What is a thermostat and how to check it?

What is a thermostat? When the engine is running, not only the energy of the torque is released, but also the heat. To ensure that the engine does not overheat and operate in its mode, a cooling system is provided. It consists of a water pump, which is driven by a pulley, a radiator (often two or three-section), nozzles and many other elements. An important component in the design of the system is the thermostat. What is it and how to check it, we will tell in our today's article.

Appointment

So, what is a thermostat? This is a structural element of the cooling system, designed to control the flow of coolant (coolant) during operation of the engine. As you know, the car uses two circuits - small and large. First, the liquid circulates through the first circle. Then, when the motor warms up to optimum temperatures, the valve opens, and the antifreeze goes already along the large contour. It is in the quality of the valve that the thermostat acts.

Where is

What is the thermostat, a little figured out. Now you need to find out the location of this element. Typically, the thermostat housing can be seen at the inlet of the pump or at the outlet of the cylinder head.

Device

This mechanism consists of several elements:

• Valve bodies;
• A return spring;
• Bottom and top frames;
• Stock;
• Valve discs;
• Rubber cavity;
• O-ring;
• The directing device;
• Thermoelement.

The latter is a kind of thermostat sensor. The increase in temperature is reflected in its consistency, which allows the valve to change its position. On modern cars, thermostats with a solid filler are used. Thus, the thermostat is a heat-sensitive mechanical valve. It is in a brass frame. The element plate is mounted on the thermostat housing.

What does this detail represent? It acts as a cylinder, inside which there is a rod that abuts against the rubber cavity on one side and into the frame on the other. The thermocouple itself is located between the body and the rubber cavity. The filler is a mixture of copper and granulated wax.

How does it work

When the engine is started, this valve is in the closed position. Coolant moves around a small circle, bypassing the main radiator. Thus, the engine is warmed up quickly. As soon as the temperature of the antifreeze reaches the preset parameters (about 80 degrees), the thermocouple begins to melt. So, the thermostat body moves on the rod. The plate begins to overcome the force of the return spring. Access to the large circuit of the cooling system opens. Note that the valve does not open immediately, but gradually. Thus, a uniform transition of fluid from one circle to the second occurs. Completely thermostat opens only at 95 degrees or more. When the engine is muffled, the temperature of the liquid drops. Accordingly, the thermoelement begins to acquire a solid state. This process is cyclical and repeated many times.

About temperature mode

The temperature of opening the thermostat can be different. Usually it fluctuates in a mode from 70 to 85 degrees. There are winter and summer elements. In the first case, the temperature of the thermostat (when it opens) is 82 degrees, in the second - 72 (as an example - the car "GAZelle" with the engine ZMZ). Experienced motorists recommend changing this element seasonally, so as not to subject the machine to overheating. But this trend is observed only on domestic cars. Foreign cars are designed for a more flexible temperature range. They can not change the thermostat to "winter" or "summer". But if the machine experiences overheating, it is still worth thinking about replacing it with a lower-temperature element. Sometimes the valve may not work at all. Therefore, below, we will look at how to check the thermostat yourself.

Workability Test - Method # 1

To ensure that this element is working properly, start the engine and warm it up to operating temperatures. Next, you need to open the hood and check to see how heated the lower and upper nozzles that go to the radiator. But here it is worth noting two nuances:

• The tubes can be very hot. Therefore, we only touch them through dense gloves.
• In order not to injure the hand about the fan (especially if it is not electric, but driven by viscous coupling), we check it on the muffled motor.

If both nipples are hot after a thorough warm-up, then the element is sound and does not need replacing.

How to check the thermostat? Method number 2

It should be noted that in the previous method there is a risk of overheating the motor. If the liquid does not enter the main radiator, it will heat up in seconds. In addition, the element can jam in one position. It is particularly problematic to identify a fault if the valve is only half open. So, the motor will be cooled and warmed up, but very long. The manufacturer does not give the rules for the warm-up time of the motor. This parameter is purely individual for each climate and air temperature. Therefore, for more accurate data, we remove the element outside and carry it into the house in the kitchen. Fill the water in a saucepan (you can take a small one), place the thermostat there and put it on the stove. As soon as the water began to bubble, we carefully monitor the opening of the valve. The spring must move smoothly. If this did not happen, then the element jammed.

Is it subject to repair?

The thermostat housing is not folding. Therefore, in case of failure, the part changes entirely to a new one. Fortunately, the cost of the element is no more than 200 rubles (for domestic VAZs).

So, we found out what the thermostat is, how it works and how to check it.