What are the faults of car thermostats? What are the causes of car thermostat damage

In the engine cooling system of automobiles, there is a component that is related to whether the engine is working properly, and it is the automotive thermostat. The automobile thermostat automatically adjusts the amount of water entering the radiator according to the temperature of the cooling water, and changes the circulation range of the water to adjust the heat dissipation capacity of the cooling system and ensure that the engine works within the appropriate range. So what are the symptoms of a broken car thermostat?

Will the engine water temperature become very high when the thermostat is broken?

First of all, there are many factors that lead to high engine water temperature, including the failure of the car thermostat, which means that the failure of the thermostat may lead to an abnormal increase or decrease in the engine water temperature.

If the car thermostat is broken, then the most obvious symptom will be manifested in the water temperature gauge, the main valve of the thermostat is opened too late or too early, and if it is opened too late, it will cause the engine to overheat; If it is turned on too early, it will cause the engine to warm up for a longer period of time, and the temperature of the engine will be too low, which will affect the performance. To put it simply, if you see that the engine water temperature is too high or too low from the water temperature gauge, then it is possible that the thermostat is faulty.

How to judge the failure of the thermostat:

1. Check after the engine starts, open the filling port cover of the cooling water tank to see if the cooling water in the cooling water tank has water flow, if not, it means that the thermostat is damaged or there is a foreign object stuck between the main valve switches.

2. You can judge the temperature of the upper and lower water pipes by feeling the hands, first start the engine, touch the upper and lower water pipes after 3 minutes, if it is a good thermostat, the temperature of the upper and lower water pipes is not the same, and the upper and lower water pipes are generally hot and the lower water pipes are cold. When the engine water temperature reaches 90, the upper and lower water pipes are hot, which proves that the thermostat is good. If the temperature of the upper and lower water pipes is the same after starting the engine, the thermostat will be broken.

Hope! Thank you!

What are the analyses of car thermostat failures:

1. There are two fault phenomena of the thermostat: the first is that it cannot be opened when it is closed; The second is that it cannot be turned off.

2. Detailed discussion:

1) When the engine temperature is too high when it is turned off and cannot be opened, it will stall due to the high temperature. And because the thermostat is closed and the water tank system is cut off, the water with too high temperature and too high pressure cannot be pressed into the tank through the opening of the tank cover, so it may cause damage to the water jacket of the small circulation system, such as the pad, the heater tank, and some water pipes. But it will not cause damage to the large tank.

2) When the thermostat can only be turned on and not closed, the water temperature cannot be raised, especially in winter. The water temperature is low, the water temperature sensed by the water temperature sensor is also low, and the potential provided by the sensor to the computer is also low, and the instructions issued by the computer are actually wrong. The computer widens the pulse of the fuel injector, the amount of fuel injected increases, and the car consumes fuel.

First of all, the essence of the thermostat is a valve, which is used to control the size and circulation of the cooling system, and the general failure will lead to problems in the operation of the engine cooling system, which may lead to coolant leakage, engine overheating, slow engine heating and other phenomena.

Coolant leaks The thermostat is like a door that connects the small circulation channels on the engine block to the large circulation lines outside the engine. The installation location of the thermostat is the pipe connection of the two sets of circulation systems. The waterway has an interface here, so there is a risk of leakage.

Engine overheating There is no doubt that mechanical parts are immune to mechanical failure. The essence of a thermostat is a valve, and the most common mechanical failure is valve seizure.

The function of the thermostat: according to the temperature of the cooling water, the amount of water entering the radiator is automatically adjusted, and the circulation range of the water is changed to adjust the heat dissipation capacity of the cooling system to ensure that the engine works within the appropriate temperature range. The thermostat must be kept in good technical condition, otherwise it will seriously affect the normal operation of the engine.

If the main valve of the thermostat is opened too late, it will cause the engine to overheat; If the main valve is opened too early, the engine warm-up time will be prolonged, and the engine temperature will be too low.

To put it simply, when the thermostat is not opened, the antifreeze in the cooling system is a small circulation, and after the water temperature reaches a certain temperature, the small circulation can no longer cool the engine well, at this time the thermostat is opened, the antifreeze liquid in the cooling system goes to a large circulation, and the flow rate and flow of antifreeze are larger, which can effectively improve the cooling effect. Therefore, when the thermostat fails and is opened early, the flow rate and velocity of the antifreeze increase, so the water temperature rises slowly, and the water temperature will be too low.

