Auto Parts: Coolant Problems, blown head gasket, overflow tube

Question
I have a 1988 Toyota pickup 4wd with the 2.2 FI motor.  The problem I am having is that the truck is pushing all the coolant from the overflow tube in the resevoir.  its like its not circulating and its all being pushed into the resevoir from the radiator.  I drained, flushed, and even backflushed it.  I have put in many thermostats and I check those before I even put them in.  Im going to take my thermostat out and test it again.  I know the water pump is good.  I also dont get any heat out of the vents even though my engine is overheating.  I think the heater core is good because I havent smelled any antifreeze.  No antifreeze in my oil either so I am sure the gasket and my head is good.  If you have any ideas that I havent tried I would greatly appreciate it.

Answer
    It is almost certainly a blown head gasket.  This happens to 4 cyl Toyotas all the time.  The engine overheats, the gasket fails, and the head warps.  You will most likely have to install a new head, although it is possible that a good machine shop can repair the old one if it is not too far gone.