Here's a general guide. Specifics might vary slightly depending on the exact configuration of your engine bay, so referencing a repair manual specific to your vehicle's year and model is strongly recommended.
Tools You'll Likely Need:
* Socket wrench set: You'll need sockets of various sizes, probably including a 10mm and an 8mm.
* Ratchet: To turn the sockets.
* Extension(s): To reach tight areas.
* Flathead screwdriver: Possibly for prying or gently levering components.
* Pliers: Might be needed to help remove stubborn hoses.
* Drain pan: To catch coolant.
* New thermostat and gasket: Replace the thermostat with a new one and always replace the gasket.
* Coolant: You'll likely lose some coolant during this process.
Steps (General):
1. Drain Coolant: Locate the coolant drain plug (usually at the bottom of the radiator). Place your drain pan underneath and carefully open the drain plug to let the coolant drain. This is crucial to minimize the amount of coolant you spill.
2. Locate the Thermostat Housing: The thermostat housing is typically located on the engine block, near the top of the engine, where the upper radiator hose connects. It might be a plastic or metal housing.
3. Disconnect the Upper Radiator Hose: Carefully loosen the clamp securing the upper radiator hose to the thermostat housing. Use pliers if needed. Remove the hose. Some coolant will likely spill, so have your drain pan ready.
4. Remove the Thermostat Housing Bolts: Locate the bolts securing the thermostat housing to the engine block. These are usually small bolts. Use the appropriate socket and ratchet to carefully remove them. Keep track of these bolts and washers – they may be different lengths.
5. Remove the Thermostat Housing: Once the bolts are removed, gently lift off the thermostat housing. The thermostat and gasket should be visible inside.
6. Remove the Thermostat and Gasket: The thermostat is usually held in place by a simple friction fit. Carefully remove it. The old gasket should come off with the thermostat housing, but if it's stuck, gently pry it off with a flathead screwdriver. *Be careful not to damage the housing*.
7. Clean the Housing: Clean any debris from the thermostat housing and the mating surface on the engine block.
8. Install the New Thermostat and Gasket: Install the new gasket (if needed, some thermostats come with a new gasket already installed) into the thermostat housing. Carefully place the new thermostat into the housing, ensuring it sits correctly.
9. Reassemble: Carefully put the thermostat housing back onto the engine block, making sure it's aligned correctly. Replace the bolts and tighten them evenly to the manufacturer's specified torque (consult your repair manual).
10. Reconnect the Upper Radiator Hose: Reattach the upper radiator hose and secure the clamp.
11. Refill Coolant: Carefully refill the cooling system with the correct type and amount of coolant (consult your owner's manual). Bleed the air from the system by squeezing the upper and lower radiator hoses, and running the engine until the thermostat opens (allowing air bubbles to escape). Add more coolant as needed.
12. Check for Leaks: After refilling, start the engine and let it run for a while, checking carefully for any leaks around the thermostat housing and hoses.
Important Considerations:
* Repair Manual: A repair manual specific to your 2004 Ford Focus 2.3L is highly recommended. It will provide detailed diagrams, torque specifications, and other crucial information.
* Coolant Type: Use the correct type of coolant specified in your owner's manual. Mixing different types can damage your engine.
* Safety: Always let the engine cool completely before working on it. Coolant is corrosive, so wear gloves and eye protection.
This is a general guide; the exact procedure might differ slightly. If you are uncomfortable performing this repair yourself, it's always best to take your vehicle to a qualified mechanic.
