[DeTomaso] Overheating remedy suggestions welcome...

[Tom Di Iulio]

hello all,
some of you may remember that my original overflow tank finally rusted thru
while i was at the big bend race in april. with the help of mike frazier and
john taphorn (and another GT40 owner whose name escapes me), the bottle was
patched and i ran the race with no issues.
since i've been home, the car has begun running hotter with this past week
finally being a show stopper.
here's what i have done or know so far...
1. when the engine is smokin' hot, the radiator is ambient temperature. the
fans do not come on (they wouldn't 'cause the rad never heats up).
2. i removed the thermostat and watched it open and close in alternate bowls
of hot and cold water. i have also run the car w/o the thermostat and the
radiator is still cool and the engine is overheating.
3. i removed the heater hose from the top fitting on the original water pump
and stuck a wire down the hole to confirm the impeller blades are turning
when the pulley is turned via the belt.
4. while conducting the test this morning to see what's what, i noticed a
small trail of water boiling out of the area where the intake manifold,
passenger side head, and block come together. this
may be a result of overheating the last couple days, not sure.
5. the oil has been checked and is fine. level is good and no indication of
water and oil mixing.
6. when the overflow tank blew in ft stockton, the amount of water used to
refill the system was not as much as i would've guessed based on the amount
of coolant on the ground. i have refilled the refill tank twice since then
which includes this morning. there are no leaks of coolant under the car.
7. the aluminum radiator (from quella) was installed by me a week prior to
the big bend race and was functioning as expected until the overflow tank
blew. i also had the system power flushed by a local shop to remove any old
coolant and/or debris in an effort to protect the small cooling tubes from
blockage in the new radiator.
guys, i'm at my wit's end...not sure what else to inspect. i understand i
may now have to replace a head gasket but i think that's a result of the
overheating, not the cause......although i've been wrong before.
comments/advice?

tom di iulio
denver, co