Is Thermostat Part of Engine? (3 Impacts of Thermostat on Engine)

On a Joe Rogan’s podcast, I once heard him saying, how he loves the core mechanical grunts of classic vintage vehicles.

The very sound of those engines gave you an experience that was raw, real, and made you feel in control.

Gotta love Joe.

Well, I am using the Joe Rogan reference to make a point here. I don’t want to take it any further because before you know it, we may cross the border from tech into chimps and aliens.

So, the point being with time and evolving technology we have come far.

From vintage cars housing pure mechanical engines to this day where mechanical structures are fused with electrical systems.

We have hybrid engines where electronics are so closely knit with mechanical structures that it’s hard to think of one without the other.

But even without the automated electronic part, an engine unto itself is a fascinating entity.

I receive technical questions on engines and automobiles, in general, every day.

Today let me cover a very interesting one that brings in context engines and a very important aspect of its operation, engine cooling.

Is thermostat part of engine?

Well, it would be more justified to call a thermostat an integral part of the vehicle cooling system rather than the engine itself. With the help of a thermostat, a closed-loop coolant cycle is created that maintains an engine’s temperature at a certain value.

Was that too much? Well, engineers and people who have hands-on experience with vehicle engines may have decoded what I just relayed.

But you know, that is precisely why I chose to write on this topic.

Also, I do understand that many of you maybe asking this question because you want to know if you can change the thermostat by your own.

Well, as I said thermostat is part of the cooling system and if you follow the radiator hose that goes into the engine, for most cars, thermostat is the intersection of the radiator hose and the engine.

With the help of a wrench you can open up this junction and replace the faulty thermostat with a working one.

This is a video that I found that explains exactly how you can do that.

I think the context of the article is perfect to throw some light on different parts of an engine, different parts of a thermostat and why a thermostat is part of an engine’s cooling system.

To make your knowledge even more comprehensive, here are a few more related articles that you can choose to read after this one.

Different Parts of an Engine

Before we go ahead and discuss the different parts of a thermostat and where it comes in the picture of engine operation, let me quickly relay the different parts of an engine.

When I say quickly, I do know, that there are degrees around engines. I have had the experience of working in an automobile company and the sheer intricacy of engines and everything around it is just fascinating.

But just to make this article come together in a holistic sense, here are the different parts of an engine explained in brief.

parts of an engine (exploded view)
Parts of an Engine (Exploded View)

Broadly, this mechanism called engine can be divided into 13 main parts.

These are engine block (cylinder block), combustion chamber, crankshaft, camshaft, cylinder head, pistons, pushrods/lifters, fuel injectors, timing chain, valve train, valves, rocker arms, and spark plugs.

Here is a brief description of each of them.

  • Cylinder Block

Made out of aluminum alloy this is the core body of the engine. It houses the pistons in its cylinders (thus cylinder block). The more cylinders an engine has, the more powerful it is.

  • Combustion Chamber

In the combustion chamber, energy exchange takes place. This is where the explosive reaction of fuel, air, pressure, and electricity happens to make the pistons go up and down. This in effect transforms fuel energy into mechanical motion.

  • Cylinder Head

The cylinder head sits atop the engine cylinders and in addition to creating a space for combustion houses other engine parts like intake and outtake valves, spark plugs, and fuel injectors.

  • Pistons

The combustion process causes the piston to move up and down thereby effectively providing the vehicle the necessary power to move.

  • Crankshaft

The crankshaft is responsible for converting the linear motion of the pistons into rotational motion. It is connected to the camshaft using rubber belts which are in turn connected to the drive train that transfers the power to the wheels.

  • Camshaft

The camshaft works together with a crankshaft and with the help of a timing chain allows the intake and outtake valves to open and close.

  • Timing Chain

The camshaft and crankshaft are connected with the help of a timing chain. All of them work together in tandem to ensure certain actions take place just when they are meant to. This is paramount for the proper functioning of an engine.

  • The valvetrain

The valvetrain is responsible for the control of the movement of valves. It comprises of valves, lifters, push roads, and rocker arms.

