Car thermostat: operating principle and main malfunctions

About the thermostat

The main task of the thermostat is to maintain the temperature of the coolant within acceptable conditions. The normal operating temperature of antifreeze in a VAZ 2114 is 85⁰±5⁰С. A working thermostat maintains this temperature in almost any weather conditions.

What does a thermostat consist of?

The thermostat kit includes several parts that are responsible for its operation. Below is a picture of the thermostat and a description of its components.

Thermostat operating principle

The operation of the thermostat is quite simple; it is not a complex mechanism. A special thermoelement (valve) is placed inside the thermostat, which opens or closes when the temperature of the liquid changes, and circulates the liquid in a large or small circle depending on the coolant temperature.

Step-by-step operating principle of a thermostat

1. During a cold start of the internal combustion engine (after an overnight stay), the fluid temperature is much lower than the opening temperature of the thermostat, therefore, the thermostat valve is closed.
2. When the thermostat valve is closed, the liquid circulates in a small circle, bypassing the cooling radiator. A small circle will allow the internal combustion engine to warm up to operating temperature much faster.
3. As soon as the temperature reaches 85⁰C, the valve opens and circulation occurs in a large circle through the cooling radiator.
4. As soon as the liquid temperature reaches 94⁰C, the valve on the thermostat opens completely and the engine cooling fan turns on. This can be seen while standing in a traffic jam.

We replace the thermostat on a VAZ-2115 ourselves

According to experts, the procedure for replacing a thermostat takes about an hour if tools and consumables are available. Therefore, you should take care of this before carrying out this operation. You will need the following:

1. Tools:
   standard car mechanic kit (screwdrivers of various sizes and configurations);
2. capacity of more than 7 liters for draining liquid waste.
3. Materials:
   new thermostat;
4. heat-resistant sealant;
5. set of gaskets for repair;
6. antifreeze or antifreeze (as a coolant).

Now you can begin the procedure for replacing the failed thermostat element, which consists of the following steps.

1. Preliminary – stage of preparing the vehicle for the repair procedure:
   the car is installed on an inspection hole or on a flat surface;
2. the engine is turned off;
3. put on the handbrake;
4. the engine is cold.
5. Removing the old thermostat element:
   unscrew the expansion tank cap;
6. open the radiator tap to drain the coolant from it;
7. drain the coolant into a prepared container;
8. remove the air filter (at the same time carry out a visual inspection for any malfunctions of this part);
9. loosen the clamps of the radiator pipes;
10. disconnect the hoses from the radiator and from the thermostat element;
11. unscrew the fastening bolts (4 pieces);
12. remove the thermostat (it is removed together with the seal ring).
13. Installation of a new thermostat:
    lubricate the perimeter of the circuit with heat-resistant sealant;
14. install a new sealing ring;
15. put a new gasket;
16. install a new thermostat;
17. connect all hoses;
18. tighten the clamps tightly;
19. screw the plug on the drain valve at the bottom of the radiator;
20. fill with coolant.
21. Verification stage:
    start the vehicle;
22. check for possible leaks;
23. warm up the car to the optimal temperature - more than 90 degrees (this operation is necessary for the large circle of the cooling system to start);
24. We check all hoses and pipes in operating mode - they should be hot.

A nuance of a working thermostat on a VAZ-2115: when starting a still cold engine, the lower pipe on the radiator will begin to heat up already at 85 degrees of coolant. This can be determined by touch.

To fully ensure that the newly installed thermostat element is functioning at the proper level, you should also turn on the heating element - the stove. If there are no failures or leaks in this mode, then the thermostat is installed correctly and without errors.

If you are not confident in your abilities, then to replace this part you should seek help from qualified specialists, that is, to the nearest car service center.

Where is

The VAZ 2114 thermostat is located under the air filter housing and is attached to the GCU on two studs through a sealing gasket. Easier access to the thermostat can be obtained by removing the air filter box.

When replacing a thermostat, there is no need to completely replace it. Most often, a thermocouple with a lid is replaced, but even here you can save money by buying only one thermocouple and placing it in the old lid.

Types of thermostats and rules for their selection

Having decided to replace the thermostatic device, many drivers are wondering whether to install an imported or domestic thermostat on a VAZ 2114, which one is better and which company to give preference to.

In this case, it is unlikely that it will be possible to give an absolutely accurate answer, because everyone chooses the appropriate spare parts themselves, based on the issue of availability, price and other factors.

Thermostat PEKAR

Let's say that we can distinguish the following 3 groups of thermostats that are suitable for the 14th and which can be found in regular car stores:

1. Domestic. Original thermostats for 2114 are very easy to find on sale, but it is worth remembering that their quality leaves much to be desired - they either fail ahead of schedule (25,000 km) or often jam, which can lead to overheating of the engine on the road. That is why it is not recommended to purchase them as a replacement.
2. Chinese. They may have an attractive appearance and a shiny body, but their overall quality is noticeably worse than domestic options. That is why you can purchase Chinese thermostats only if there is nothing else left.
3. Foreign. Despite the slightly higher cost, they have much better quality of workmanship, which is why preference should be given to them.

