How to Replace Your Car Thermostat (15 Easy Steps)
The thermostat is one of those car parts that is relatively cheap and easy to replace yourself. Although the parts are inexpensive, the cost of a mechanic’s labor can make the replacement cost higher.
We recommend searching online for your exact vehicle’s manual. If you can get a factory service manual or a third-party repair manual, even better.
Here are some general steps you should follow to replace the thermostat in your own vehicle. Steps to Replace a Thermostat
These steps are common to almost any vehicle that needs a thermostat replaced, and you should be able to understand what is involved in the repair process.
1) Prepare your tools
Gather your tools: clean drain pan, rag, new thermostat, new thermostat housing gasket, pliers, ratchet set, safety equipment (safety glasses, gloves), torque wrench, torque specs for your vehicle, plastic scraper, funnel.
2) Wait for the engine to cool
Make sure your car is cool (has not been driven recently) and in a clean work area. Typically, you should let your car cool for at least 3 hours before working on the cooling system.
3) Open Cooling System (Radiator Cap)
Open the radiator cap and keep it in a safe place. If you notice any leaks near the cap, replace the radiator cap as well.
4) Get a drip tray
Place a drain pan under the radiator drain plug underneath your car. Make sure the drain pan is clean if you want to reuse the coolant.
5) Drain the coolant
Turn the drain plug to drain the antifreeze/coolant into the drain pan. You should drain enough to expose the thermostat (usually about half). Some people take this opportunity to change their coolant if it is brown or if it hasn’t been changed in a long time.
Always store coolant out of reach of animals and children. Antifreeze has a sweet smell but is highly toxic to people and animals.
6) Loosen the thermostat housing.
Use a ratchet to loosen the screws that secure the thermostat housing to the engine. You may need to remove the radiator hoses if they are in the way when removing the thermostat. The gasket should also be removed. Many manufacturers require that you replace the thermostat housing gasket along with the thermostat.
7) Remove the thermostat (if the thermostat is faulty)
Check the engine from which you just removed the thermostat housing to find the thermostat itself. It should look like a cylinder with a metal ring and valve on top. You should be able to remove the thermostat by hand. There may be a part number, temperature rating, or other numbers that can help you decide what to buy. If that doesn’t solve the problem, call your local auto parts store and they can help you find the right replacement part.
8) Remove any sealant residue
Use a plastic scraper to scrape any remaining gasket residue off the housing and the motor flange where the housing attaches. If the mating surfaces are not smooth, leaks may occur later. Be careful when scraping as it may scratch if it is made of a softer metal such as aluminum.
9) Install new thermostat (replaces car thermostat)
Insert the new thermostat into the motor connection in the same orientation as the old thermostat, spring side down and valve side up. This will ensure proper functioning and minimize leaks.
10) Install the new gasket onto the thermostat housing
Place the new gasket onto the flange of the thermostat housing, being careful not to cover the holes. Some vehicles have the gasket installed on the thermostat before actually installing it, so it is important to determine the exact vehicle before doing this.
11) Reinstall the thermostat housing
To replace the housing, first align and hand tighten the screws, then use a torque wrench to tighten the screws according to the manufacturer’s instructions. Too loose can cause leaks or burst hoses, too tight can damage the aluminum housing or damage the threads on the engine block.
12) Refill Coolant
To refill coolant, pour coolant from the drain pan directly into the radiator or coolant reservoir. The funnel minimizes the risk of spilling coolant all over the engine compartment.
13) Bleed the Radiator and Replace the Radiator Cap
Bleed the cooling system by removing the cap at the highest point of the cooling system. This is often the radiator cap, but some vehicles have a separate cap for this. Allow the engine to reach operating temperature.
Wait for the thermostat to open, which may take 5 to 15 minutes. If you don’t have a funnel to seal the radiator, the coolant will leak out to the bottom.
14) Pay attention to the temperature readings
The next time you travel, pay attention to the temperature readings. The gauge should stay near the center, as it does when the vehicle is running at operating temperature. If the temperature rises to a high temperature, turn off the vehicle. Make sure there are no air pockets in the cooling system.
15) Check the coolant level
It is not uncommon to find a small amount of air trapped in the cooling system, even after bleeding the system. This air should release naturally over the next few trips.