Thermostat Diagnosis

Thermostat Diagnosis

Tools Required

J 24731 Tempil Stick

Use one of the following procedures in testing for a malfunctioning thermostat.

Thermostat Test Procedure Using Tempil Sticks

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.

1. Use a tempil stick in order to find the opening and the closing temperatures of the coolant thermostat.

* J 24731-188 tempil stick melts at 87°C (188°F). The thermostat should begin to open.
* J 24731-206 tempil stick 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.