How to Replace the Thermostat of a 2003 Chevy Impala

by Lisa WamplerUpdated November 07, 2017
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Items you will need

  • 2003 Chevy Impala thermostat

  • 2003 Chevy Impala thermostat gasket

  • Screwdriver

  • Wrench

The 2003 Chevy Impala was a throwback to the horsepower hot rods of the 1960s and 1970s. Since they have higher horsepower output, people tend to drive them harder. If you’re an Impala owner and you have a lead foot, you should keep an eye on the thermostat. If you notice that the engine is not heating or cooling properly, it’s time to lay off the gas pedal for a while and change out that worn-out thermostat. If you put this task off, the engine can suffer catastrophic failure.

Locate the top radiator hose and trace it to the location where the hose is connected to the Impala's engine. The metal cover that the hose is connected to is the thermostat cover. Remove the clamp that holds the hose onto the cover with a screwdriver. Slide the clamp down the hose so it does not get lost. Pull the hose off the cover and slide it to the side.

Remove the thermostat cover by removing the two bolts that hold the cover onto the intake manifold of the Impala. Pull the thermostat off the intake once the bolts have been removed.

Locate the thermostat cover gasket and remove it. It usually sticks to the intake manifold, but sometimes it can pull off the intake and stick to the thermostat cover. The gasket can be thrown away. It will not be used again.

Remove the thermostat from the inside of the intake manifold by pulling directly up on it. It will come out easily.

Place the new thermostat into the intake manifold with the correct end facing out of the intake. The thermostat will be marked with the end that should be placed in the "up" position.

Place the new gasket onto the intake manifold and replace the thermostat cover. Bolt the cover into place using the bolts that were previously removed.

Slide the radiator hose back into place and tighten it back onto the thermostat cover with the clamp. The clamp should be tight to prevent any fluid leaks.

Run the Impala until it reaches the standard operating temperature and then check the radiator hose and the area where the thermostat cover and the intake are bolted together for any leaks. If there is a leak in the hose, the clamp should be tightened. If there is a leak due to the gasket failing, RTV silicone can be used in place of the standard Impala thermostat gasket.

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