Overheating and boiling in the overflow reserve tank

Not all products (like thermostats) bought new, work. Did you test it before you installed it? (dip in boiling water, it shoulod open) also, was it installed correctly? If upside down it probably wont be able to open. it would explain whats going. on. Good luck!

you have a blown head gasket.. doesn't have to have coolant in the oil for a blown head gasket... if hoses are rock hard when running then you have exhaust leaking into the coolant via a blown head gasket...

May be a bad radiator cap allowing air through

Answer could be a faulty thermostat,or it could be a sign that your head gasket is about to blow ,or last of all your timing could be out of sync.

Answer 2 from Inventus: It means your cooling system is funtioning properly. In a system having a coolant recovery tank, coolant in the radiator is always up to the brim, hot or cold. There is negligible or no air space. When coolant in the radiator expands sufficiently due to warming from the engine, it will squeeze past the pressure cap's bottom seal and flow into the recovery tank. (If no provision for such expansion was present, the expansion would rupture the radiator or your hoses.) Only coolant within the radiator is under pressure, and because of this pressure (together with the elevated boiling point that the "anti-freeze" permits), it normally does not boil. But once past the pressure cap's bottom seal, the overflow is at atmospheric pressure and therefore boils.
This boiling is usually unnoticed after a short, i.e., local, trip because the cooler coolant already in the recovery tank quenches it. But after some highway driving the influx of more hot overflow heats up all the coolant in the recovery tank to the (unpressurized, i.e., "natural") boiling point.
As the engine cools when shut off, the contracting coolant in the radiator sucks back coolant from the recovery tank. Fluid in the recovery tank should never be below the "full hot" or "full cold" marks, lest air be sucked in.
-- BETTER ANSWER ==
Your cooling fans are not turning on. It is not normal for your overflow tank to boil like that. It is true that your radiator is overflowing into the reserve tank, but that means yourr adiaotor is boiling. Check for blown fuses or relays for your cooling fans. IF theya re fine. run your engine for about 15 minutes and drive. When you temp level is at normal operating temp open your hood with the engine runing and see if your fans are on. If they are, then you may have a bad thermostat or a plugged radiator, or a bad water pump. If the fans are not on, get your cooling fan switch replaced if your car has one. Check your temp sending sensor

contact me at [email protected] and ill explain from there

Why did you change the head gasket Patrick,
Was the engine missing before you did this,or did you over heat the engine from low coolant?
If the miss was there before you may have burnt a valve,

Check the passage of the coolant if there are debris or leaks. There might be a puncture on the engine block somewhere.

you seem to have a blown head gasket

you may have a clog or your water pump is not working.

Ford 2000 Taurus

To solve the problem you have the things to do in this order;

) When the engine is cold top off the radiator with fluid. (When the pump was replaced the fluid should have been also)
) Make sure the radiator fluid has anti-freeze in it. This is also anti boil also !
) Add fluid to the overflow reservoir.
) Make sure the drive belt was replaced on the water pump.
) With the engine running, you can add fluid to the radiator for the first minute or so. You want to get air pockets out.
) Replace radiator cap.
) Let car warm up. When it's hot you should get the radiator fan coming on.
) When it get hotter the air-conditioning fan may come on.
) If the fan does not come on, the heat sensor is probably bad.
) If all fans come on, and it overheats, you may have a bad thermostat. Trace the upper radiator hose to where it connects to the engine. That's where it located.

Do not operate the engine when it overheats, You will damage the head gaskets and cause radiator fluid to leak into the cylinders.
If you smell radiator fluid in the exhaust fumes, it may already be leaking.