Thermostat - signs of malfunction and ways to solve the problem

Any engine requires cooling during operation. For this purpose, the unit has special channels, and the outside is provided with a thermostat. The whole system is connected by branch pipes. The coolant circulation is provided by a special water pump. In the people it is called a pomp. But not all. In order for the motor to warm up quickly, some of the liquid is forcibly "cut off" and does not circulate for a certain time. To control the coolant flows, a thermostat is used. The signs of his malfunction and the device are in our article.

Characteristic

What is this element? The thermostat is a small valve that is responsible for the operation of the cooling system. The device performs the function of automatic transmission of coolant flows with different temperatures.

How it works?

In any engine, two circuits are used:

• Small.
• Big.

In both there is a cooling liquid. However, after the start of the engine, it is heated only by the "small" circle. So the motor will quickly gain its operating temperature, which, as is known, is 80-90 degrees Celsius. A small circle is a heat exchanger for the stove and the motor itself. The second circuit includes a radiator with nozzles, which has a large cooling area. This radiator is located in front of the engine. In addition, the air intake is provided by a special impeller. It can be viscous, or an electric fan. But the operation of these elements is no longer dependent on the thermostat (here a temperature sensor or a crankshaft drive belt is used). What happens at this time with the thermostat itself? When the engine is started, this valve is closed. Inside the thermostat there is a heat-sensitive wax. As the temperature of the coolant increases, it begins to increase in volume. Thus, the wax squeezes the rubber chamber. The latter starts to push out the chrome plated metal rod, which puts the valve into operation. When the temperature reaches 70-80 degrees (each manufacturer has its own figures in this range), the thermostat opens. The fluid circulates in full circle over a large circle, getting into the radiator. As soon as the temperature decreases (for example, when the engine is muffled), the valve closes under the action of the return spring. This happens all mechanically, without the use of electronics.

As you can see, the device has a simple principle of operation. However, this mechanism sometimes fails. Symptoms of a malfunction of the thermostat, on the "Renault Logan" installed, are always accompanied by overheating. But first things first. So, below we will consider the main symptoms and signs of the thermostat malfunction.

Logan 1.6 has a copper thermostat. Its service life is quite large (10 years or more). But with its malfunctions, do not hesitate to replace it.

How to determine the breakdown?

Since the valve is responsible for the operation of the cooling system, the circulation of the liquid through the circuits will be disturbed. Often the thermostat jams in the closed state. Because of this, the antifreeze will not cool to the full even when reaching a 90-degree temperature. As a result, the motor will overheat. As a rule, after this, the geometry of the head of the block is violated. Repair such cylinder head is not subject to - only replacement. Therefore, do not ignore the temperature sensor.

What if the engine grabbed the "overheating"?

First of all, it is necessary to muffle the engine. Open the bonnet and allow the motor to cool. Do not cool it by force, by pouring water. This will lead to cracks in the block or head. Also, do not open the expansion tank cap - it can fire. Wait until the motor cools down. You can reach the place of repair by tow or tow truck.

The motor does not warm up to operating temperatures

Strangely enough, but these are also frequent signs of malfunction of the thermostat. "Kalina" is also subject to this phenomenon. If the valve jams in the open position, the liquid is constantly circulating in a large circle. The machine will take a long time to warm up.

Even on the move, the engine temperature will not exceed 60 degrees. As you can see, overheating is not the main signs of the thermostat malfunction. VAZ classic models is not the exception. The motor should work in its range. Otherwise, the viscosity of the oil changes, the properties of the film and the gaps on the valves. The engine is subjected to increased loads.

Why does this happen?

For what reasons is the thermostat broken? Symptoms of failure are often caused by a violation of the integrity of the structure. Since wax is placed inside the body, it flows out and mixes with the cooling liquid. Infringement of tightness occurs because of a poor-quality antifreeze or untimely replacement. As a result, the system undergoes corrosion processes. The tubes inside and also the thermostat begin to rust. Due to corrosion, the frictional force of the movable rod increases. Because of what else is the work of such a device as a thermostat disrupted? Symptoms of a malfunction may be caused by frequent and long engine warm-ups. To bring the motor to operating temperatures, do not need to keep it on the "idle" for 10 minutes. Some drivers and do advise to start the movement without warm-up, provided that the first 1-2 kilometers of the road will pass in a gentle mode (no more than two thousand revolutions). During this short period of time, the motor is able to warm up to operating temperatures. After the shooter has exceeded the mark of 70, you can start full-fledged operation.

How to check without removing from the engine?

Whatever the symptoms of the thermostat malfunction, it can be checked "in place" without removing it from the motor. So, start the engine and wait until the arrow starts to move on the scale (often it starts at 40 degrees). Next, open the hood and feel the upper and lower branches of the radiator. If the bottom element became warm almost immediately (before the arrow started moving), then the thermostat jammed in the open position. When the device is permanently closed, you will see how the arrow begins to actively "creep" up. This indicates a lack of cooling, for which the radiator is responsible. But access to it in the system, alas, is closed. The lower branch pipe will remain cold even when the temperature crosses the threshold of 90 degrees.

Check with dismantling

For more accurate diagnosis, remove the element from the car and put it in a pan, previously filled with water. The latter will simulate our antifreeze. So, install the tank on the gas burner and boil the water. We carefully look at the thermostat. As soon as the water starts bubbling, the serviceable element will open the valve. You will see how it will grow in size. If this did not happen, and the water is already boiling, then the device jammed.

About repair

The thermostat is an irreplaceable element. It changes entirely to a new one. The cost of the thermostat is not too high, even for foreign cars. The price rarely exceeds the threshold of 800 rubles.

Conclusion

So, we found out what the thermostat has the signs of a malfunction. Timely elimination of breakdowns is the guarantee of a long and trouble-free operation of your engine.