1. Make sure the engine is completely cool and drain the radiator; this can be done either by loosening the drain plug from the bottom of the radiator or by removing the lower radiator hose. After the coolant drains completely you can tighten the drain plug and/or reattach the lower radiator hose.
2. The thermostat on the 4.0 ranger is located underneath the throttle body area, so you have to remove the plastic 4.0L cover (just remove 2 bolts), and remove the air intake tube (just loosen the clamps on each end).
3. At this point you should have enough room to access the thermostat housing. Remove 3 bolts from the housing and move it aside to expose the thermostat.
4. Pay attention to the orientation of the old thermostat before removal, the new one should go in exactly the same way, not upside down.
5. Install the new thermostat with a new seal and reinstall the housing. Take care not to over tighten the bolts on the plastic housing, just snug them. Reinstall the air intake tube and plastic cover.
6.Fill the radiator and overflow tank with coolant and make sure you bleed the cooling system of air. Check for any leaks.