Thermostat LUZAR

But what to do if you couldn’t find branded parts, but the choice of thermostats themselves is quite wide and the prices are about the same? In such a situation, you should pay attention to the material of the case. You should only purchase products made from stainless steel or high-quality brass, which can be distinguished by weight by holding them in your hands.

WEEN thermostat (Poland)

You should absolutely not purchase products made from zinc alloys, which can imitate brass or steel, but are also very light. The housings of such thermostats are extremely unreliable and can leak not only from impact, but also from frequent temperature changes (especially in winter).

Examination

The check can be carried out in one simple and proven way. To do this, you will need to start a cold car, it would be best after an evening standstill. After starting the internal combustion engine, as soon as the coolant reaches a temperature of 70⁰C, you need to touch the pipe of the large antifreeze circulation circle. It is the lowest radiator pipe. This pipe should be cold until the car reaches 85⁰C.

The pipe indicated by the red arrow must be cold

If the pipe heats up along with the others or already begins to feel warm at 70⁰C, then the thermostat is faulty and requires replacement.

How to check the thermostat operation

In fact, there is nothing easier than to independently diagnose a thermostat malfunction. You can do this without even removing it. The main requirement is a cold engine.

A serviceable device on a cold engine is in a closed state. As we remember, the melting point of wax is 80-82 degrees. Until the engine temperature reaches a set point, the pipes leading to and from the radiator (as well as the radiator itself) must remain cold.

If after just a few minutes of engine operation they become warm, we can conclude that the thermostat is stuck open.

The situation is exactly the opposite: the engine has heated up over 90 degrees, but the large circle pipes remain cold. This also indicates that the thermostat is faulty and cannot open. Circulating only through a small circuit, the antifreeze quickly heats up, and it is no longer able to provide proper cooling of the engine.

In both cases it is necessary to replace it. There is another way to check the thermostat. To do this, the device must be removed, observing all safety precautions. We have already written a detailed article about removal and replacement.

The essence of the testing method is as follows: the device is placed in a pan with cold water and a thermometer. It is important that the thermostat does not touch the walls and bottom of the pan; for this it is best to hang it. After this, we observe at what temperature the valve begins to open.

This method seems unnecessary to the author, since it will not be possible to accurately determine the response range in this way, and this will obviously add more work.

Replacement

Replacing the thermostat is a fairly simple job that every owner of a VAZ 2114 can do; you just need to prepare the necessary tools.

To replace you will need:

• Container for draining antifreeze;
• Funnel with hose for draining antifreeze;
• Set of keys and hexagons;
• Sealant;

Replacement instructions

• We remove the air filter housing by loosening the clamp securing the corrugation to the air flow sensor and unscrewing the fastenings of the box to the “TV”;

• Drain the coolant through the drain hole in the block by unscrewing the plug with a 13mm wrench;

• Loosen the thermostat cover clamp and remove the two pipes;

• Unscrew the three bolts securing the cover to the thermostat body and remove it;

• Installing a new thermostat;

• If the pipes are old and rather hard, it is recommended to secure them with sealant to avoid coolant drips;

• We tighten the coolant drain plug in the block and fill the coolant into the expansion tank;

• We warm up the car to operating temperature and check the coolant level; if necessary, top it up;

The thermostat replacement is complete.

Thermostat replacement algorithm

To carry out repair work, the following operations are required:

• drain the coolant - to do this, you must open the cap of the expansion tank to prevent a vacuum zone and only then unscrew the drain plug (do not forget to substitute a 10-liter container);
• disconnect the temperature sensor and remove the ground wire so as not to damage the electrical wiring, injector, generator and other important devices;
• loosen the fastening clamps and unscrew the fixing nuts, then, using oscillatory movements, release the thermostat from the pipes;
• installation of a new device is carried out in the reverse order; first check the condition of the hoses and, if necessary, replace them;
• Clean the mounting location and install a new gasket, after which you can install a new VAZ 2114 thermostat (injector);
• After filling the coolant, you need to make sure that it passes normally through all working circuits and that there are no air pockets in the system.

Recently, it has become fashionable to install a Granta thermostat on the VAZ 2114, which is a low-temperature device and operates at 65ºC. As a result of such a replacement, the transfer of coolant to movement along a large circuit occurs earlier, as a result of which the thermal wear of engine parts and components is reduced. Also, when installing a control device from Granta, the operation of the interior heating stove improves.

When purchasing this spare part, please make sure by all available means that the device is unique and new, so as not to end up with a restored faulty thermostat. Purchase important mechanisms only from trusted sellers with a long and well-deserved reputation.

What is a thermostat?

As the name of the device suggests, it does something with temperature. More specifically, it helps switch fluid flows in the cooling system. Moreover, the thermostat, carburetor or injector are at the heart of the gasoline injection system and have the same composition and housing design. When operating any engine, it is necessary to ensure heating of the throttle assembly. And it is present in any injection system: both in the carburetor and in the injector.

The basis of any thermostat is a special plate, which is made of a material called bimetal. It reacts to temperature changes and is capable of deformation because of this. The switching of air flows is based on this effect: the plate moves the valve, which is fixed by springs. Having overcome their force, the plate moves the valve, opening the path for liquid flow to the main radiator to ensure effective cooling.