Why does your temp gauge rises after you turn the car off you have a 2000 doge intrepid?

Answer 1

This is common in many vehicles. While the engine is running, heat is created by combustion in the combustion chambers of the cylinders; it flows out to the piston, valves and cylinder block to cooler areas and ultimately the cooling sources like fins and water jacket. Exhaust gases and oil also carry off heat.

When the engine stops, no more heat is created in the combustion chambers, but they remain the hottest part of the engine. Meanwhile, the oil, water and air flows have stopped, so the cooled areas are no longer being aggressively cooled. Since the vehicle has usually stopped moving once the engine has shut off, there's no more wind to cool fins, radiators and oil coolers.

Heat continues to flow out of the combustion chamber and heats the most cooled areas of the engine beyond their normal running temperature until combustion chamber temperature drops. Since temperature gauges usually measure oil temperature at some distance from the hottest regions, they show an increase in temperature as the heat flows from those to cooler areas.

This phenomenon is related to how hair dryers often overheat once shut off and have to cool before they can be started again: airflow takes the heat away from the upstream temperature sensor, and when the fan stops the heat flows back. There is often an audible "click" as the overheat sensor trips.