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Properly test an Auto Thermostat

Testing a thermostat is a straightforward procedure that can save you both time and money by ensuring your vehicle’s cooling system operates efficiently. Here’s a simple step-by-step guide to test a thermostat:

  1. Safety First: Ensure the engine is completely cool before starting the test to avoid burns or injuries.
  2. Locate the Thermostat: Identify the thermostat’s location in your vehicle’s cooling system. It is typically housed in a metal casting where the upper radiator hose connects to the engine.
  3. Remove the Thermostat:
  • Disconnect the negative battery cable to prevent any electrical mishaps.
  • Drain some coolant from the radiator to a level below the thermostat housing to prevent spills.
  • Carefully remove the thermostat housing and take out the thermostat.

Boiling Water Test:

  • Fill a pot with plain water and bring it to a boil.
  • Submerge the thermostat in the boiling water using a tool to hold it without touching the pot’s bottom.
  • Observe the thermostat as the water continues to boil.
  • A functional thermostat should begin to open as the water reaches its specified temperature (usually between 180°F to 195°F or 82°C to 90°C).
  • If the thermostat does not open, it indicates that it may be faulty and needs replacement.

Inspect and Replace:

  • Examine the thermostat for any signs of corrosion, wear, or damage.
  • If the thermostat fails to open during the boiling water test or shows signs of damage, it’s advisable to replace it with a new one.

Reinstall the Thermostat:

  • Install the new thermostat into the housing with the jiggle valve (if present) facing upwards to allow trapped air to escape.
  • Reattach the thermostat housing securely.
  • Refill the radiator with the coolant you previously drained.
  • Reconnect the negative battery cable.

Test the Cooling System:

  • Start the engine and allow it to reach operating temperature.
  • Monitor the temperature gauge and check for any signs of overheating.
  • Ensure that the thermostat opens and closes as required to regulate the engine’s temperature effectively.

By following these simple steps to test and potentially replace a faulty thermostat, you can maintain the efficiency of your vehicle’s cooling system, prevent overheating, and avoid costly repairs in the future.