im surprised no one has said this... or maybe they did and i missed it, it almost sounds like the water pump went up on you.. i would say to see if it is circluating but with a thermostat that cane be done, maybe take the thermostat out, and leave the cap off the radiator and look to see if it is circulating

 

Water pumps do not fail in this manner. They are a mechanical type with one moving part, the bearing. If the engine is turning, and the fanbelt is not missing, the pump will circulate coolant. Water pumps fail only when the bearing dies and they begin to wobble, or leak. Even then, they are still circulating coolant.

 

hmm.. interesting cause ive had a few waterpumps fail without leaking... but who knows that may have just been a freak time

 

Nope. Not buying the trapped air theory. Trapped air goes straight to the radiator when the thermostat opens. IF it opens

Ah, OK, but IIRC water becomes steam at sea level pressure at 100°C. Pressurized steam higher than that. If your engine is boiling but the coolant does not circulate, the thermostat is not opening. I wouldn't blame the electric fan if the coolant in the radiator is not hot. If hot coolant is not circulating to the radiator, it makes no difference what fan you have. Go to Ford and get a 190° thermostat. At least then the coolant will circulate. If it still overheats when the coolant circulates, we'll start taking potshots at your fan again.

 

Oh, I've seen any number have a bad bearing but the seal hasn't failed. Yet.

 

Just about everything is new on this block including the water pump, not to say that it couldnt be the problem, but its less likely.

I just hate to pull that thermostate hosing off again as it makes such a mess and is a pain to seal up.

I guess I'm going to give topping it off again a shot, and lift up the front end. The theromostate should open allowing me to see coolent moving and thus eliminate the waterpump as the problem.

FYI I'm using a high flow thermostate, not a Ford. My brother is using the same one in his Fox Body with no problems.

 

Take the high flow thermostat out. Foxbodies use a horizontal flow radiator and yours uses a vertical flow. Coolant flows through horizontal radiators slower allowing for more time to cool. Try the normal volume thermostat to see if your coolant just needs more time in the radiator.

ETA does your lower radiator hose have the spring in it? It is possible to suck the lower hose shut under high flow situations and then you dont have any coolant flowing.

 

I did double check the lower hose and it wasnt collapsing with RPM.

Great point on the Thermostat!

 

If you are worried about air in the system, take the temperature sending unit or thermostat off and fill the radiator until coolant comes out the thermostat or sending unit hole. You can then button everything up and should have minimal air in the block. Another option would be the small hole in the thermostat.

I must say that it is unusual for this is coming up after 100 miles of no issue if it is an vapor lock issue in the cooling system. Have you run the engine with the cap off of the radiator? What happens when the temperature opens the thermostat? Do you see coolant movement?

Final jab. Have you verified the temperature of the coolant in the radiator versus your e fan thermostat? Shoot the cap or top of the radiator with a thermo gun. If it reads above 190 and your fan is not on...it is still a problem whether it is the cause of the underlying issue or not.

 

Are you sure you installed the head gaskets correctly with the word "Front" towards the front of the engine? It is a common mistake to install one of them backwards as alot of people want to have the printing on the gaskets the same, but doing it that way usually results in one gasket being installed backwards.

These gaskets are both installed correctly. Notice they both say "Front" on them, but the printing design is not the same between the two. Match the printing and one of them is backwards leading to rapid overheating: