Originally Posted by superdave
an engine needs the thermostat so the water stays in the radiator long enough to cool down. it will overheat every time without one. good luck
Not always. I had one engine (GM 350 in I-forget-what) that would never warm up over ~150 without a thermostat. Had an '85 Chevy Celebrity that wouldn't run up to 180 even with a new thermostat (replaced more than once). But it's true, *Some* vehicles can run hot w/o a thermostat.