  • The Valves

The intake valves allow the insertion of air and fuel into the combustion chamber. The outtake valves move away from the exhaust that is created as a result of the combustion process.

  • Rocker Arms

Rocker arms work in tandem with the camshaft to open and close the valve system to let air in or let the exhaust out.

  • Pushrods

Pushrods are these long metal rods whose function is to transfer motion from the camshaft to the valves to make them operate the way they should.

  • Fuel Injectors

As the name suggests, fuel injectors inject fuel into the combustion chamber for the combustion process to occur.

  • Spark Plugs

Spark plugs are set over each of the cylinders and initiate a park that is used to ignite the compressed fuel and air mixture thereby starting the explosive process that will make the vehicle come alive and move.

So, those were the major parts of the engine that you need to be aware of. Once again this is just touching the tip of the iceberg so to speak.

You can go into enormous details not just with the parts of the engine but also into each of these parts.

Doing so will deviate me from keeping true to the context of the article. But I felt a brief overview of what an engine is comprised of will help you understand the topic better.

Thermostat Parts and Functions

Now looking at the different parts of an engine you invariably have a frame of what an engine actually is in your mind.

You see an engine is unto itself a cluster of parts that work together to convert the energy from fuel into what we see as a moving vehicle.

So, an engine is the heart of your vehicle. But here is the thing an engine is not an independent entity.

In addition to the parts that we discussed here; it also needs other parts so as to extract the maximum output from the engine or to append its functioning.

These can be standalone parts like sensors that provide us data about the different parameters of an engine or they can be an entire mechanism like the cooling system.

You see for an engine to perform at its optimal capacity it needs a regulated environment so to speak.

The primary parameter that needs to be regulated is the engine temperature.

This task is done by the cooling system that comprises the radiator, the coolant, the motor, and of course the thermostat.

The thermostat is kind of like a mechanical switch that ensures a closed-loop path is provided to the coolant to keep the engine temperature at an optimal value.

If that didn’t make a lot of sense that’s fine, we will see the functioning of a thermostat in the next section.

For now, just have a look at what the thermostat looks like and what are its different parts.

parts of an automobile thermostat
Parts of a Thermostat

Here are the basic parts of a thermostat unit.

  • Structural frame

Also known as the housing of the thermostat and it contains a valve that is attached to the piston. It’s like a cage that holds all the parts together in a thermostat.

  • Flange

The flange is the small circular metal plate that you see around the core body of the thermostat. It may seem like an insignificant flat metal piece but it is vital in allowing coolant to flow without obstruction and in a regulated sense.

  • Spring

Spring in the thermostat is responsible for keeping the valve closed when the coolant is not hot enough. This enables the engine to achieve its optimum temperature faster.

  • Wax Element

The wax element plays a key role in allowing the coolant to pass through once a particular coolant temperature is reached. The wax is thermally expansive meaning upon reaching a certain temperature it melts and enables the valve to open giving way for the coolant to reach the radiator.

Function of a Thermostat in Cooling System

Well, I think if you have been following everything that we have discussed here, you will have a good sense of what makes an engine and how different elements come together to make the mechanism work.

Once again, the article isn’t meant to provide or go into intricate details about how an engine functions. But I do intend to give you an eagle’s eye view into the functionality so that you have a comprehensive understanding of the core topic of the article which is, is thermostat part of engine.  

Now that we know the parts of an engine and the parts of a thermostat, you will see that understanding the function of a thermostat will become very easy.

As a matter of fact, I have already written an article on whether thermostat is necessary in a vehicle at all.

I have gone into immense depth in that particular article with examples and test cases in different environmental conditions.

Here is a good video that I found that explains how exactly thermostat functions in a cooling system.

As you can see thermostat is the core element that helps create a feedback coolant loop because of which the engine stays at its optimal temperature.

This optimal temperature is decided by exposing the engine to a lot of test cycles in research facilities.

I have had the pleasure of being a part of such a research facility in my experience of working in a managerial capacity in an automobile manufacturing firm.

