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 own 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), 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 engine operation. As you know, a car uses two circuits - small and large.
First, the fluid circulates in the first circle. Then, when the engine warms up to optimal temperatures, the valve opens, and the antifreeze is already on a large circuit. It is the valve that acts as a thermostat.
Where is
What is a thermostat, a little understood. 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 body;
- return spring;
- lower and upper 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. On modern cars, solid-filled thermostats 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 part represent? It acts as a cylinder, inside which there is a rod abutting against a rubber cavity on one side and in a frame on the other. The thermocouple itself is located between the body and the rubber cavity. The filler is a mixture of copper and granular wax.
How does it work
When starting the engine, this valve is in the closed position. The coolant moves in a small circle, bypassing the main radiator. This ensures quick warming up of the engine. As soon as the antifreeze temperature reaches the set parameters (about 80 degrees), the thermocouple begins to melt. So, the thermostat housing moves along the stem. The plate begins to overcome the force of the return spring. Provides access to a large circuit cooling system. Note that the valve does not open immediately, but gradually. Thus, a uniform transition of fluid from one circle to the second occurs. Fully thermostat opens only at 95 degrees or more.
When the engine shuts off, the temperature of the liquid drops. Accordingly, the thermocouple begins to acquire a solid state. This process is cyclical and is repeated many times.
About temperature
The opening temperature of the thermostat may be different. Usually it ranges 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 expose the car to overheating.
But this trend is observed only on domestic cars. Foreign cars are designed for a more flexible temperature range. You can not change the thermostat to “winter” or “summer” in them. But if the machine is overheating, you should still consider replacing it with a lower-temperature element. Sometimes the valve may not work at all. Therefore, below we will consider how to check the thermostat yourself.
Health check - method number 1
To make sure that this element is working, start the engine and warm it up to operating temperatures. Next, you need to open the hood and check how heated the lower and upper pipes that go to the radiator. But here it is worth noting two nuances:
- Tubes can be very hot. Therefore, we touch them only through tight gloves.
- In order not to hurt your hand on the fan (especially if it is not electric, but driven by a viscous coupling), we do the check on a drowned motor.
If both pipes are hot after thorough heating, the element is in good condition and does not need to be replaced.
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 fluid does not flow into the main radiator, it will heat up in a matter of seconds. In addition, the element can jam in one position.
It is especially problematic to detect 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 himself does not give a regulation on the time of warming up the motor. This parameter is strictly 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 the pan (you can take a small one), put the thermostat there and put on the stove. As soon as the water begins to bubble, we carefully monitor the opening of the valve. The spring should move smoothly. If this does not happen, then the element is jammed.
Is it repairable?
The thermostat housing is non-separable. Therefore, in case of failure, the part changes entirely to a new one. Fortunately, the cost of an element is not more than 200 rubles (for domestic VAZs).
So, we found out what a thermostat is, how it works and how to check it.