Do not confuse!


The thermostat is a simple device. But very important. Errors when replacing it are not allowed.


The thermostat in the engine is used to maintain the proper temperature in the cooling system. But its functions are not limited to this: power, fuel consumption, exhaust hazard, and heater operation efficiency depend on a simple device. And also - durability, engine life.

On all VAZ cars, the thermostat is removed from the head of the engine block and is an independent element. Today we know the following models:

2101 - all VAZ “classics” are equipped with such, starting with the first-born VAZ 2101. The valve begins to open at a temperature of 80 ± 2 °, and is fully open at 95 ± 2 °. A distinctive feature of the "first" thermostat - the pipes are deployed relative to each other at an angle of slightly more than 90 degrees (photo 1 on the left).

2121 - for the Niva. The filling is practically “zero first” thermostat. Only due to the layout features of its pipes are located on the body at an angle of almost 180 degrees. By the way, on the modernized Niva VAZ 2121 3 there is a thermostat 2101.

2108 - the next generation of thermostats (photo 1 in the center) - is intended for Samara engines. The latter have a more perfect shape of the combustion chamber and a higher compression ratio; their temperature regime is 7 ° higher compared to the classics. This improves the power and economic characteristics of the machine. The “eight” thermostat starts to open at 87 °, and it is fully open at 102 °. True, today there are “eighth” thermostats on the market with a valve opening temperature of 85 °. The explanation is simple: the quality of thermostats is now not up to par, the valve often opens with a delay, creating a risk of engine overheating. So they took off two degrees … "in reserve".

The nozzles of the thermostat 2108 are located almost as if they were on the “first zero, ” but as if mirror-like in relation to it. In addition, closer to the bottom of the "eighth" there is an additional thin pipe - for connecting to the expansion tank (see photo 1 in the center). This is the way to exit the air bubble cooling system if for some reason it gets there.

2110 - structurally repeats the "eight", it has almost the same characteristics (circulation in the "big circle" will begin at 87 or 85 °). Outwardly, it is even more similar (but also mirrored, not to be confused!) With “zero first”, since it does not have an additional thin pipe (photo 1, right).

On the VAZ 2110, a “road” for air was laid from a tee adjacent to the thermostat. The latter is intended for cars with carburetor engines (VAZ 2110 and 21111). If necessary, they can also be equipped with a “eight” thermostat, you just need to thoroughly drown out its air pipe.

It happens that the manufacturers of these products arbitrarily simplify the design, so when buying a thermostat, look into it. In the upper part of the body there should be a vertical strip of metal or plastic, resembling a curtain, which covers an additional valve in a sector of approximately 270 ° (photo 2). Without this shutter, the liquid mixes worse, heats the thermo-power element less and slower - and the thermostat switches to the “big circle” with a delay at elevated temperatures.

2112 - the next generation thermostat - for injection engines (photo 3). It differs from the previous ones in that, in addition to the main function, it also increases the efficiency of the heater. To this end, he increased the resistance of the "small circle", thereby forcing the coolant to flow more intensively through the radiator of the heater. This thermostat has an orifice in the inlet. The transition from "small" to "big circle" begins at a temperature of 85 °. By the way, the temperature threshold for the start of operation of any thermostat is squeezed out on the bottom (photo 4).

We now turn to the sensor (photo 5) for turning on the electric fan of the cooling system. Today, two generations of sensors are produced - two-ampere and twenty-ampere. Moreover, each, in turn, is divided into two categories - for the classic and front-wheel drive models.

The first generation includes TM-108 veteran sensors. Since they could not directly commute a large current, this role was assigned to a special power relay, which was triggered by a command from the sensor. For classics, this sensor had an index of 2103-3808800. Recall: "treshka" was the first VAZ car without a constantly rotating mechanical impeller. The temperature for turning on the fan is 92 °, and for turning it off - 87 °.

As already noted, the Samara engine has a more stringent temperature regime. Therefore, here the electric fan turns on at a higher temperature than the classic. The sensor contacts (2108–3828010) close at 99 °, open at 94 °.

The sensors of the new generation do not need the help of a power relay - they are able to switch the current up to 20 A. themselves. The temperatures of their operation remain the same, and the indices are 661.3710 (for classic, catalog number 2110-3828010-10) and 66.3710 (for "Samar" and “Ten” with engines 21083, number 2110–3828010). At the same time, on all models of “ten”, “Samar” and “Lada”, it is also envisaged to use a new fuse box - a European type.

You can distinguish them by the numbers stamped on the faces of the turnkey hexagon. On the sensors of the new generation, the first numbers of the marking are stamped: “661” (for the classics) or “66” (for “Samar” and “ten”), on the old ones - TM-108. In any case, the trip temperature must be indicated on an adjacent plane.

New sensors can be safely replaced instead of old ones. On the contrary - in no case! Contacts "one hundred and eighth" simply burn out, unable to withstand a large current. In a hypothetical situation - the sensor failed, and there is only TM-108 at hand - you will have to change the power supply circuit of the electric fan by introducing a power relay into it.

As for injection engines (VAZ 2111 and VAZ 2112), their electric fan for the cooling system is controlled by a controller (“injection brains”). The latter measures the temperature of the coolant with one of its special sensors. Therefore, in the radiators of the cooling systems of these machines there is no sensor for switching on the electric fan.

P. S. When the number was made up, we were informed that changes were made to the design of the thermostat 2112. In the inlet pipe, there will now be not one throttle hole in the center, but four located in a cross closer to the walls. In this case, when the valve is open, the liquid washes the thermopower element more reliably.

Thermostats of VAZ cars: 2101 - on the left, 2108 - in the center, 2110 - on the right.

A plastic shutter is visible in the bypass (optional) valve area.

Thermostat 2112. This is how the throttle hole of the "small circle" looks.