Buick/Olds: 94 Buick Skylark Coolant DUMP!, losing coolant, buick skylark

Question
After test driving a used 94 Buick Skylark Custom with a 2.3 I4 in it with 114,000 miles, I bought it. Ran beautifully right up to the trip home from the DMV after buying it. As i was turning onto my street, the temp gage rose steadily to redline. The low coolant light came on as well as the High Temp light. According to the nice long trail following me down my street i was obviously losing coolant fast. I made into my driveway, shut off the engine, and got under the hood in time to watch the remaining cooling pouring out of what appears to be a pressure relief drain coming out of the center of the firewall through a rubber elbow aimed at the ground. I am assuming this perhaps is a pressure relief from the heater core to prevent the coolant blowing into the car interior. I am not sure what came first, the coolant dump or the overheating. The only thing i can figure with my not-a-mechanic mind is either the thermostat is stuck shut allowing pressure to build high enough to force the drain, or else whatever is on the other end of that little drain in the back of the firewall has malfunctioned and is stuck open. Any ideas? I am searching for a chiltons or equivalent as we speak...

Thank you for your time and help...

Answer
After a search of TSB's (service bulletins on your car, the only one remotely connected to your problem is one about the need to be sure your radiator cap is good, as that can lead to coolant lose.
I believe your problem began with overheating (check thermostat) and dumped your coolant as a result.
advise...get a new radiator cap and thermostat, refill coolant. check temperature closely for an hour after starting engine.