Which thermostat to install on UAZ Patriot

The power unit in the Russian SUV UAZ Patriot is the ZMZ-409 engine. Like any other engine, it requires the presence of a cooling system, and it must function properly and continuously while the engine is running. If this condition is not met, the engine will experience overheating and subsequent failure.

In order to eliminate such negative consequences, the UAZ Patriot system requires continuous temperature control. If the temperature level displayed by a special sensor exceeds 90 degrees, then the driver should immediately stop the engine and find out the reasons for the violation of the regulatory regime. It will probably need replacement.

In the cooling circuit of the UAZ Patriot engine, a very important component is the thermostat for the 409 engine. It is this detail that our material today is devoted to. Here we will look at what the purpose of the thermostat on a 409 engine is and how to replace it if it begins to show signs of malfunction.

The purpose of the thermostat in this car

The device is designed to redistribute flows during coolant circulation between the so-called small and large circles. In the first case, the thermostat on the 409 engine closes the circuit in a small circle when the liquid circulates in the cooling jacket and radiator of the UAZ Patriot heating system. This situation occurs when the engine warms up to operating temperature. When a certain temperature limit is reached, the valve inside the thermostat begins to move, thereby opening the path of liquid in a large circle. In this case, the coolant circulates through the main radiator, which, with the help of a fan, removes excess heat. If faulty, replacement is required.

Features of the thermostat in UAZ Patriot

With operating experience, UAZ Patriot owners noticed that the standard thermostat for the 409 engine has a short service life. The main reason for incorrect operation is that the valve inside the thermostat begins to open earlier than the temperature level corresponding to the operating mode of the UAZ Patriot engine is reached. If the factory calculates that the thermostat should open when the temperature reaches 87 degrees, which is actually the operating mode, then the valve often begins to open already at 76-78 degrees. What does this situation lead to? Firstly, warming up the engine takes significantly longer, and secondly, in cold weather it becomes problematic to fill the cabin with hot air.

The thermostat on the 409 engine that has shown to be faulty must be unconditionally replaced. Here the owner is advised not to bother changing the unit to a standard analogue, because the risk of changing an awl for soap is very high. You can act more rationally and install a higher quality product, for example, “TAMA” from Pajero.

Another well-known option is “Pekar”, but its operating temperature is 80 degrees, but in reality it barely reaches 75 degrees. A characteristic feature of “TAMA” is the fact that during operation the refrigerant temperature rises by 1 degree. That is, the operating temperature level here is 88 degrees, and when the standard product is functioning - 87 o.

For the ZMZ-409 motor, TAMA is installed without any need for modification, since the geometric parameters of both parts are identical. But this is true for trim levels equipped with Euro 3 or Euro 4 systems.

What if the UAZ Patriot is equipped with Euro 2? In this case, installation is also possible, but with the condition that the thermostat plate is replaced with an analogue from a standard product. This is necessary for the valve to completely close the channel to the pump. It is also possible to “adjust” the existing plate from TAMA to identical dimensions with the standard device.

By performing such a replacement, the owner of the UAZ Patriot will provide a significantly longer thermostat resource, and the engine will begin to warm up with noticeable efficiency.

Now let's move on to considering situations in which the thermostat requires replacement. Let’s also figure out how to identify the presence of a malfunction?

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What is a thermostat for?

On any engine, the thermostat performs the same task. It consists in regulating the temperature of the coolant. Due to the circulation of antifreeze in the cooling system, warming up of the engine when starting it is accelerated and the required temperature is maintained.

When the unit starts, the thermostat blocks the flow of antifreeze until the engine warms up to the desired temperature level. When the unit is cold, liquid does not pass through it, which means the unit heats up much faster. This process takes literally a couple of minutes. Coolant begins to enter the system of the unit only when it warms up to 87 degrees, this is the case with UAZ Patriot cars.

Then the thermostat opens and antifreeze begins to flow into the engine. Such a cooling system device has two advantages:

reduction of engine wear;
reducing the amount of harmful exhaust gases.

Despite the fact that only high-quality materials with an increased service life are used in the manufacture of thermostat parts, the mechanism operates under extremely aggressive conditions, so sometimes it can fail. The risk increases at high air temperatures during the warm season.

Disadvantages of the mechanism

Important! The Ulyanovsk thermostat for the Patriot class Euro-3 and Euro-4 has an extremely short service life due to the technical features of its design.

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The problem of a breakdown of the cooling system is quite typical for the UAZ Patriot jeep. A factory part fails at the most inopportune time. The Potomac leads to the following consequences:

The thermostat should open when the temperature reaches 87 degrees. If it is faulty, its operating temperature drops to about 70 degrees, as a result the unit begins to operate at the wrong temperature, its service life is reduced, and the stove stops supplying fairly warm air into the cabin for proper heating.
The engine will overheat too quickly, which can lead to serious damage.

The consequences of a thermostat malfunction will depend on the nature of its failure. We will try to understand further the nuances of the failure of this important mechanism.

