Guide

Car thermostat

The thermostat is, alongside the water pump, the most important component of the engine cooling system and controls the flow of coolant to the radiator. Its main tasks are to efficiently cool and warm up the engine. Ensuring an optimal temperature has a beneficial impact on engine operation, fuel consumption, and the content of harmful compounds in exhaust gases. One of the most common failures is thermostat damage. A broken thermostat doesn’t close, leading to problems with reaching the optimal operating temperature of the engine, resulting in high fuel consumption. When the thermostat doesn’t open, there’s an uncontrolled increase in coolant temperature and engine overheating.

Topics covered in the article:

1. The role of the thermostat in a car engine
2. How does a car thermostat work? 
3. How long does a car thermostat last? 
4. Symptoms of a damaged car thermostat
5. How to check a car thermostat? 
6. How much does it cost to replace a car thermostat? 
7. How long does it take to replace a car thermostat?
8. How to vent the cooling system after replacing the thermostat? 

The Role of the Thermostat in a Car Engine

As mentioned in the introduction, the thermostat in a car is responsible for a few crucial functions:

• Temperature Control
  The thermostat regulates the flow of coolant through the engine’s cooling system. When the engine temperature is low, the thermostat closes, restricting the flow of coolant to the radiator, which helps the engine reach and maintain the proper operating temperature faster.
• Ensuring Optimal Operating Temperature
  The thermostat helps keep the engine at the optimal operating temperature. Too low a temperature can lead to low engine efficiency, increased fuel consumption, and higher emissions of harmful substances. Too high a temperature can lead to engine overheating, which can cause engine component damage.
• Limiting Fuel Consumption
  By maintaining the optimal operating temperature of the engine, the thermostat contributes to fuel savings. Engines operating at the right temperature are more efficient.
• Protection Against Overheating
  In case of thermostat failure or other cooling system component failure, the thermostat can be the last line of defense against engine overheating, as it can limit the flow of coolant, preventing the complete release of fluid and overheating of the engine.

In short, the thermostat in a car engine is a key element of the cooling system that helps maintain the engine at the right operating temperature, which translates to its efficiency, durability, and effectiveness.

How Does a Car Thermostat Work?

We know what the thermostat is responsible for. How does it work? The operation process of a thermostat is relatively simple:

1. Engine Warming: When the engine starts, the thermostat is closed. This means that coolant cannot freely circulate through the cooling system, and the heat from the engine is not dissipated.
2. Thermostat Opening: When the engine warms up to a specific temperature (usually about 82-88°C), the thermostat opens, allowing the coolant to flow through the radiator.
3. Temperature Regulation: The thermostat acts like a valve, opening and closing in response to the temperature of the coolant. When the temperature of the coolant falls below a set value, the thermostat closes, restricting the flow of coolant and helping the engine quickly reach the right operating temperature.
4. Preventing Overheating: The thermostat also serves as a protection against engine overheating. If the engine temperature reaches too high a level, the thermostat can open completely to allow maximum coolant flow and cooling of the engine.

Thanks to this mechanism, the thermostat helps maintain the engine at the right operating temperature, which translates to its efficiency, durability, and effectiveness.

How Long Does a Car Thermostat Last?

The lifespan of a car thermostat can vary depending on many factors such as manufacturing quality, operating conditions, frequency of service, and the environment in which the vehicle is used.

Under ideal conditions and with regular servicing, a car thermostat can last for many years without needing replacement. However, certain factors can affect the longevity of the thermostat. Driving in extreme conditions, such as high temperatures, intense engine loads, or rough terrain, can accelerate thermostat wear. Lower-quality thermostats may be less durable and prone to failure compared to branded or original parts. Deposits and contaminants in the cooling system can affect the operation of the thermostat and accelerate its wear. Engines may be prone to shocks and vibrations, which can lead to damage to the thermostat or its seals.

It is recommended to regularly check the condition of the cooling system during routine service inspections, which will allow early identification of potential thermostat problems and avoid more serious engine damage. In case of symptoms of thermostat failure, such as unstable engine temperature or heating problems, it is advisable to replace the thermostat as soon as possible to prevent engine damage.

