Difficulty: Intermediate | Time: 45–60 minutes

1. Prepare vehicle. Ensure engine is cold. Disconnect negative battery terminal. Place drain pan beneath the thermostat tube location (front of engine block).
2. Drain coolant system. Open the radiator drain plug and allow coolant to flow into the pan. Close drain plug once empty.
3. Disconnect hoses. Carefully remove coolant hoses connected to the existing thermostat tube. Note hose positions for correct reassembly.
4. Remove fasteners. Unbolt the thermostat tube from the cylinder block using appropriate socket size (typically 10–13mm). Note bolt torque spec: 20–25 Nm (15–18 lb-ft).
5. Extract old tube. Gently pull the old thermostat tube away from the cylinder block. Inspect the sealing surface for debris or corrosion.
6. Clean mounting surface. Wipe the cylinder block seating area with a clean cloth. Remove any old gasket material or O-ring residue.
7. Install new tube. Position the new thermostat tube with the integrated O-ring aligned to the cylinder block. Insert mounting bolts finger-tight first.
8. Torque fasteners. Using a torque wrench, tighten bolts evenly to 20–25 Nm (15–18 lb-ft) in a cross pattern. Do not over-tighten.
9. Reconnect hoses. Reattach coolant hoses to the new tube in the same configuration as noted earlier. Ensure hose clamps are tight (do not crush hose).
10. Refill coolant. Add fresh coolant mixture (50/50 antifreeze and distilled water, or use genuine Range Rover coolant) until the system is full. Bleed air pockets by running the engine at idle for 2–3 minutes.
11. Check for leaks. Inspect the new thermostat tube connection and O-ring seating for any drips. Allow engine to cool, then top off coolant as needed.
12. Reconnect battery. Reconnect the negative battery terminal and clear any diagnostic codes if necessary.