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 (4).
J 24731 Tempilstick
• | J 24731-188 tempilstick melts at 87°C (188°F). The thermostat should begin to open at 90°C (194°F). |
• | J 24731-206 tempilstick melts at 97°C (206°F). The thermostat should be fully open at 107°C (225°F). |