Now, of course, the optimal temperature differs with different vehicle systems but for cars that are mass-produced for the general public, the optimal temperature range is around 83°C to 92°C.

A thermostat functions like a switch that ensures that the engine remains at its healthy working temperature.

Operating Vehicle without a Thermostat

Now many people tend to ask the question what will happen if I remove the thermostat from my car?

For exactly that question I wrote this article on whether thermostat necessary in a car.

In that article, I go in-depth into explaining the exact mechanics behind what happens when you operate a car without a good high-quality thermostat.

Here is a quick rundown of the potential effects of an absent thermostat in your car.

  • Degradation in Engine Efficiency
  • Degradation in Fuel Economy
  • Improper functioning of ECU.

So how do these effects come about?

An absent or faulty thermostat will mean there is no gate between the engine and the cooling system. This means the coolant won’t stay with the engine helping it come to its optimal temperature faster.

This results in decreased engine efficiency of the car.

Moreover, the absence of a thermostat also leads to improper heat exchange between the engine body and the coolant. The coolant won’t stay in the engine channels to get hot enough and it won’t stay in the radiator to get cool enough.

This invariably leads to engine overheating.

Other effects are subtle in nature. See, as I said in a previous segment of this article, the temperature is not the only parameter that is assessed.

The Engine Control Unit monitors parameters like pressure, rpm, temperature, etc. from places like combustion chamber, exhaust, and catalytic converter to control various actions.

Now if the thermostat is faulty, the ECU will conclude that the engine isn’t hot enough and regulates the other parameters to make up for it.

This results in a degraded fuel economy of the vehicle.


So, there we have it. I hope you understood how the thermostat fits in in the entire scheme of things that is engine operation.

In order for the engine to operate in a way that is optimum for vehicle operation, its cooling system plays an important role of which the thermostat is an integral part of.

Now I am also aware of the fact that knowledge is also limited and doesn’t matter how comprehensive and insightful you make it, it will still miss out on something or the other.

Still from my side, I want to be as thorough as I can be. Here are a few more questions around the core question of is thermostat part of engine that people often ask.

What is the function of thermostat valve?

The thermostat valve allows the thermostat to act like a switch that opens up or closes as a direct function of temperature. It is because of this valve a closed coolant loop gets created that ensures that the engine always remains at its optimal temperature.

What Causes Thermostat to fail?

Thermostats are designed to last. Most experts agree that the average lifespan of a thermostat is around 10 years. But that is a very optimistic number.

There are many reasons that may cause the thermostat to malfunction or fail entirely.

Here are the most common ones.

  • Damage of wax element.
  • Choking (by the formation of slush and debris).
  • Wear and tear over time.
  • Overheating.
  • Inherent manufacturing defects.
  • Improper installation.

What are the symptoms of a faulty thermostat?

A faulty thermostat can lead to the development of a range of problems. In the immediate sense, your car will still run albeit with poorer engine efficiency and fuel economy.

Here are some symptoms of a faulty thermostat.

  • Initiation of ‘Check Engine’ light. (This may indicate some other problems as well but a faulty thermostat for sure will initiate it)
  • Continued high engine temperature.
  • Decreased fuel efficiency.
  • Coolant leak.
  • Inconsistent temperature changes.
  • Unusual engine noise.

I hope I was able to put forth a well-rounded knowledge base when it comes to the engine, thermostats, vehicle cooling system, and how it all comes together.

You see with every single article here on Yantraas, I use every single topic to create a knowledge base that touches everything that the context demands for a better understanding.

For that reason, sometimes the article gets bigger than what I wanted it to be. But at the end, I am satisfied with the fact that I didn’t skimp on something that needed to be done just to save some effort.

If you have any queries, comments, or feedback associated with anything that you just read, please let me know in the comments below.

Take care of yourselves and I will see you in the next one!


Electronics Engineer | Former Deputy Manager | Self-Taught Digital Marketer.Owner & Admin Of A Network Of Blogs and Global E-Commerce Stores

Pin It on Pinterest