This is a Jinbei Hiace Power King 11-year-old car. The water temperature gauge now shows a high temperature and the electronic fan is operating normally.
(1) Too much scale in the water tank and engine water jacket
will cause poor heat dissipation and increase the water temperature. Clean waterways if necessary. To clean the water channel, remove the thermostat and flange, and check whether the thin water pipes on the cylinder head - the return pipe - the throttle body - the expansion tank are smooth. If they are not smooth, find a way to deal with them. The outside of the water tank is dirty or the air conditioner condenser and the water tank are blocked, etc., resulting in poor heat dissipation in the water tank and causing the water temperature to be high. Clean up when necessary. For cleaning, the radiator should be removed, spray the surface with external engine cleaning agent several times, rinse with clean water after a few minutes, and blow dry with a high-pressure air gun. The surface of the condenser is then cleaned with external cleaning agent.
(2) The thermostat is damaged and cannot be opened
The coolant cannot smoothly enter the water tank to form a large circulation, causing the water temperature to rise quickly and causing boiling. The thermostat determines whether to go on a "cold cycle" or a "normal cycle". The thermostat opens when the water temperature rises, and the higher the temperature, the wider the opening. The thermostat cannot be closed, which will cause the cycle to enter a "normal cycle" from the beginning, which will cause the engine to not reach the normal temperature as quickly or as quickly as possible. The thermostat cannot be opened or is not opened flexibly, which will prevent the coolant from circulating through the radiator, causing the temperature to be too high, or sometimes high and then normal. When overheating occurs because the thermostat cannot be opened, the temperature and pressure of the upper and lower water pipes of the radiator will be different. At operating temperature, if the thermostat main valve opening is insufficient or fails to open, the water in the cooling system cannot enter the radiator (to perform a large circulation). In order to ensure that the engine can reach normal operating temperature as soon as possible after starting, the engine uses a thermostat to automatically control the circulation of cooling water. When starting in the morning, the cooling water temperature is lower than the normal operating temperature. At this time, it is hoped that the water temperature will rise as soon as possible. Therefore, the main valve of the thermostat is closed and the auxiliary valve is opened so that the circulating cooling water does not have to flow through the radiator to dissipate heat and speed up the cooling water flow. The circulation route of heating and cooling water is: water pump → water jacket → water pump. When the temperature is higher than the normal operating temperature, it is hoped that the water temperature can drop to normal temperature at this time, so the auxiliary valve of the thermostat is closed and the main valve is opened to allow the circulating cooling water to flow through the radiator for heat dissipation. The circulation route of the cooling water is: water pump → water Set→radiator→water pump. Therefore, if the thermostat is damaged, the cooling water cannot flow through the radiator through the large circulation to dissipate heat, causing the engine cooling system water temperature to be too high.
(3) The water pump is damaged or the transmission belt slips, causing the water pump to be defective.
If the water pump cannot rotate normally to generate sufficient water pressure, it will also reduce the flow of cooling water. Because the circulating flow of cooling water applies water pressure through the water pump, the water pressure cooled by the radiator enters the engine water jacket, forcing the cooling water that has absorbed the heat to flow to the radiator to dissipate heat. If the water pump does not work well, it will cause If the water pressure is not high, the cooling water circulation flow rate will be reduced and the heat dissipation effect will not be obvious, causing the cooling system water temperature to be too high. The water pump is damaged and cannot send coolant to the water tank, causing poor coolant circulation and causing the water temperature to be too high until the pot is boiled. The water pump needs to be repaired or replaced with a new one. When replacing the timing belt, be sure to check the water pump for signs of leakage and replace it if leaking. Check one side of the timing belt carefully for signs of leakage. For vehicles with a mileage of more than 120,000 kilometers, it is recommended that car owners replace the water pump when replacing the timing belt. For vehicles with long mileage, the shaft and blades are easy to separate, so you must pay attention during maintenance.
(4) Lack of antifreeze
Too little coolant will also cause the water temperature to be too high, and the coolant must be added or replaced in time. Due to irregular addition and replacement of antifreeze, the engine water channel and water tank will be blocked in advance, resulting in high water temperature. Antifreeze should be replaced every two years, and original parts must be used when replacing and adding. If the concentration is too high, the heat dissipation effect will be poor and the engine will overheat. This hazard is not obvious when the engine is running at small to medium loads. When running at high speeds with large loads, the coolant temperature will be too high. Therefore, antifreeze stock solution cannot be added at will, and the concentration must be tested first. Different types of antifreeze cannot be mixed to avoid chemical reactions, formation of precipitates or bubbles, and reduced use effectiveness. When replacing antifreeze, start the engine first, then stop the engine and release the cleaning fluid.
Fill the cooling system with clean water. After idling for 10 minutes, drain the water. Repeat this several times until clean water flows out of the water channel, and then add new antifreeze and water.
(5) There is air inside the cooling system, causing the cooling water to not circulate normally.
(6) The cylinder gasket is damaged
As a result, the high-temperature and high-pressure gas in the cylinder enters the cooling system, causing the water temperature to quickly rise to boiling point. The cylinder gasket must be replaced with a new one. The cylinder gasket of the new two-valve is made of steel sheets. Generally, the cylinder gasket will not be burned by high water temperature for a short period of time, but it will be damaged when driving for a long time without cooling.
(7) There is leakage in components
If the engine water temperature is high, it must be checked to ensure that there is no leakage in the cooling system components. The leakage parts are multiple three-way water pipes at the rear of the cylinder head, water pumps, joints of each water pipe, radiator, thermostat, cylinder gasket, and reservoir pipe cover. In the case of leakage, be sure to use a detector to pressurize after completion and observe whether there is leakage in each component. In the cooling system, if there is water leakage in the radiator, water pump, cylinder block, cylinder head, cylinder gasket, heater water tank, water pipe, rubber hose and drain switch, the amount of water in the cylinder and cylinder head water jacket will be reduced. The circulating flow reduces the ability to absorb heat in the cylinder, causing the cooling water temperature to be too high.