How to Install a Thermostat on Ford Cars

by Contributing Writer; Updated June 12, 2017

That Ford car trucks are still on the road is a testament to the die-hard attitude Ford car had when the company built the Ford car. That attitude can only go so far, however. Now that your Ford car has a lot of miles on it, you must pay attention to the cooling system--in particular, the thermostat. Engine buildup can cause it to fail, and if that happens while you have a full payload, you can cause severe engine damage that could cost thousands to repair.

Under The Hood:

 How to Install a Thermostat on a 302

Release the radiator cap from the center of the top of the radiator by rotating the cap in a counterclockwise direction.

Locate the petcock plug on the driver’s side of the base of the radiator, then position a large container underneath the petcock plug.

Loosen the petcock plug with a wrench until radiator fluid begins to drain out of the plug and into the container. Close the plug with the wrench once the radiator fluid falls below the upper radiator hose, as determined by looking into the radiator through the cap opening.

Disconnect the water-pump hose and the top radiator hose from the thermostat housing. Each hose is secured with a clamp. Loosen the bolt on the clamp with a nut driver and pull both hoses off the housing.

Remove the two securing bolts from the sides of the thermostat housing, then pull the housing off the engine. Pull the thermostat out of the engine. Note that the large metal spring on one side of the thermostat faces the engine.

Insert the new thermostat into the engine with the thermostat’s spring facing towards the engine.

Apply gasket sealant to each side of a new thermostat gasket and press the gasket onto the back of the thermostat housing.

Place the thermostat housing over the thermostat and tighten the housing’s two securing bolts with a wrench.

Slide the water-pump and upper radiator hoses onto the thermostat housing and tighten the clamp on each hose with a nut driver.

Pour the radiator fluid that was drained back into the radiator and twist the radiator cap onto the radiator.

Items you will need

  • Large container

  • Wrench

  • Nut driver

  • Gasket sealant

  • Thermostat gasket

 How to Install a Thermostat in an F-350 Diesel

Open the hood. Allow the motor to cool off so that you will not be scalded by hot coolant. Locate the thermostat housing by tracing the upper radiator hose from the driver’s side of the radiator to its termination at the thermostat housing.

Remove the cap from the white plastic coolant bottle at the front of the engine bay. Place a drain pan under the radiator drain petcock on the lower side of the radiator on the driver’s side of the truck. Remove the petcock by rotating it counterclockwise with a 19mm wrench. Replace the petcock and tighten it in a clockwise direction once the coolant has fully drained.

Remove the clamps from both ends of the upper radiator hose with a pair of pliers. Pull the hose from the radiator and from the thermostat housing, using a twisting motion. Set the hose and clamps aside.

Spray penetrating fluid on the three mounting bolts on the thermostat housing and let it soak in for a few minutes. Remove the three bolts with an 8mm wrench turned counterclockwise. Remove the thermostat housing from the water pump and set it and the bolts aside.

Remove the thermostat housing from the water pump to reveal the thermostat. Carefully pry the thermostat up with a flat-blade screwdriver if necessary. Clean the mating surfaces on the thermostat housing and at the water pump with a rag.

Place a new thermostat into the water pump with the pointed end facing upward. Install a new O-ring gasket into the groove on the thermostat housing mating surface of the water pump. Position the thermostat housing back onto the water pump and tighten the three bolts with a torque wrench to 15 foot-lbs.

Push the upper radiator hose back onto the radiator inlet and the thermostat housing until it is fully seated at both ends. Replace the hose clamps in their original position with a pair of pliers. Refill the coolant that you drained from the radiator back into the white plastic coolant tank and replace the cap. Start the engine and let it warm up. Check for leaks and retighten your connections if necessary.

