Going down the highway one night, I started running really hot, so I pulled over and turned my car off (a 73 eldorado). She didnt turn off. To the contrary, she started running faster. So I jumped out, pulled the battery terminals off, pulled the alternator wire off (Ok, I panicked) and started pulling plug wires off the distributor. Still didnt stop, but at this point, it was smoking and actually SPARKING out of the exhaust manifold. But it eventually stopped. Anyway, the next day, I hooked everything back up, and she cranked fine, but smokes like a traine from under the hood. I think I know the answer here, but I'm in denial. Does anyone else think I blew the engine? Piston rings, etc?

:welcome: Your engine may be fine, but more details would help. Why did it get hot? Did you lose all your coolant? Did the thermostat fail to open? How high was the oil level? Did you hear any detonation rattle? How does it sound now at idle? What does the oil look like now? Any water in the oil or tail pipe?
I've pegged the temp guage needle on at least two different engines, one more than once, the other to the point that the engine died and would not start for an hour, then drove it home, very slowly, anyway they both are still running good, no rebuilds, no teardowns, no water where there shouldn't be, they're both Ford 302s, and if they can take it... Look it over real well before you start tearing anything down. If it's okay, then you may want to change the oil right away, and maybe the trans fluid, since it is cooled by the radiator.

the engine got so hot it was dieseling, meaning the combustion chamber was so hot it was igniting the fuel/air on heat alone, no spark... so you could have did anything to the battery or spark plugs and it would still go... plus, if the battery is disconnected, then pulling the wires woudln't do anything... the only real way to shut the engine down from there is to just let it do its thing, or starve it of fuel somehow...

The best way to stop an engine once it diesels is to smother the carb with a towel, so it chokes with no air.

The thermo was fine, as I replaced it the day before. I think it was either the waterpump (Though I heard no belt squeel, the inside fins could have at broke off) or some kind of blockedge. The only coolant I lost was from it boiling over when I stopped it. I havent checked the oil yet. However, before it went nuclear, the tranny stopped shifting. I was driving at 10mph in 1st gear on the shoulder trying to get home. (It has a newly rebuilt tranny and the fluid level was fine) The only thing that really concernse me is the smoking from under the hood. But tommorow I'm going to check all the fluids for water, so I'll post again then. Sorry for the rambling.

If you replaced it the day before I'd immediately suspect a bad replacement one...

I agree, replace it again, but make sure you have the right one.
On the caddy big blocks the coolant sustem has the bypass right under the thermostat, it's a hole about an inch in diameter, make sure you have the right thermostat with a disc on the bottom that controls bypass, or if the bypass has been plugged permanently, a chevy thermostat will work.

I'm betting the new thermo was in backwards... Sounds like it WAY overheated, something you wouldnt see on the temp gauge as no coolant was getting to it. I've seen this before.

You head gasket is smoked. Maybe the head. And maybe the block. Replace the head gaskets and see if its OK.

is to leave the transmission in gear. :coolgleam