Note: This guide is for a 4.0L engine. If your vehicle has a different engine, the steps may vary slightly.
1. Open the hood of your Aerostar.
2. Locate the thermostat housing. It is usually located at the front of the engine, near the top. It will have a hose connected to it.
3. Remove the upper radiator hose. Use a wrench to loosen the clamp that holds it in place, and then pull the hose off of the thermostat housing.
4. Place a drain pan under the thermostat housing. This will catch the coolant that will drain out when you remove the thermostat.
5. Remove the thermostat housing bolts. There will be two bolts holding the thermostat housing in place. Remove them using a wrench.
6. Lift the thermostat housing off. Be careful not to spill any coolant.
7. Remove the old thermostat. It will be located inside the thermostat housing. Use a screwdriver to pry it out.
8. Inspect the thermostat. Look for any signs of damage or wear. If the thermostat is damaged, replace it with a new one.
9. Install the new thermostat. Make sure that the new thermostat is properly seated in the thermostat housing.
10. Replace the thermostat housing. Bolt the thermostat housing back in place.
11. Reattach the upper radiator hose. Clamp it in place with a wrench.
12. Refill the coolant system. Add coolant to the radiator until the level reaches the "Full" mark.
13. Close the hood of your Aerostar.
Test the thermostat:
- Start your Aerostar and let it warm up.
- Feel the upper radiator hose. If it gets warm, the thermostat is working properly.
- If the thermostat is not working, it may need to be replaced.
