Early car engines did not have that essential accessory we consider necessary today: a pump. The liquid cooling medium used was pure water, mixed with little more than phenyl alcohol, to prevent freezing. The circulation of cooling water depends entirely on the natural phenomenon of thermal convection. After the cooling water absorbs heat from the cylinder body, it naturally flows to the channel  and enters the radiator’s edge; As the cooling water cools, it naturally sinks to the bottom of the radiator and into the lower part of the cylinder block. Using this thermosiphon principle, cooling can be barely accomplished. But soon after,  water pumps were added to the cooling system to allow cooling water to flow more quickly.

The cooling system of modern automobile engine  generally adopts centrifugal water pump. The most reasonable installation location of the pump is at the bottom of the cooling system, but the  part of the pump is installed in the middle of the cooling system, and a large number of pumps are installed at the top of the engine. The pump installed at the top of the engine is prone to cavitation. No matter in what position, the pump pump water is , such as Naitai V8 engine pump pump water, idle speed is about 750L /h, to the full speed of about 12000L/h.

From the service life point of view, the most important change in the pump design  is that the ceramic seals appeared a few years ago. Compared with the rubber seals or leather seals used before, the ceramic seals are more wear-resistant, but it also has the disadvantage of being easily scraped by the hard particles in the cooling water. Although in order to prevent the pump seal failure in the design of  to carry out continuous improvement, but so far can not guarantee that the pump seal is not a problem.  Once the seal appears leakage, then the lubrication of the pump bearing will be washed away.

1. Fault diagnosis

In the past 20 years, the durability of cars has been improved by , so is the service life of water pumps getting worse than ever? Not necessarily. Today’s pumps still need to be replaced  amount of work, the car drove about 100 thousand kilometers, the pump at any time there is a possibility of failure.

The pump fault diagnosis  generally speaking is relatively simple. In the case of leakage of the cooling system, the smell of thermal antifreeze can be smelled, but it is necessary to check  to find out whether the cooling water is leaking from the pump shaft seal. Can use  surface small mirror light to check whether the water pump vent hole is leaking. To regular  maintenance, pay attention to check the loss of water tank coolant.

Leakage is the number one fault of the pump, noise is the second fault, because of bearing abrasion and cause the phenomenon of the pump shaft bite dead, is very  see.  Once this phenomenon occurs, the radiator will be damaged after the wind.

Although serious corrosion of water pump impeller is often seen in the literature of automobile maintenance, but if normal maintenance is done, impeller corrosion is not a common phenomenon . When you see the coolant red, rust color, it is estimated that the problem of  impeller corrosion. At this time, you need to check the circulation of the pump coolant, the coolant in the radiator can be released  part, so that the water level is just kept in the water pipe, and then preheat the engine, the temperature device is in a fully open position. Good water circulation should be seen when the engine is running at 3000r/min. Another  possible problem is that the pump impeller appears in the shaft.

2. Cause of failure

As for the cause of the pump failure, some authorities believe that with  belt drive accessories more and more, so that the side load of the cause. As  seal experts said, “there is evidence that the resonance of the attachments with the root belt drive has a different frequency, which can destroy the seal of the pump.” Another  problem with pump failure is that the tensioning device of the serpentine belt exerts a critical lateral load on the pump. Cavitation is another  problem of the pump, as in the water side of the pump corrosion, so usually installed with a pressure radiator cover. When replacing the pump, it is recommended that  new fan clutches be installed, as an unbalanced clutch may cause problems with the pump.

There are experts that overheating  lack of maintenance is also the cause of the pump problems. If the coolant loses its ability to lubricate the seal , the seal may be chafed. In addition, the pump failure may also be due to the poor quality of the pump itself.

3. The science of belts

The old model  generally adopts the ordinary V-shaped belt, while the new model may adopt the serpentine belt. If the old model of the pump installed in the new model , there may be a direction of the problem. Because the serpentine belt may drive the pump impeller in the opposite direction to the V-belt, the pump will rotate in the opposite direction, resulting in overheating of the coolant.

Now more and more engines use the timing belt of the nap-camshaft to drive the water pump. The advantage of doing this is that if the water pump does not rotate, the car can not be driven, and can shorten the engine  degree. It must be emphasized that the timing belt should be replaced after an appropriate period of  time. Sometimes you see this  kind of situation. In the installation of  new timing belt within a short time, the water pump was damaged, generally this is due to increase the tension of the belt. Therefore, when installing  new pumps, do not lightly switch to a new belt.

4. Maintenance of water pump

Here to talk about the problem of coolant, and maintenance  some matters needing attention. In modern cars , which often use an all-aluminum engine with a higher thermal load, changing the coolant every year seems to be the best way to prevent problems. However, now the antifreeze formula is very advanced, so that the coolant replacement interval is continuously extended . At first, the coolant replacement cycle was recommended for three years, then extended  to four years, and now GM is recommending five years or 250,000 kilometers on some vehicles. The current coolant formula can avoid the problems that often appear in the cooling system due to the delay of  coolant replacement. The new coolant is resistant to the corrosion of carboxyl compounds, that is, the silicates, phosphates  waterways clogging inorganic substances found in common glycol. Although the new coolant is  more expensive than the traditional coolant, it can ensure that the pump is working properly for a long time, so it is cost-effective. In order to make the best use of  life coolant, the cooling system needs to be thoroughly cleaned when replacing.

Here to talk about the quality of antifreeze. The word “antifreeze” is a misnomer, because the use of antifreeze is not only for  antifreeze, but also requires corrosion resistance, lubrication pump seal to lift the boiling point. Therefore, unknown brand antifreeze should not be used as it may contain inappropriate additives  harmful pH values.

The seriousness of the cooling system leakage problem can not be estimated , which will not only make the inhaled air damage the predetermined coolant flow mode, leading to the generation of hot spots, but also aggravate the corrosion of the pump.

If the amount of coolant  period is insufficient, it will cause engine overheating, and with the appearance of steam corrosion, not only damage the radiator, but also produce other pump problems.