Don't know if this will help you any, but mine started running hot awhile back, so I put a new thermostat in it. Shortly thereafter I was driving along, and it ran hot again...really hot, I did not notice it until it was starting to spew out (funny how that gets your attention). I replaced the thermostat again and it was fine.
The truck had sat a good while before I bought it, so I think maybe there was some crud in the system that might have blocked both the old and the new thermostat...seems to be good now.
I don't think the new thermostat that failed was completely closed, but was enough so that it overheated on me. You can check if it is thermostat by squeezing the hose that goes from the radiator to the top of the engine where the thermostat is. When you start up it should be a bit hard to squeeze, once the engine warms up and the thermostat opens up it will be easier to squeeze. If the engine is hot and that hose is still hard to squeeze, the thermostat is not opening up.
I think I explained that right....hope it helps man
