blown head gasket???

[D-bird]

Hello,
I have an '89 T-Bird with a 3.8 V6 that has 85,000 miles on it. I recently started having trouble with it running hot. It's an intermittant problem. When it does overheat its after I've driven it 5 or 10 miles. The temp will go up rapidly and the heater blows cold. It pushes the water out of the radiator into the overflow tank.
I've replaced the radiator cap with a new 16# cap and I replaced the thermostat with a new 192 degree thermostat. There are no apparent coolant leaks.
There is no coolant in the oil. There doesn't appear to be any white smoke out of the exhaust.
At first I thought it was a problem with the cap or thermostat because its an intermittant problem.
Every engine I've seen that had a blown head gasket has had coolant in the oil or belched out white smoke, and started losing power. My car doesn't have any of those problems, but it pushes the coolant out. Any ides of what the problem could be?
I'm hoping it isn't a blown head gasket, but if it is I was wondering if anyone has had success with any of the ceramic cooling system sealers to "fix" a blown head gasket. I know thats not a real fix, but will it buy me some time until I can replace the head gasket?
Thanks in advance for your help!
Darrel

[scbird1]

If you still have the original radiator I would replace that first along with a new themastat and a fresh mix of 50-50 water and antifreeze. If your head gaskets are on there way out and you do a rebuild a new rad would be a good investment. Every sc I have bought needed a new one due to age. It sounds like you might have some air in your system as well. I bought all my radiators from radiator express for about $160.