How To Change Car Thermostat

How To Change Car Thermostat – DIY without being a car mechanic

When a Car Thermostat Begins to Fail – What Should You Do?

So, you might be wondering how will you figure out that your car’s thermostat is damaged and needs a replacement. The answer to this is – easy as pie. You don’t need to be a professional mechanic to learn how to change a car thermostat.

First of all, you will notice that after you start your car’s engine, the temperature will quickly be high as per indicated by the temperature gauge. Not only is quickly reaching high temperature above normal is an indicator, but also taking excessively long to warm up the engine. This is the time when you know that you need immediate thermostat replacement.

Do not know how to change your own car’s thermostat? Do not worry. You have ended up exactly where you should be. In this article and the upcoming sections, we will discuss and elaborate how to change car thermostat.

Before we dig in, we shall talk about other necessary topics too before you get started and tell you how to change your car’s thermostat.

Firstly, we will tell you where it is exactly located to know where you should be searching, how long will it take you to replace your car’s thermostat and what to do after replacing your car’s thermostat. 

Enough talking! Let us dive right into our mission and get started.

Where Is The Thermostat Located?

Well, a lot of cars have their thermostat located close to the water pump on the top of the cylinder head. The thermostat’s housing, in many cars, is mostly attached directly to the upper hose of the radiator. Meanwhile on the other hand, the thermostat’s housing is attached to the bottom hose of the radiator.

Which Way Does A Thermostat Face?

The thermostat is a bimetal strip. That is, it is made of two metal strips. These are not welded as one piece but rather joined together. These are mostly iron and brass. Metals expand at different rates when heated. Brass stretches or ‘expands’ more than Iron. Due to different expansion rates, the strip will bend inwards.

You will notice that there is spring in one of the ends of the thermostat. This side, with the spring, will be facing the engine. The other side, with no spring, and kind of pointed, will be facing the hose of the radiator.

How Long Does It Take To Replace A Car Thermostat?

The answer to this has no accurate time because it really depends on your car’s model, type and year it was made in. However, it usually should not consume a lot of time, perhaps around twenty to half an hour in most cases unless otherwise you have a car with a non common design. That is when it might take to more than an hour.

How To Change Car Thermostat 

Step one – Check Your Thermostat

Make sure your car is cool. Next, start the engine. Carefully use your hands to check the radiator’s upper hose temperature. 

If there are no issues with the thermostat, the upper hose should not heat up rapidly and will take some time. However, if the upper hose does not rise in temperature but the engine does get quickly heated, then the thermostat is closed. 

On the other hand, if the upper hose rapidly heats up, then the thermostat is open. In either ways, it is stuck in either closed or open position for the prior mentioned scenarios.

Step two – Buy New Thermostat

It is quite important to get the same exact thermostat for your car because there are different standards. Check the number on your damaged thermostat.

Step three – Open The Upper Hose

Carefully disassemble the upper hose’s clip and gently remove the hose. Make sure your engine has cooled down and no temperature is too high to hurt you before you remove the hose. 

Step four – Empty Out Coolant From Radiator

To clear our any coolant, you should carefully disassemble the bottom hose to discharge the coolant until it is just beneath the level of the housing of the thermostat. 

Note: if you want to use the coolant again, then make sure you discharge it in a bottle with a filter on top and fill it back when you are done.

Step five – Removing Thermostat from Housing

Carefully remove the thermostat from housing after removing any bolts and nuts holding the housing in place.

Step six – Inserting New Thermostat

Prior to inserting the new thermostat, gently use a brush to remove any dirt and pieces from the old thermostat. Make sure the scraps do not fall inside. Then place the new thermostat in the same orientation that you found the old one. 

Do not forget to add back the coolant that you have collected in the bottle in step four. If necessary and you think that, the coolant is a bit dirty, its time you buy a new coolant. Because this too might be one of the reasons, your system is heating up quickly.

Step seven – Secure the Housing

Secure the thermostat housing by placing the nuts and bolts back in place.

What To Do After Changing Car Thermostat?

After finally doing your mission of replacing your car’s thermostat, keep your eyes open for any changes. If the problem still persists, you can go to the conclusion section below for the most two frequently asked questions post changing a car’s thermostat.


Now that you have changed your car’s thermostat, you might ask yourself two questions post to your mission. We address them below and discuss them.

After you are done you might be wondering – why is my car overheating after I changed the thermostat? This issue might arise when your radiator has issues. Your car’s radiator might be congested or filled with dirt or such. Having a congested radiator will make the coolant’s flow constricted, thus heating up the engine quite fast. Anyway, this is an easy fix. 

Then, when should I replace my thermostat? It is always a marvelous idea to think of replacing your thermostat when you are replacing or updating your climate control system. That is, when it comes to replacing or fixing HVAC system of your car, replace your thermostat too because they are all linked together.