVE EXTRA COOLANT ON HAND.BLEED COOLANT SYSTEM WHEN DONE.TO BLEED COOLANT SYSTEM REMOVE RADIATOR CAP ON OVERFLOW JUG.THEN OPEN BLEED SCREW ON THE WATER PUMP BYPASS HOSE PIPE JUST A LITTLE.POUR COOLANT IN THE OVERFLOW JUG UNTIL LEVEL STOP DROPPING.STOP AT COLD MARK ON JUG.CLOSE BLEEDER SCREW ON WATER PUMP BYPASS HOSE PIPE.CRANK VECHICLE CHECK FOR LEAKS. START UP ENGINE LET IDLE FEW MINUTES THEN CHECK COOLANT LEVEL ADD MORE UNTIL UNTIL LEVEL STOP DROPPING.PUT RADIATOR CAP BACK ON OVERFLOW RESERVOIR. LET ENGINE IDLE WATCH COOLANT TEMPERATURE GAUGE.WHEN GAUGE START CLIMBING. TURN OFF ENGINE WAIT FEW MINUTES TAKE A LARGE RAG OPEN RADIATOR JUST A LITTLE YOU HEAR HISS NOISE.WHEN PRESSURE STABILIZE DONT GET SCALDED BECAREFUL.OPEN CAP LITTLE MORE.IF COOLANT PRESSURE STILL BOILS OUT WAIT 20 MINUTES ADD MORE COOLANT TO RADIATOR OVER FLOW WHEN COOLANT LEVEL STOP DROPPING.PUT RADIATOR CAP BACK ON START VECHICLE UP LET IDLE UNTIL THERMOSTAT OPEN. THEN FEEL TOP RADIATOR HOSE FEELS HOT THERMOSTAT OPEN WATCH TEMPERATURE GAUGE.IF GAUGE TEMP START CLIMBING TURN OFF ENGINE WAIT A WHILE.CHECK AND ADD MORE COOLANT.WHEN THE ENGINE CAN IDLE TEMP GAUGE STOP CLIMBING YOU HAVE BLEED COOLANT SYSTEM.KEEP CHECK ON COOLANT LEVEL.

Hello: There are two metal pipes on the back of the engine thar carry the coolant from the driver side of the engine to the heater core and back to the engine. It is possible they may be rusted out. Also it could be head gasket failure, When it comes out check the coolant overflow tank on the passenger side under the hood and see/hear if it is gurgling. The overflow tank hose may be stopped up or it could be the wrong radiator cap. Hope this will give you a place to start. The radiator cap should be rated at 15psi

FLUSH COOLANT SYSTEM REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.BESURE TO USE 50/50 ANTIFREEZE AND WATER.TO RAISE BOILING POINT.PLAIN WATER WILL BOIL AWAY OR EVAPORATE CAUSING COOLING LOST WHICH MAKE ENGINE OVERHEAT.

I hate to tell you this but it sounds like a blown head gasket.

I think you could be right about there being air trapped in the system.
Or the heater core(radiator) is plugged.
Either way you need a pressurized radiator coolant pump to put the coolant in without air being trapped.
Although,i have seen it done by jacking the vehicle up high enough that the radiator was now higher than the heater core level, and then the coolant was put in.
But this is dangerous to try.

Finding the thermostat is easy. Just follow the top radiator hose back to the engine.
The question I have is how to get to the bottom screw of the thermostat housing.

Any Sugustions anyone?