Items you will need

  • Drain pan

  • 19mm wrench

  • Pliers

  • Penetrating fluid

  • 8mm wrench

  • Flat-blade screwdriver

  • Rag

  • Thermostat housing O-ring gasket

  • Torque wrench

 How to Install a Thermostat in a Ford 4.0 Liter

Park your car or truck on a level surface. Wait for the engine to completely cool. Open the hood and remove the radiator filler cap (this unscrews by hand).

Place a bucket under the vehicle beneath the driver's side of the radiator. Reach under the radiator and turn the drain petcock towards the front of the car. If you have difficulty turning the petcock by hand, clamp a pair of vise grips to it and turn it using those as a handle. Allow enough coolant to drain out of the radiator so that you can see the top of the metal fins inside the radiator when you look in through the open fill cap. Close the petcock.

Trace the coolant delivery hose from where it comes off radiator to where it joins the thermostat housing. The thermostat housing will be located on the top of the engine block, toward the front. It is metal and the delivery hose will feed into it and there will be two additional hose coming off the housing.

Loosen the hose clamps attaching the hoses to the thermostat housing by turning the hose clamp screws counter-clockwise with a flat head screwdriver. When the clamps are loose enough to spin around the hose, pull the hoses off the housing.

Remove the four bolts holding the housing cover in place with a socket wrench. Lift the housing cover off. Inspect the gasket underneath the housing, replace it if it is brittle to the touch or looks worn. Scrape off the old gasket with a paint scraper put a new one in its place.

Remove the old thermostat from its position in the housing by simply lifting it out.

Install the thermostat into your Ford 4.0 liter by placing it in the same position as the old. Make sure that the silver top is facing upward and the arrows on the top are pointed toward the radiator.

Replace the thermostat housing cover and bolt it into position. Re-attach the hoses and tighten the hose clamps. Fill the radiator with new coolant and replace the filler cap.

Items you will need

  • Bucket

  • Vise grips (if needed)

  • Flat head screwdriver

  • Socket set

  • Paint scraper (if needed)

  • New thermostat housing gasket (if needed)

  • New thermostat

  • Engine coolant

 How to Install a Thermostat in a Ford 8N

Follow the radiator hose from the radiator to the location where it connects to the engine of the Ford 8N tractor. Remove the hose from the engine by loosing the clamp that holds it onto the water pump with a screwdriver. Pull the hose off the water pump.

Pull the thermostat and the thermostat out of the radiator hose. The housing for the thermostat is located inside of the hose. The thermostat sits inside of the housing. If the thermostat you purchased came with a new thermostat housing, pull the housing out of the hose.

Place the thermostat inside of the radiator hose and housing with the thermostat pin facing out of the hose. If a new housing is being used, place it into the hose first. Position both pieces in the hose so the pin slightly protrudes from the radiator hose.

Place the radiator hose back onto the water pump and secure the clamp.

Items you will need

  • Screwdriver

  • Ford 8N thermostat

  • Thermostat housing (optional)

 How to Install a Thermostat in a 1993 F150

Locate the cover for the thermostat by following the top radiator hose to where it connects to the engine. The thermostat cover is connected to the hose and is bolted to the intake manifold on the F150. Remove the two bolts that hold the thermostat cover onto the intake manifold with an adjutant wrench. Pull the thermostat cover with the hose still attached upward and then push them off to the side so you can access the thermostat.

Pull the broken thermostat out of the intake manifold of the F150 and discard it. Place the new thermostat into the intake manifold with the end marked "top" facing upward out of the engine.

Pull the old paper gasket off of the intake manifold and discard it. Place a bead of silicone RTV (room temperature vulcanization) gasket maker around the area where the gasket was placed. This will create a seal to prevent fluid from leaking between the intake and the thermostat cover. Allow the silicone to dry for 15 minutes.

Place the thermostat cover back onto the intake manifold and bolt it back into place with just your fingers. Do not tighten with a wrench. Allow 15 minute for additional drying of the silicone and then tighten with a wrench.

Items you will need

  • Wrench

  • 1993 F150 thermostat

  • RTV gasket maker

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.