Thermostat Test

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2014 Honda Ridgeline, 2013 Honda Ridgeline, 2012 Honda Ridgeline, 2011 Honda Ridgeline, and 2010 Honda Ridgeline. However, it is still accessible from the selected car via links, so may be relevant.

Replace the thermostat if it is stuck in the open position at room temperature.

To test a closed thermostat:

Suspend the thermostat (A) in a container of water. Do not let the thermometer (B) touch the bottom of the hot container.

Fig 1: Checking Thermostat Opening Temperature
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Heat the water and check the temperature with a thermometer. Note the temperature at which the thermostat first opens, and at which it is fully open.
Measure the lift height of the thermostat when it is fully open.
Standard Thermostat

Lift Height: Above 10.0 mm (0.39 in.)

Starts Opening: 169-176°F (76-80°C)

Fully Open: 194°F (90°C)