The thermostat is an important, though inexpensive, part of your 2004 Impala that is often overlooked when servicing the vehicle. If the thermostat stops functioning properly, it can cause a number of different issues with your car. These issues include the car overheating in the worst case and not getting any heat inside the car at best. Replacing the thermostat is a simple fix that will only take about 30 minutes to do.
Drain the engine coolant so that it falls below the thermostat level by opening the drain plug at the bottom of the radiator and draining it into a catch pan.
Follow the upper radiator hose to the thermostat housing, remove the clamp with a screwdriver then pull the hose away from the thermostat housing.
Remove the thermostat housing with a socket, extension and ratchet.
Clean the old gasket off the thermostat housing and the engine with a scraper, using a light back and forth motion.
Insert the new thermostat with its spring going into the engine.
Position the new thermostat gasket onto the motor then secure the thermostat cover on top.
Tighten the thermostat housing bolts snugly with the socket and ratchet. Do not over-tighten them or you will strip the threads.
Reattach the upper radiator hose onto the thermostat housing and tighten the clamp with the screwdriver. Pour coolant into the coolant reservoir.
Start the engine and check for leaks.
