Boiling over and no clue why??? 1995 F150 V8
 

1995 F150 V8 - My truck was getting exceedingly hot so I put a new thermostat in it. It still got to boiling. So I checked to see if I had put it in backwards-NO. So then I put the thermostat in some boiling water to see if it would open and yes it did. So now what do I do. This truck has never even hinted at getting hot. Water seems to be flowing ok but not sure exactly how to check that. HELP

is it just water in the system? plain water has a much lower boiling point than coolant.

water pump

sounds like water pump. does the heater blow out hot air? most times heat wont blow hot if water is not circulating. whats the temp gauge read?

it seems the bottom of radiator is clogged. water will not run out of little drain plug. what's the change radiator flush would clear this? Must be rust.

easy way to tell unhook the radiator hose that goes from the bottom hose to the engine(do this with a cold engine) unhook from the engine, not the radiator or you're wasting your time hold it up so you dont lose all your water and have someone star the engine. if its not stopped up water will come out. If you get no water unhook hose from water pump to radiator, if no water flow or very little, pump is bad. if you get a real good flow then radiator is clogged

never had a water pump that didn't make noise when it went bad.
Thanks will try that test.

I never had one that did make noise. But I have only lost 2 GM pumps. GL with it~

Did you pull a heater hose from the core to purge the air? I put in 2 stat brand thermostats and they all failed. Went to ford and problem was gone. By chance do you have a collapsed hose when it gets hot? Your water pump turns off the belt so i would guess if its turning its pumping some type of water...