Overheating?

If your car is overheating and there aren’t any other symptoms, the problem may be with your thermostat.  Having experienced this myself, I wanted to share the info.  It’s always good to also check for recalls.  If you have an OBD tool, check for any codes.  Here’s a complete list.

Oil change instructions?

Why Does My Thermostat Cause Overheating?

The thermostat regulates engine temperature by controlling coolant flow.  When the temperature reaches a certain level, it allows the coolant through.

How do I know if it’s faulty?

Symptoms include overheating, fluctuating temperature readings, and poor cabin heating.

How to Test Your Thermostat

1. Removal:
   • Let the engine cool completely if it has been running.
   • It’s typically found inside the thermostat housing, which is where the upper radiator hose connected to the engine.
   • Drain some coolant from the radiator to avoid spills.
   • Remove the housing. This may involve removing bolts and disconnecting hoses.
2. Inspection:
   • Visually inspect the thermostat for any signs of damage, corrosion, or excessive wear.
   • If it’s visibly damaged, it should be replaced regardless of further testing.
3. Testing:
   • Fill the pot with water and place the thermometer in the water. Ensure the water level is enough to completely submerge the thermostat.
   • Place the pot on the stove or heat source and slowly heat the water.
   • Once the water reaches around 80-90°C (176-194°F), which is below the typical opening temperature, use pliers or tongs to submerge it in the water.
   • Continue to heat the water and monitor the temperature.
   • It should start to open at its specified opening temperature (usually between 88-92°C or 190-198°F for most cars).
   • Keep heating the water until it reaches a few degrees above the opening temperature to ensure it fully opens.
4. Results:
   • If it opens fully, it’s working properly.

Refill and Reinstall the Thermostat

1. Before installing, clean the housing. Remove old gasket material and debris for a good seal.
2. Place the thermostat in the same orientation as the old one. Ensure it fits securely.
3. A new gasket will prevent leaks.
4. Reattach the housing. Tighten the bolts, but don’t over-tighten to avoid cracking the housing.
5. After reassembly, refill the radiator with coolant. Use the type recommended by your car manufacturer.
6. Bleed the System:
   • If your vehicle has a bleeder valve, open it slightly. Coolant and air may start coming out. Close the valve once you see a steady stream of coolant without air bubbles.
   • If there’s no bleeder valve, watch the coolant flow through the radiator. Air bubbles coming to the surface indicate air is escaping.
7. Add Coolant as Necessary:
   • As the engine warms up, the level in the radiator may drop. Add more coolant as needed to maintain the proper level.
8. Look for Thermostat Opening:
   • Observe the coolant flow or temperature gauge. When the thermostat opens, the upper radiator hose will become hot, and the coolant level/flow might change.
9. Check for Air Bubbles:
   • Continue to run the engine until no more air bubbles are coming out of the radiator or bleeder valve. This may take some time, so be patient.
10. Replace Radiator Cap and Check Overflow Tank:
    • Once the engine has reached normal operating temperature and no more air is visible, replace the radiator cap.
    • Make sure the coolant overflow tank is filled to the appropriate level.

When to Seek Professional Help

If you’re unsure about any step, seek professional assistance. It’s better to be safe than sorry.

Final Thoughts

Replacing your car’s thermostat is a rewarding DIY project and will save you money.

1. How often should a car thermostat be replaced? Generally, every 10 years or as needed.
2. Can a faulty thermostat increase fuel consumption? Yes.
3. What happens if I install the thermostat incorrectly? It can cause overheating.
4. Is it necessary to use a specific type of coolant? Always use the coolant type recommended by the manufacturer.