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How to Install a Thermostat on Cars

by Contributing Writer; Updated June 12, 2017

Replacing the thermostat in a Dodge car will ensure that the truck runs smoothly, with minimal risk of overheating. The thermostat governs the coolant as it is distributed throughout the engine. When the engine starts getting hot, it triggers the thermostat to open and allow coolant to flow. When the engine cools, it triggers the thermostat to close. This is a constant cycle when the engine is running.

Under The Hood:

 How to Install a Thermostat on a Dodge Ram 1500

Open the hood to access the engine compartment. Follow the upper radiator hose to the engine.

Loosen the hose clamp with pliers. Squeeze the tabs on the hose clamp, and pull the hose off the thermostat housing.

Unbolt the thermostat housing with a socket wrench. Place the cover and the two bolts to the side.

Pull the thermostat out of the housing. Remember how the thermostat came out of the housing.

Scrape the gasket material off the surfaces of the thermostat housing with a putty knife or razor blade.

Insert the new thermostat with your fingers. The thermostat will sit in the housing.

Place the new gasket on the surface of the thermostat housing. Ensure that the bolt holes match up.

Bolt the housing together with a socket wrench. Ensure that both bolts are snug.

Clamp the hose onto the thermostat housing. Hold the clamp together by the tabs with pliers until the hose is secure on the piping. Release the pliers to tighten the clamp.

Open the radiator cap, and check the fluid level. Fill to the top if necessary.

Items you will need

  • Pliers

  • Socket wrench

  • Socket set

  • Putty knife

  • Razor blade

  • New thermostat

  • New thermostat housing gasket

  • 1 gallon of coolant

 How to Install a Thermostat on a 3.8L Mustang

Remove the radiator hose from the thermostat housing by loosening the band clamp that holds the hose onto the housing. Use a flathead screwdriver or a nut driver. Pull the hose off of the housing, and drain any excess fluid trapped in the radiator hose into a bucket.

Take out the two bolts that hold the thermostat housing onto the intake manifold of the Mustang with a wrench, and pull the housing off of the manifold.

Pull the thermostat out of the intake manifold, and remove the paper gasket that sits on top of the machine base of the intake manifold.

Place a new paper gasket onto the machine surface of the intake manifold, and place the new thermostat back into place. The end that must stick out of the engine is marked "top."

Put the thermostat housing back onto the intake manifold, and bolt it back into place. Reattach the radiator hose, and tighten it down.

Start the engine, and let it warm up. Check the mating surface of the intake manifold and the thermostat cover for any leaking. If there are leaks, place RTV silicone on each side of the thermostat gasket to prevent future leaks.

Items you will need

  • 3.8L Mustang thermostat

  • 3.8L Mustang thermostat gasket

  • Small bucket

  • Wrench

  • Screwdriver

 How to Install a Thermostat in a 2001 Passat

Place the front of the vehicle off the ground with ramps or jack stands. Set the emergency brake or place a wheel chock behind the rear tire for safety.

Place a drain pan under the lower radiator hose that is capable of holding 5 gallons of fluid.

Remove the radiator band clamp with pliers and pull the hose off the radiator. Fluid flows from the hose and the radiator; catch it all with the drain pan.

Follow the lower hose to the water pump. The thermostat housing bolts onto the water pump. Remove the hose from the thermostat housing with the pliers. Inspect the hose for dry rot. If you locate any, discard the hose and use a new one.

Remove the two bolts that secure the thermostat housing to the water pump with a 10mm socket.

Pull the housing, gasket and thermostat off the water pump. Discard the gasket and thermostat.

Clean the surfaces of the water pump and the thermostat housing to ensure a proper seal.

Place the spring end of the thermostat into the housing and then place the gasket onto the base of the thermostat housing.

Place the thermostat housing against the water pump and secure it with both 10mm bolts.

Slide the radiator hose onto the end of the thermostat housing and on the inlet tube of the lower radiator. Secure both ends with the hose clamps.

Open the radiator cap and drain all of the radiator fluid into the radiator. Close the cap when finished.

Items you will need

  • Ramps or jack stands

  • Pliers

  • Drainage pan

  • 10mm socket

  • Towel

  • Funnel

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.

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