2013 Tribeca cooling

[AtMyWitsEnd]

My sister-in-law has a 2013 Tribeca that has been giving her cooling problems since last yr. Took it to the dealership…replaced sensor, sensor connector, replaced radiator, thermostat, hoses… everything to do with cooling of this car. Well now there is no coolant flow. We give up

 

[Ecmbuster]

Has anyone looked for coolant flow from the water pump? Impellers have been known to break/strip.
By now, this Tribeca should have overheated multiple times.
Thermostat opening / closing can be measured between the upper and lower hoses with a laser thermometer / sensor. Coolant to the heater core should heat quickly and return back to the engine. The water pump will also flow internally without opening or closing the thermostat until the engine needs to cool down.
Is there something restricting coolant flow?