Why does my car temp go up when i have turned the car off?

Question

I recently had to have a new radiator put in my 97 Dodge Dakota because the old one blew up. Since I had it replaced my car temp. stays normal while driving but when i shut the car off the temp gauge goes up. I'm afraid something else is wrong besides the radiator and i'll have to change it again. Any ideas?

Answer 1

When you shut off the engine the coolant inside the system no longer circulates and cools. It is common for coolant measured in the engine to show an increase in temperature.  This should not be a huge increase and you may have something else going on that caused the original radiator issue. Some common general issues are: bad thermostat, air in the system, non working cooling fan or leaking head gasket. It may be worth your while to have it check out by a cooling system specialist.  

Answer 2

these are all good answers, so I can't add anything to it.

Answer 3

Are your cooling fans working? They should keep working for sometime after you have switched the car off.

Answer 4

Because there is no airflow, the water/coolant actually gets hotter for a short time after you turn the engine off.

Nothing to worry about.

Answer 5

That's normal. Heat rises, and that's where the Temp sensor is, at the top of your motor. What you're seeing is just the residual heat of the motor still dissipating after you turn it off. You probably just didn't notice it before, but now you're worried about it. If you hear gurgling, then there's a problem.

Not too likely you have an air pocket on a Dakota. That's mostly a problem with cars that have a transverse-mounted engines and complicated plumbing systems. Check to make sure you're getting heat out of the heater. If so, it should be fine for that.

Answer 6

Pretty much any vehicle with a gauge will show a similar effect.  Shut the car off, 10 minutes later start it, and the temperature will DROP to normal, rather than rise.  It takes a while for the heat to dissipate from the motor, and while stopped and turned off, there is no coolant circulation, and no airflow through the engine compartment.  Notice many vehicles have electric fans at the radiator that can keep running after the car is turned off because of this heat

An air lock in the system would prevent proper circulation while running, and would have no affect on the vehicle when it is turned off.