Hi, I have a 1994 honda accord that I used to pull a jet ski for 4 years. It pulled this ski great until one day it overheated like crazy. I was able to pull off and when I opened the hood, the coolant in the overflow was boiling. I was able to get it home eventually. I performed a flush and fill, changed the thermostat and never pulled the jet ski again. I had no signs of oil in the coolant, no coolant loss, no chocolate frothy oil mixture. Everything was good until today.

Today driving home I was zoning out listening to the radio and the news about the VT shooting and when I looked down and the temp was MAXED. I was close to the next exit so I Decided to push it so I could get it to the gas station. I tried to turn on the heater to help cool it down, but the air was stone cold.
When I was bout 500 feet away, BOOM! The radiator blew up - literally. :banghead: There is a 5 inch wide crack in the top of the radiator! When I opened the hood though, the radiator was cold, the overflow had coolant (cold) and the coolant all over the inside of the hood was also cold. How can this be? It sounds to me like an obstruction, so I'm automatically thinking thermostat, but I dont understand how this can be because the thermostat is only two years old and I replaced it with the genuine Honda thermostat. The odds of this going bad again seem almost impossible. The oil was a little low, but otherwise good.

Could this be a head gasket? Could the heater control valve to the heater core have anything to do with it? I'm lost as to how the coolant in the radiator could be so cold but the engine be so hot.

I'm debating now if I should keep this pile or just junk it. I have about 215000 on it right now and I just had the clutch replaced 2 months ago. Any advice or suggestions?
Thanks

Probably a head gasket.

What happens is: Compression pushing into the cooling jacket over pressurizes the system. Meanwhile, a pocket of air (from the compression leak) builds behind the thermostat. The thermostat must be fully immersed in water or it will not open. Temp and pressure keep building, the system is airlocked, and something's got to give...usually a radiator tank or a weak hose....

You've probably been leaking a little compression for a while, but the little bypass/check hole on the thermostat has been bleeding off the air, so it hasn't airlocked before...this time for some reason the buildup was faster than the air could purge from behind the 'stat..the check might have failed or the leak just got worse suddenly...

PS they will not have any flow to the heater core when airlocked, usually...that makes sense what you said about not being able to blow any heat out of it...