What is a thermostat? When the engine is running, not only torque energy is released, but also heat. To prevent the motor from overheating and working 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 sections), pipes 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.
Destination
So what is a thermostat? This is a structural element of the cooling system, designed to control the flow of coolant (coolant) during engine operation. As you know, the car uses two circuits - small and large.
First, the liquid circulates in the first circle. Then, when the engine warms up to optimal temperatures, the valveopens, and antifreeze goes already along a large contour. The thermostat acts as a valve.
Where is it
What is a thermostat, figured it out a bit. Now we need to find out the location of this element. You can usually see the thermostat housing at the pump inlet or cylinder head outlet.
Device
This mechanism consists of several elements:
- valve body;
- return spring;
- bottom and top frames;
- stock;
- valve discs;
- rubber cavity;
- O-ring;
- guide device;
- thermocouple.
The latter is a kind of thermostat sensor. An increase in temperature is reflected in its consistency, which allows the valve to change its position. Modern cars use solid-fill thermostats.
Thus, a thermostat is a heat-sensitive mechanical valve. It is in a brass frame. The element plate is pushed onto the thermostat housing.
What is this part? It acts as a cylinder, inside of which there is a rod resting against a rubber cavity on one side and against a frame on the other. The thermoelement itself is located between the housing and the rubber cavity. The filler is a mixture of copper and granular wax.
How it works
When starting the engine, this valve is in the closed position. The coolant moves in a small circle, bypassing the main radiator. In this waythe engine warms up quickly. As soon as the antifreeze temperature reaches the specified parameters (about 80 degrees), the thermoelement begins to melt. So, the thermostat housing moves along the stem. The plate begins to overcome the force of the return spring. Opens access to a large circuit of the cooling system. Note that the valve does not open immediately, but gradually. Thus, there is a uniform transition of the liquid from one circle to the second. The thermostat opens fully only at 95 degrees or more.
When the engine is turned off, the fluid temperature drops. Accordingly, the thermoelement begins to acquire a solid state. This process is cyclic and repeats many times.
About the temperature regime
The opening temperature of the thermostat may vary. Usually it fluctuates in the mode from 70 to 85 degrees. Distinguish between 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, a GAZelle car with a ZMZ engine). Experienced motorists recommend changing this element seasonally so as not to overheat the car.
But this trend is observed only on domestic cars. Foreign cars are designed for a more flexible temperature range. In them, you can not change the thermostat to "winter" or "summer". But if the machine experiences overheating, it is still worth considering replacing with a lower temperature element. Sometimes the valve may not work at all. Therefore, below we will consider howcheck the thermostat yourself.
Checking performance - method 1
To make sure that this element is working, you should start the engine and warm it up to operating temperatures. Next, you need to open the hood and check how hot the lower and upper pipes that go to the radiator are. But here it is worth noting two nuances:
- Tubes can be very hot. Therefore, we touch them only through thick gloves.
- In order not to injure your hand on the fan (especially if it is not electric, but is driven by a viscous coupling), we do the test with the engine turned off.
If both pipes are hot after a thorough warm-up, then the element is OK and does not need to be replaced.
How to check the thermostat? Method 2
It should be noted that in the previous method there is a risk of overheating the motor. If the liquid does not flow into the main radiator, it will heat up in a matter of seconds. In addition, the element may jam in one position.
It is especially problematic to identify a malfunction if the valve is only half open. So, the motor will cool and warm up, but for a very long time. The manufacturer itself does not give regulations on the warm-up time of the engine. 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 to the kitchen. Pour water into a saucepan (you can take a small one), put the thermostat there and put it on the stove. As soon as the water begins to bubble, carefully monitor the opening of the valve. The spring should move smoothly. If this does not happen, then the element is jammed.
Repairable?
The thermostat housing is non-separable. Therefore, in the event of failure, the part is replaced entirely with a new one. Fortunately, the cost of the element is not more than 200 rubles (for domestic VAZs).
So we figured out what a thermostat is, how it works and how to test it.
