Tools You'll Likely Need:
* Socket wrench set: Probably need a 10mm, possibly an 8mm.
* Flathead screwdriver: May be needed to pry off some clips or hoses.
* Phillips head screwdriver: Possibly needed depending on your specific vehicle.
* Pliers: For stubborn hose clamps.
* Drain pan: To catch coolant.
* New thermostat: It's best to replace it with a new one while you're in there.
* New gasket (if needed): Check the condition of the old gasket before reinstalling.
* Coolant: You'll likely lose some coolant during this process.
Procedure (General Steps):
1. Cool Down the Engine: Let the engine cool completely before starting. Hot coolant can cause serious burns.
2. Drain Some Coolant: Locate the coolant drain valve at the bottom of the radiator (usually a petcock). Open it carefully into your drain pan to lower the coolant level. This will reduce the mess when removing the thermostat housing.
3. Locate the Thermostat Housing: This is typically located on the engine block, near the top of the engine, and connected to the upper radiator hose. It will have a housing, often made of metal or plastic, enclosing the thermostat.
4. Disconnect the Upper Radiator Hose: Carefully loosen and remove the hose clamp securing the upper radiator hose to the thermostat housing. Gently pull the hose off the housing. Some coolant may spill, so have your drain pan ready.
5. Remove the Thermostat Housing: This is where the specific tools and techniques will vary most depending on your Impala. There might be bolts holding the housing in place (likely 8mm or 10mm). Remove these bolts carefully. The housing might be held on with clips, which might require a flathead screwdriver to carefully pry loose.
6. Remove the Thermostat: Once the housing is off, the thermostat should be visible. It's usually held in place by a spring clip. Carefully remove the clip and the thermostat.
7. Inspect the Thermostat and Gasket: Examine the old thermostat to ensure it's functioning correctly. Check for any cracks or damage. Also, carefully inspect the old gasket for any damage. Replace the gasket if it's damaged or worn.
8. Install the New Thermostat and Gasket: Install the new gasket (if necessary) onto the thermostat housing. Place the new thermostat into the housing, ensuring it's seated correctly.
9. Reassemble: Reinstall the thermostat housing, tightening the bolts to the manufacturer's specified torque (check your repair manual). Reconnect the upper radiator hose and secure it with the hose clamp.
10. Refill Coolant: Refill the radiator and coolant overflow tank with the correct type of coolant for your vehicle (consult your owner's manual).
11. Check for Leaks: Run the engine for a few minutes and check for any leaks around the thermostat housing and hoses.
12. Bleed the Cooling System (if needed): Some vehicles require bleeding the cooling system after refilling to remove air bubbles. Consult your owner's manual for instructions.
Important Considerations:
* Repair Manual: A repair manual specific to your 2004 Chevy Impala 3400 V6 is highly recommended. It will provide detailed diagrams, torque specifications, and other crucial information.
* Safety: Always wear safety glasses and gloves when working with coolant. Coolant is toxic.
* Professional Help: If you're not comfortable performing this task, it's best to take your vehicle to a qualified mechanic.
This is a general guide, and the exact procedures might differ slightly depending on your specific vehicle's configuration. Always refer to your owner's manual or a repair manual for accurate and detailed instructions.
