Inspection After Removal

WARNING: This page is about a different car, the 2013 Infiniti FX50. However, it is still accessible from the selected car via links, so may be relevant.

Check that valve in thermostat is completely closing at normal temperature.
Place a thread (A) so that it is caught in the valve of the thermostat. Immerse fully in a container filled with water. Heat while stirring.
The valve opening temperature is the temperature at which the valve opens and falls from the thread.
After checking the maximum valve lift, lower the water temperature and check the valve closing temperature.

Fig 1: Inspecting Thermostat
Courtesy of NISSAN NORTH AMERICA, INC.

Thermostat (Standard): Refer to "THERMOSTAT ".
If the malfunctioning condition, when valve seating at ordinary room temperature, or measured values are out of the standard, replace thermostat.