Thermostat malfunctions in Patriot

Among the main signs is a disrupted operating temperature. This can be observed from the temperature sensor, when its needle for a long time cannot approach the operating threshold (87 degrees), but stops at a significantly lower reading.

Sometimes the valve gets stuck in the closed position. Here everything will happen the other way around, that is, the temperature will continue to rise far beyond the operating limit (87 degrees). There is a risk of motor overheating. In addition to the thermostat, in such a situation the driver can be “let down” by the fan, which may refuse to start at the required moment. You should also check the refrigerant level in the tank. If the fan is working and the level is normal, then you can now safely “blame” the thermostat on the 409 engine.

How to check if the thermostat is working correctly? The product will need to be dismantled (discussed below). Place the removed part in a container with water. Heat to a boil and watch the valve. If it refuses to move, then we determine the output and build the thermostat.

So, the product is considered operational if:

the valve opening temperature is 78 degrees;
temperature when fully opened is 87 degrees.

Purpose of the product

The thermostat in the ZMZ-409 cooling system is designed to distribute the flow of engine coolant. Thanks to it, the liquid is distributed into two circuits. The first circuit has a small circle, and the liquid circulates in the cooling jacket and the interior heater radiator. The second circuit also includes the circulation of liquid through a large radiator.

Thus, we can say that a thermos is a kind of regulator that opens a large circle of circulation of coolant after it has been heated. If it were not there, then when the engine was started, fluid would immediately circulate in both circles, which would lead to a very long warm-up of the ZMZ-409 engine.

Peculiarities

The standard Ulyanovsk-made thermostat on the UAZ Patriot SUV Euro-3 and Euro-4 has an extremely short service life. To be more precise, its malfunction lies in the fact that the temperature of the coolant decreases. That is, it was established from the factory that it should operate when the engine temperature reaches 87 degrees and only after that it should turn on and function in this mode. Thanks to the temperature of 87 degrees. (operating temperature of the ZMZ-409 internal combustion engine) ensures normal operation of not only the internal combustion engine, but also the interior heater. When the standard one malfunctions (a very common problem on Patriots), the temperature drops to 76-77 degrees. As a result, the engine operates at the wrong temperature and in the cabin you have to turn the heater control to maximum in order to achieve some warmth in the cabin.

When the thermostat is faulty, it cannot be repaired and must be replaced with a new one. But you shouldn’t rush to change the awl for soap, because you can install a higher quality product, like those from Pazhdero. “Pekar” is also known, but its operating temperature is 80 degrees, and in fact it does not rise above 75.

The Tama thermostat is characterized by the following features: it raises the antifreeze temperature one degree higher than standard mechanisms. That is, “Tama” has an operating temperature of 88 degrees, while the standard temperature is 87. On the UAZ Patriot ZMZ-409 SUV with environmental standards Euro-3 and Euro-4, the “Tama” thermostat is installed without changes, since it is sized they are similar.

If you are the owner of an SUV with Euro-2 or lower, then you can install a Tama thermostat, but you will need to replace the plate with the one installed on the standard one. That is, replacement is needed so that “Tama” can block the inlet hole on the pump. In order to install a Tama thermos on a UAZ Patriot SUV Euro-2 and below, you need to adjust it to the standard size.

After replacement, the service life of this unit will be much longer than the standard one, and in addition, the interior will become several degrees warmer with the same position of the heater control. Therefore, if you are wondering which thermos is best for your Patriot, then there is only one solution - “Tama” from Pajero.

So, we looked at what the thermostat on a UAZ Patriot with a ZMZ-409 engine is, and what the operating temperature is. Let's consider when a product needs to be replaced or how to determine its malfunction?

Malfunctions

The first sign of a thermos malfunction is a violation of the temperature regime. That is, if you notice that the operating temperature of the engine is not 87 degrees, but lower, then you should think about replacing the thermos soon. It can also jam, causing the engine to reach temperatures above 87 degrees. In this case, you need to lift the hood and make sure that the cooling fan is working properly and that there is antifreeze in the expansion tank. If the fan is working properly and the antifreeze is normal, then most likely the plate is jammed, as a result of which the liquid does not flow in a large circle and does not cool.

In this case, it is necessary to remove the thermos (we will look at the process below) and check its serviceability. To do this, the product is placed in a container of water, after which the water must be heated. If the water is brought to a boil, and the valve does not react in any way, then it is faulty and requires replacement.

The product is considered working when:

the valve opening temperature is 78 degrees;
its full opening temperature is 87 degrees.

Replacement

If the operating temperature of the thermos is violated, the product should be replaced. Replacing the thermostat on a UAZ Patriot SUV is carried out in the following sequence:

First, you need to drain the antifreeze.
The fastenings of the power steering pump are unscrewed. The pump is diverted to the side.
The clamp is loosened and the radiator hose is disconnected from the housing where the thermostat is installed.
There are wires on its body that need to be disconnected.
Next, you will need to loosen the upper clamp on the connecting hose of the thermostat and pump.
The screws securing the housing in which it is installed are unscrewed.
Before removing the body, you should loosen the lid and then remove the thermos body.
Now you can unscrew the bolts securing the thermos body cover and clean the old gasket.
After this, the thermostat is removed and replaced with a new one.