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The common failure causes of thermostats are: the temperature of the valve opening and full opening is too high, or even cannot be opened, and the thermostat is not closed tightly. The former will cause the cooling water to not be effectively circulated, resulting in overheating of the engine, and in cold areas, the radiator will freeze because the cooling water is not circulated.

The latter will cause the engine to heat up slowly, causing the engine to subcool.

In addition, as the performance of the thermostat gradually deteriorates, the opening of the main valve gradually decreases, resulting in a decrease in the flow of cooling water entering the large circulation, and the cooling system will gradually overheat.

Most of the valves of the thermostat are made of aluminum alloy, which will corrode and rust due to the addition of unclean water for a long time. When the engine water temperature rises to 80, the main valve of the thermostat should be opened normally for large circulation.

If the valve is rusty and can't be opened, the cooling water can't enter the large circulation, it will produce a certain air pressure and pressure in the small circulation, but carry out counterflow, the small cycle can not withstand the increase of air pressure, and the reverse flow into the radiator, the reverse pressure directly attacks the radiator, when the radiator can not withstand such a large pressure, it will produce a corrugated heat dissipation band is squeezed together, commonly known as the phenomenon of "double eyelids", until the radiator expands and bursts.

If it is confirmed that the thermostat is working poorly after inspection, or its performance test does not meet the technical standards, it should generally be replaced with a new part.

1. Due to the prolongation of the warm-up time, the electric flat car runs under the condition of low water temperature, and the combustion gas and the condensed water of the cylinder wall form an acidic substance, which corrodes the cylinder;

2. The liquid fuel and water wash away the lubricating oil film of the cylinder wall, and flow down the oil pan along the cylinder wall, which dilutes the oil of the lubrication system, resulting in early wear of the cylinder liner, piston and ring.

3. If the cylinder is defective and repaired by glue, due to the lack of thermostat, the cold and hot changes of the machine temperature are too large, and the cylinder shrinks and expands frequently. It will make the glue repair or glue fall off, which will lead to the failure of the diesel engine.

The thermostat is an important part of the engine water temperature control, and the damage of this part will cause the engine water temperature to not be controlled in the range of 90-115. Exceeding this range increases the wear between the cylinder and the piston, as well as the cost of oil.

The main reason for the damage of the thermostat is that after a long time, it has been soaking in this antifreeze, and the spring may be stuck after a long time, or there is scale in it, which will cause the phenomenon of stagnation when the thermostat is working. There is also the aging of the medium in the thermostat after a long time.

Ask what is the reason why the thermostat is often broken, and answer that the thermostat is often broken, which is related to the quality of the thermostat, and the quality of the thermostat is not good. In addition, there are more impurities in this antifreeze and more scale, which will also cause damage to the thermostat.

Question Okay, thank you.

If the thermostat is stuck in one position, it either can't be opened or closed.

If the thermostat does not open, the water in the engine cannot circulate largely, and the water temperature remains high.

On the other hand, if the thermostat is always on and cannot be turned off, the engine is circulating at all times, and the water temperature rises very slowly and slowly.

A thermostat is a device that shuts off the large circulation of engine coolant. Under normal circumstances, when the engine temperature is low, the thermostat is turned off, and there is only a small cycle, so that the temperature rises quickly, and when the temperature rises to the temperature of the engine working normally, the thermostat will automatically open to make the coolant circulate to avoid the engine temperature being too high.

There are only two cases when the thermostat is damaged, one is that it cannot be opened, so that it can only run for a short time after starting the car, and the engine temperature cannot be too high. In this case, it must be better thermostat. The other is that it can't be turned off, so that as long as you are not afraid of the low water temperature, it does not have much effect.

However, it is still recommended to replace it.

The failure of the thermostat means that the thermostat cannot be opened, the height of the opening valve is not immediately or cannot be fully opened. The impact on the engine after the thermostat failure is objective, and some car owners do not necessarily replace it after the thermostat fails and is damaged, and it is also wrong to think that there is no impact on the engine. The following content is an analysis of the causes of thermostat damage, and I hope that car owners can pay attention to the use of thermostats.

Causes of thermostat damage.

The thermostat is installed at the water inlet of the radiator or the outlet of the cylinder head according to the principle of action. The internal structure of the thermostat is solid paraffin, like some quite good cars use electronic thermostats, and the internal valves are precisely adjusted by electronic components. The mechanically adjusted thermostat has the temperature at the beginning of the valve and the temperature when it is fully opened, and the electronic thermostat can realize the stepless adjustment of the valve according to the temperature level, so the valve will be opened a little bit every time the temperature is higher.

