Vehicle propulsion cooling

1. A system, comprising a computer including a processor and a memory, the memory storing instructions executable by the computer to:

measure a temperature of a vehicle propulsion subsystem;

determine a time threshold based at least in part on a thermal mass of the vehicle propulsion subsystem;

actuate a first countermeasure when the temperature exceeds a first threshold;

measure an elapsed time from when the temperature exceeds the first threshold;

determine that the elapsed time exceeds the time threshold; and

then, actuate a second countermeasure;

wherein the countermeasures include actuating a vehicle climate control subsystem and opening at least one vehicle window.

2. The system of claim 1 , wherein the countermeasures further include deactivating the propulsion subsystem and opening a vehicle hood.

3. The system of claim 1 , wherein the instructions further include instructions to actuate opening the vehicle window when one of a precipitation sensor detects that there is substantially no precipitation and an occupant sensor detects that the vehicle is unoccupied.

4. The system of claim 1 , wherein the countermeasures further include deactivating the propulsion subsystem and the instructions further include instructions to actuate an electric coolant subsystem to circulate a propulsion coolant when the propulsion subsystem is deactivated.

5. The system of claim 1 , wherein countermeasures further include deactivating the propulsion subsystem and the instructions further include instructions to move the vehicle to a safe stopping zone before deactivating the propulsion system and opening the vehicle hood.

6. The system of claim 1 , wherein the instructions further include instructions to determine whether the vehicle is occupied and to actuate the climate control system only when the vehicle is not occupied.

7. The system of claim 1 , wherein the countermeasures further include deactivating the propulsion subsystem and opening a vehicle hood, and the instructions include instructions to actuate the countermeasures in a predetermined sequence, the sequence being actuating the climate control subsystem, opening the vehicle window, moving to a safe stopping zone and deactivating the propulsion system, and opening the vehicle hood.

8. The system of claim 1 , wherein the instructions further include instructions to actuate another countermeasure when the temperature exceeds a second threshold.

9. The system of claim 1 , wherein the temperature is at least one of a cylinder head temperature and an engine coolant temperature.

10. A method, comprising:

measuring a temperature of a propulsion subsystem with a temperature sensor;

determining a time threshold based at least in part on a thermal mass of the vehicle propulsion subsystem;

actuating a first countermeasure when the temperature exceeds a first threshold;

measuring an elapsed time from when the temperature exceeds the first threshold;

determining that the elapsed time exceeds the time threshold; and

then, actuating a second countermeasure;

wherein the countermeasures include actuating a vehicle climate control subsystem and opening at least one vehicle window.

11. The method of claim 10 , wherein the countermeasures further include deactivating the propulsion subsystem and opening a vehicle hood.

12. The method of claim 10 , further comprising actuating the countermeasure of opening the vehicle window when one of a precipitation sensor detects that there is substantially no precipitation and an occupant sensor detects that the vehicle is unoccupied.

13. The method of claim 10 , wherein the countermeasures further include deactivating the propulsion subsystem, further comprising actuating an electric coolant subsystem to circulate a propulsion coolant when the propulsion subsystem is deactivated.

14. The method of claim 10 , wherein the countermeasures further include deactivating the propulsion subsystem, further comprising moving the vehicle to a safe stopping zone before deactivating the propulsion system and opening the vehicle hood.

15. The method of claim 10 , further comprising determining whether the vehicle is occupied and to actuate the climate control system only when the vehicle is not occupied.

16. The method of claim 10 , wherein the countermeasures further include deactivating the propulsion subsystem and opening a vehicle hood, further comprising actuating the countermeasures in a predetermined sequence, the sequence being actuating the climate control subsystem, opening the vehicle window, moving to a safe stopping zone and deactivating the propulsion system, and opening the vehicle hood.

17. The method of claim 10 , further comprising actuating another countermeasure when the temperature exceeds a second threshold.

18. The method of claim 10 , wherein the temperature is at least one of a cylinder head temperature and an engine coolant temperature.

19. The system of claim 1 , wherein the time threshold is based at least in part on a property of an engine of the propulsion subsystem.

20. The method of claim 10 , wherein the time threshold is based at least in part on a property of an engine of the propulsion subsystem.