The manufacturer recommends installing a similar device, otherwise it is not responsible for the consequences. But this article makes it possible to conclude that it is better to replace the standard thermos with a foreign analogue. Installation of a new product is carried out in the reverse order of removal. After installation, fill in the liquid and check what the operating temperature of the device is now, which should be 87-88 degrees, depending on the installed thermos model.

To summarize, it should be noted that the serviceability of the thermostat on the UAZ Patriot SUV and other cars is very important, since its failure leads to the impossibility of further movement. Good luck with your choice and replacement at home.

Replacing the thermostat in a UAZ Patriot

The replacement is performed on a cooled motor and has the following sequence of manipulations.

Drain the refrigerant. We attract a suitable container.
Unscrew the fasteners of the hydraulic steering pump. We move the pump unit to the side.
On the supply hose from the radiator to the UAZ Patriot thermostat housing, loosen the clamp and move it.
Disconnect the connectors with wires from the plugs on the case. Replacement continues.
We also loosen and move the upper clamp present on the hose from the body to the pump, after which we tighten the pipe itself.
We unscrew the screws securing the housing, having first loosened the fastening of the cover.
Remove the housing, and then completely unscrew and remove the cover.
We take out the thermostat.

Before installing the product, install a new gasket. Replacement is complete.

Self-replacement of the thermostat on a UAZ Patriot (ZMZ 409).

Hello, dear readers. The topic of today's article is replacing the thermostat on a UAZ Patriot (ZMZ 409). Traditionally for our site, the article contains photos and video materials.

The thermostat is the second most important structural element in the cooling system after the pump, and if it malfunctions, the following options are possible:

The engine takes a long time to warm up, and in winter it does not heat up above a certain temperature at all. This indicates that the thermostat is stuck open or has changed its characteristics and needs to be replaced.
The engine is boiling and throwing antifreeze out of the expansion tank, but at the same time the lower radiator pipe is cold and the upper one is hot - this indicates that the thermostat is stuck in the open position and also needs to be replaced, and in general we have a separate, detailed article on our website about typical cooling system malfunctions.

Tools needed to replace the thermostat:

Screwdriver
hexagon "6"
open-end wrench "12".

The sequence of actions required to replace the thermostat:

We drain all the coolant from the UAZ Patriot engine cooling system.
We unscrew the fastenings of the power steering pump and move the pump itself to the side.
Carefully loosen the clamps securing the pipes.
We disconnect all the wires from the sensors on the thermostat body, having first written down how they are connected (or photographed). If the car is more than 5 years old, it is necessary to remove the wires with the utmost care, as they become fragile.
Remove the pipe from the thermostat housing cover and move it to the side.
Loosen the hose clamps that connect the thermostat housing and the pump.
Next, unscrew the fastening bolts that are responsible for fixing the thermostat housing. It is important to remember that before removing the housing, it is advisable to loosen the cover fastenings.
Now we can easily remove the body.
Next, using an open-end wrench, we finally unscrew the bolts securing the thermostat cover.
Remove the cover and remove the thermostat. After removing the old thermostat, it is important to pay attention to the temperature marking of the thermostat so that, if necessary, you can purchase exactly the same one.

We are replacing the thermostat with a new one! Which it is advisable to “weld” first to ensure its serviceability.

How to weld a thermostat?

We lower the thermostat into the water and gradually heat it up. It is important not to miss the temperature moment of valve opening. If the thermostat is working properly, the valve will begin to open at a temperature of 72-78 degrees. It is worth noting that the valve must open completely before reaching 82-96 degrees (depending on the characteristics). If the characteristics of the thermostat differ from those stated, exchange it with the seller; according to our statistics, only one thermostat out of three is fully operational.

How can I make it easier to replace a thermostat in the future?

Much can be forgiven to the developers of the ZMZ 406-409 engine family, but how, after 20 years of mass production, have they still not changed the thermostat housing to conveniently replace the latter? On older engines, changing the thermostat took 10 minutes, and this required removing one clamp and unscrewing 3 bolts. I have had to spend one and a half to two hours of time on ZMZ 406 and its descendants for 20 years now.

In the future, this “ratsuha” will help simplify the replacement of the thermostat:

You can read more about it in this article.

That's all for me today! I hope that the article fully answered the question of how to replace the thermostat on a UAZ Patriot. If you have any questions or want to share your experience, write comments.

Best regards, administrator

Let's sum it up

As it turns out, the thermostat on a 409 engine is a very important component in the cooling circuit. On the ZMZ-409 UAZ Patriot engine, replacing it turned out to be a simple procedure. The manufacturer recommends replacing a worn-out element with a new factory-made analogue, however, as we understand, this product is not famous for its service life and correct operation. Here it is better to lean towards choosing a higher quality analogue, which we mentioned in this article. After assembling the circuit and starting the engine, we check the system for refrigerant leaks.