Here is the complete step by step guide on how to change a thermostat on a Ford Ranger. The job can be done easily within half an hour for a professional. Ford Ranger’s engine bay is not complicated and it will take about an hour for someone who needs to read this in order to start the work. Before you start these steps, make sure you have parked the car for at least 30 minutes to let the engine cool down.

Step 1 Locate where is the thermostat

There are two hoses attached to the radiator. One is for coolant to flow out from engine to the radiator and another one is for coolant to flow from radiator into engine. The thermostat sits in between the engine and the radiator and it usually connects to the radiator hose where coolant will travel out from radiator to the engine. The reason why it sits there is because it block the coolant from going into the engine when the engine is cold. This is to warm up the engine as soon as possible. Follow the top hose from the radiator and you will find out where the thermostat is. There will be thermostat housing with three nuts so you will not be able to see it even you know how thermostat looks like. This is a picture of the location of a thermostat in a Ford Ranger.

(Image from Ford40.com)

Step 2 Drain the coolant

Once you have located the thermostat housing, you can disconnect the coolant temperature sensor connector and then drain the coolant by removing the radiator drain plug. Prepare a pain to keep the coolant. Now you can remove the three bolts around the thermostat housing.

Step 3 Remove the thermostat

The thermostat can be seen obviously once the housing is removed. The picture below here show how it sits in between the engine and radiator. You can use a wrench or pliers to remove the thermostat. It may be tight but you can twist a little bit to get it out. If the thermostat has never been changed for a long time, the gasket may wear out and it will stick within the housing and engine. Use clean rag and cleaner to clean it up.

Step 4 Replace a new thermostat

Make sure you buy a correct thermostat base on your Ford Ranger model year. The best way is to bring the old one to spare parts shop and get the same one. The direction of the thermostat to go in is very important, wrong side will make the car overheat. The best way to know which way the thermostat go is to remember it when you take it out. Keep in mind that the spring side is always towards to the engine just in case if you forget it. For Ford Ranger, the spring side will face just in front of you if you are standing in front of the car. To install a car thermostat, use wrench to mount it in. Below here is a thermostat diagram in a car engine for more understanding.

Label 3 is the thermostat, label 4 is the gasket, and you can obviously see the housing in the diagram.

Step 5 Restore everything

Now place the thermostat housing and fix the three bolts. Remember to reinstall the drain plug and put in a new coolant if it is dirty. Otherwise you can use the old coolant. Now open the radiator cap, start the engine and observe if the coolant is “moving” after the engine warms up. If it is moving means the new thermostat is working properly.

Tips for changing a thermostat

• To speed up the process, you can drain the coolant until the level is just below the thermostat.
• A thermostat in a car engine seldom wears out. The symptom of a thermostat wear out is the car experience overheating. This is because the thermostat valve did not open to let the coolant flow into the engine when the engine is hot.
• For more information, see how do I fix my car thermostat, Ford Ranger repair manual.