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Home >> Cadillac >> 2006 >> STS Base, 3.6 7, RWD >> Repair and Diagnosis >> Engine Mechanical >> Cooling System (Mechanical) >> Engine Cooling System >> Diagnostic Information and Procedures >> Thermostat Diagnosis

Thermostat Diagnosis

Tools Required 

J 24731  Tempilstick. See Special Tools .

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 operating range, by rubbing 87°C (188°F) and 97°C (206°F) sticks on the outlet coolant pipe, located between the thermostat housing and the inlet radiator hose.

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