RE: 2004 Dodge Ram Running Hot
Roger JRH, I agree with you that a failsafe could complicate diagnosing some coolant problems. For the most part though, a failsafe will let you get home or to a shop where you can fix the problem. If a regular thermostat fails completely it will close and you will overheat. A tstat failure usually means you have to pull over now, wherever you are, or risk doing permanent damage to your engine. If a failsafe goes bad then your engine will just run too cold.