[smally289]

Another way that I found was to remove the small bypass hose from the side of the thermostat housing & add water to the header tank with a garden hose with the motor running. Sticking a spare length of hose on the bypass hose fitting long enough to hang past the front bumper stops the water hitting the drive belt & making a mess.
As long as you keep the header tank full you can run it like this for several minutes.