Thermostat: Testing and Inspection

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a pencil like device. It has a wax material containing certain chemicals which melt at a given temperature. Temperature sticks can be used to determine a thermostat's operating range, by rubbing 87° C (188° F) and 97° C (206° F) sticks on the thermostat housing.

TOOLS REQUIRED
^ J 24731-188 188° F Tempilstick
^ J 24731-206 206° F Tempilstick

1. Use a tempilstick in order to find the opening and the closing temperatures of the coolant thermostat.
^ J 24731-188 tempilstick melts at 87° C (188° F). The thermostat should begin to open.
^ J 24731-206 tempilstick melts at 97° C (206° F). The thermostat should be fully open.

2. Replace the coolant thermostat if it does not operate properly between this temperature range.