Symptoms of a Damaged Car Thermostat

Here are some symptoms that may indicate a damaged thermostat in a car engine:

• Low or unstable engine temperatures: If the thermostat is damaged or stuck in the open position, the engine may have difficulty reaching the right operating temperature. This can lead to unstable engine temperature or operation at lower than normal levels.
• High engine temperature: Thermostat failure can also lead to engine overheating. If the thermostat is damaged and stuck in the closed position, coolant will not be able to freely circulate through the cooling system, leading to heat buildup and engine overheating.
• Heating problems inside the vehicle: A damaged thermostat can also affect the operation of the vehicle’s heating system. If the thermostat is damaged, coolant may not circulate properly through the heating system, resulting in weak or no heat inside the vehicle.
• High fuel consumption: A malfunctioning thermostat can lead to low engine efficiency, which can in turn increase fuel consumption. If the engine operates at a lower than normal temperature, it may be less efficient, requiring more fuel to achieve the required power level.
• White smoke emission from the exhaust pipe: A damaged thermostat can also lead to cooling system failure, which can cause coolant leaks into the combustion chamber. This can result in white smoke emission from the exhaust pipe.

It’s important to note that these symptoms of a damaged thermostat can also be caused by other problems in the cooling system or engine. In case any of these symptoms occur, it is recommended to consult a mechanic who can accurately diagnose the problem and carry out the repair.

How to Check a Car Thermostat?

Checking the thermostat in a car with home methods can be challenging, but there are a few simple techniques that can give some indications of its condition. Let’s list a few ways to check the thermostat in a car:

• Observation of the temperature gauge
  If the engine temperature gauge shows very low temperature, rises slightly or does not reach the optimal operating temperature, it may suggest a problem with the thermostat. However, the temperature gauge can also be affected by other problems in the cooling system, so this test is not absolutely reliable.
• Car interior heating
  If there is no heat inside the car or the heating is weak, it may indicate problems with the thermostat or cooling system.
• Radiator examination
  After warming up the engine, touch the radiator (carefully, to avoid burns). If the radiator is cold, it may mean that the thermostat is closed and does not allow coolant to pass. However, remember that the radiator can be cold due to other problems in the cooling system.
• Checking coolant flow
  In some cases, you can remove a hose from the radiator, connect it to a bucket, and start the engine. If the coolant does not flow when the engine heats up, it may indicate a problem with the thermostat. However, this test is quite advanced and requires caution.
• Reading error codes from the car computer
  In some modern cars, a problem with the thermostat can be detected by reading error codes from the car computer using a diagnostic device.

It is important to remember, however, that these methods can only give hints, and accurate diagnosis of thermostat problems usually requires a visit to a professional car mechanic. If you suspect a problem with the thermostat, it is best to consult an experienced mechanic.

How Much Does It Cost to Replace a Car Thermostat?

The cost of replacing a car thermostat in Poland in 2024 can vary and depends on several factors such as the make and model of the car, the type of thermostat, the region of the country, and the individual pricing policy of the car workshop.

In the case of a typical thermostat replacement in a passenger car, the cost can range from about 100 to 500 zł. However, if additional repairs are required or if the thermostat is part of a cooling system that requires comprehensive maintenance, the costs can be higher.

It’s also worth adding that the price of spare parts, the quality of the thermostat, and the price of labor can vary significantly depending on the location and the reputation and experience of the car workshop. Therefore, it is always a good idea to consult several workshops to get a quote and choose the option that best suits the needs and budget of the customer.

How Long Does It Take to Replace a Car Thermostat?

Replacing a thermostat in a car usually takes about 1 to 2 hours of work for an experienced car mechanic in a well-equipped workshop. The procedure for replacing a thermostat usually includes several steps, such as draining the cooling system, removing the cover and external elements, removing the old thermostat, cleaning the mounting surface, installing a new thermostat, refilling with coolant, and checking the system for leaks. The replacement time can vary depending on access to the thermostat, its location in the engine, and any complications, such as rusted or damaged parts.

How to Vent the Cooling System After Replacing the Thermostat?

After replacing the thermostat in a car, it is recommended to vent the cooling system to ensure proper coolant flow and avoid the formation of air in the system, which can lead to engine overheating. Here are a few steps you can take to properly vent the cooling system:

1. Vehicle setup: Make sure the car is on a flat surface and its engine is completely cold.
2. Opening the coolant expansion tank cap: Locate the coolant expansion tank (usually located near the radiator) and carefully unscrew the cap.
3. Adding coolant: Add coolant to the tank until full. Make sure you use the appropriate type of coolant recommended by the vehicle manufacturer.
4. Running the engine at idle: Start the engine and leave it at idle for a few minutes. Allow the engine to heat up and the coolant to circulate through the cooling system.
5. Monitoring the coolant level: Monitor the coolant level in the expansion tank and top up if necessary.
6. Checking for air presence: During venting of the cooling system, pay attention to whether air is coming out of it. Air can be seen as bubbles in the coolant. Try to vent the cooling system until you see that the coolant is flowing without air.
7. Closing the expansion tank cap: After completing the venting process, close the expansion tank cap.

If you have doubts or difficulties in venting the cooling system, you can always consult an experienced car mechanic who will help you carry out this process correctly.