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Replacing the thermostat on the "Prior": instructions for the driver

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Replacing the thermostat on the "Prior": instructions for the driver
Replacing the thermostat on the "Prior": instructions for the driver

“Lada-Priora” is one of the cars of the “VAZ” family. And as a typical representative, he is not without some shortcomings that arise at the most inopportune moment. Insufficient heating of the engine in winter or overheating in the heat of summer while stuck in a traffic jam can all be caused by a malfunction of the cooling system.

Replacing the thermostat on the Priore is a simple task for any motorist.

The purpose of the thermostat

This little detail makes a huge difference. It is the thermostat that allows the engine to operate at the optimum temperature. As part of the cooling system, it acts as a valve that does not allow the coolant to circulate in a large circle (through the radiator) until it reaches operating temperature.

thermostat operation diagram
thermostat operation diagram

The cooling system has 2 circuits that are interconnected through a thermostat. Small circle allows in cold weather bothwarm up the engine faster. Until the coolant temperature rises to 70-75 degrees, the thermostat is completely closed. It begins to open slightly in this thermal gap and is fully open when it reaches 95 degrees.

As the valve opens, hot coolant is mixed into a large circle, where it, passing through the radiator, gives off part of the heat to the atmosphere. In case of violation of the operating mode, the Priora thermostat should be replaced.

Causes of failure

The operation of the thermostat largely depends on how well it is assembled. If a quality part is installed on the car, and the owner uses good antifreeze and changes it in a timely manner, then the thermostat can last the entire life of the car.

Unfortunately, the coolant does not always comply with GOST, and the parts supplied to the conveyor undergo quality control. All this leads to the fact that the replacement of the thermostat on the "Prior" becomes inevitable.

broken thermostat
broken thermostat

The main reasons for failure are as follows:

  1. Depressurization of a brass flask in which wax is sealed. During operation, brass solder corrodes, as a result of which its integrity is violated. This malfunction manifests itself in the fact that the valve opens completely, but is not able to close back. The antifreeze constantly passes in a large circle, and the engine cannot warm up to operating temperature.
  2. Ingress of foreign particles into the thermostat. This happens if the coolant has not changed for a long time, and also diluted with water, andscale. In this case, the valve can jam in both the open and closed positions. In the first case, the warm-up will take longer than usual, and in the second, the internal combustion engine will overheat.

Diagnostic Methods

When the thermostat works properly, the car engine heats up to operating temperature in 5-10 minutes at an ambient temperature of at least 0 degrees. If the warm-up takes longer, then making sure that the thermostat is the culprit is quite simple. For this you need:

  1. Start the engine and wait until the coolant temperature on the instrument panel is around 85 degrees.
  2. Open the hood and find the pipe going from the thermostat to the radiator. It should have approximately the same temperature with the rest of the pipes of the cooling system. If it is much colder, then the valve is either closed or not fully open. This is a good reason to replace the Lada Priora thermostat.

Signs of problems

Even if you do not carry out diagnostics, you can suspect the presence of thermostat malfunctions during the operation of the car. They will manifest themselves as follows:

  1. The engine takes a long time to warm up.
  2. Heating the coolant to a temperature of 130 degrees and above.
  3. Sensor shows the temperature when stopped is much higher than when driving at speed.
  4. The lower thermostat hose starts to warm up immediately after starting the engine. This indicates that the valve is not fully closing.
  5. The lower pipe is cold at the same timethe time when the temperature on the instrument panel approaches one hundred.

The last item reports a closed valve, except when the cooling fan is faulty, which does not require the replacement of the Priora thermostat.

new model thermostat
new model thermostat

DIY replacement

Before doing work, you need to understand if there are any differences in replacing the thermostat on the Priore with 16 valves from the same model with 8 cells. Despite the difference in power, the differences in the engines are not significant. Both are made on the basis of the same cylinder block. Only the cylinder head and the gas distribution mechanism differ, and the node itself, in which the division into small and large circles takes place, is the same. This means that replacing the thermostat on the Priora 16 cl is no different, except that it needs to remove a decorative plastic cover that covers the engine.

dismantling the thermostat
dismantling the thermostat

To change the thermostat you need:

  1. Drain the antifreeze from the radiator. To do this, unscrew the tap at the bottom, and also remove the plug from the expansion tank. The drain container must be prepared at least 5 liters.
  2. Unscrew the clamp of the pipe going to the radiator and pull it off. A little more coolant will flow out, so you need to substitute a drain bottle.
  3. In the same way, remove the opposite pipe.
  4. Remove the 3 thermostat screws with a hex wrench.
  5. Move from the old thermostat to the new O-ring, lubricate the surfaces adjacent to each other with silicone sealant.
  6. Reinstall the new thermostat and tighten the bolts.
  7. Install the pipes in place, after lubricating the seats on the thermostat with silicone sealant.

Extra Tips

Before replacing the Priors thermostat, it makes sense to check the new one for operability. To do this, the part is placed in a pot of water.

thermostat check
thermostat check

Gradually heating the water, you need to monitor how the valve opens. If it is fully open at a temperature close to boiling, then it can be installed on the machine.

After replacement, do not forget to add antifreeze to the cooling system to the operating level indicated on the expansion tank. If a certain amount of coolant was spilled during draining, then you need to add the same color as the main liquid. Antifreezes of different colors do not match.

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