The following figure shows the internal structure of the thermostat, the thermostat includes double valves and single valves according to the number of valves, the top valve is called the main valve, if it is a double valve structure, the valves below are basically called auxiliary valves. The key to the thermostat's adjustment of the cooling system is to close the channel of the water outlet by opening and closing the main valve, when the water temperature of the engine is high, the main valve is opened, and the antifreeze in the engine water jacket flows to the water inlet of the radiator.

For example, we take the thermostat of Volkswagen's Jetta engine to carry out analysis, when the cooling temperature reaches 82 degrees, the main valve of the thermostat is opened and the valve of the side channel is gradually closed at the same time, until the water temperature of the engine reaches 95 degrees, the main valve of the thermostat is fully opened, and the valve of the side channel is completely closed, and the engine implements a large circulation at this time; When the temperature of the engine is lower than 82 degrees, the main valve is closed, the bypass valve is opened, and the engine implements a small cycle.

The fault problem forms of thermostat damage are as follows:

The thermostat won't open.

The energy saver can not be opened, the first task is the first reason for internal stagnation, from the thermostat structure diagram we can know that the key to the opening of the main valve of the thermostat is to rely on the internal push rod to push the main valve to make the main valve open, if the push rod is damaged the thermostat will not be opened.

The second reason is that the shell of the thermostat is broken, the paraffin material inside is leaking, or the thermostat is aging and the seal is poor. In these two cases, the only way to do this is to replace the thermostat, not to repair it.

First, the main valve of the thermostat has been closed for a long time, regardless of the water temperature, the coolant circulation line is pumped by the water pump, through the cylinder body water jacket, the cylinder head water jacket, the water outlet pipe, by the water pump to the cylinder body, that is, the so-called small circulation, which will inevitably cause the engine temperature to be too high, until the boil. At this time, the electronic fan rotates at high speed, the noise is loud, and the instrument may have a high water temperature alarm prompt.

Second, the thermostat is open for a long time, because there is no thermostat control, the cooling water circulation line has been through the cylinder block water pump and cylinder liner, water outlet pipe to the radiator, so that when the car starts, especially in winter, the engine starts when the cavity fails, the coolant water temperature rises slowly, so that the engine can not work at normal temperature, the engine temperature is lower than the required temperature, resulting in increased fuel consumption, increased engine noise, and excessive exhaust gas.

Whether the thermostat is working properly or not is directly related to the rotation of the engine. A thermostat failure is when the thermostat cannot be opened, the height of the valve is not high enough, or it cannot be fully opened. The impact on the engine after the thermostat failure is objective, but there are also car owners who do not necessarily have to replace the thermostat after the thermostat is damaged by the failure.

Causes of thermostat damage.

The thermostat is installed at the flow inlet of the radiator or the outlet of the cylinder head according to the principle of action. The internal structure of the thermostat is solid paraffin, and a fairly good car uses an electronic thermostat, and the internal valve is precisely adjusted by electronic components. Mechanically regulated thermostats have the temperature at which the valve is just open and the temperature when it is fully open, but the electronic thermostat can infinitely adjust the valve according to the temperature, so the higher the temperature, the valve will open slightly.

The diagram below represents the internal structure of a thermostat. Thermostats include double valves and single valves depending on the number of valves, but the top valve is called the main valve, and if it is a double valve structure, the lower valve is basically called the secondary valve. The key to the thermostat regulating cooling system is to open and close the main valve, close the outlet channel, and when the engine water temperature rises and the main valve opens, the antifreeze in the engine jacket flows to the water inlet of the radiator.

For example, the analysis is carried out with the thermostat of a general jet engine. When the cooling temperature reaches 82 degrees, the main valve of the thermostat is opened and the valve of the bypass channel is gradually closed. When the engine water temperature reaches 95 degrees, the main valve of the thermostat is fully opened, and the valve of the bypass channel is completely closed.

At this time, the engine performs a large cycle; If the engine temperature is below 82 degrees, the engine performs a small cycle when the main valve is closed and the bypass valve is open.

The malfunction problem form of thermostat damage is as follows:

The thermostat won't turn on.

The thermostat won't turn on, and the first task is that the first cause is internal blockage. As can be seen from the structural diagram of the thermostat, the opening key of the main valve of the thermostat is to press the main valve with the internal push rod to open the main valve. If this pusher is damaged, the thermostat won't open.

The second reason is a cracked thermostat housing, a leak of paraffin material inside, or an aging thermostat resulting in a poor seal. In both cases, only the thermostat is replaced, and it cannot be repaired.