What Cause High Water Temperature in Diesel Generator Set?

Diesel generator sets play an important role in engineering machinery, providing stable power support for various equipment. However, during operation, excessively high water temperature is a common and troublesome problem. If not resolved in time, it will not only affect the performance of the generator set, but may also cause equipment damage, increasing maintenance costs and downtime. This article will deeply explore the causes of high water temperature in diesel generator sets and provide some effective solutions to help you ensure the normal operation of the generator set.

The cooling system is a key part of the generator set. It is responsible for dissipating the heat generated by the engine and keeping the engine operating within the normal temperature range. If the cooling system has problems, it will lead to high water temperature. The following are some common cooling system problems and their solutions.

Coolant is the core of the generator set's cooling system. It carries away the heat generated by the engine through circulation, keeping the engine within the normal temperature range. If the coolant is insufficient or not replenished in time, cooling performance will decrease, causing the coolant temperature to rise. In addition, using poor-quality coolant, such as not adding antifreeze, will reduce the boiling point of the coolant, increase the formation of scale, and affect heat dissipation. Therefore, regularly checking the coolant level and quality, and promptly refilling or replacing suitable coolant, is very important.

If there is air in the cooling system that is not discharged, bubbles will form, hindering the normal circulation of the coolant. These bubbles reduce the contact area between the coolant and the engine, lowering heat dissipation efficiency and causing water temperature to rise. After adding coolant or repairing the cooling system, be sure to ensure that the air in the system is completely discharged. This can be done by opening the exhaust valve in the cooling system, or by observing the coolant circulation during engine operation to ensure no bubbles are generated.

The radiator is a key component of the cooling system, responsible for dissipating the heat in the coolant into the air. If the radiator fins are largely collapsed, or if oil sludge and debris block the gaps between fins, it will prevent heat from dissipating, causing the water temperature to rise. Especially when oil adheres to the radiator surface, the sludge mixture formed by dust and oil has a lower thermal conductivity than scale, which will seriously hinder heat dissipation. The solution is to carefully reposition the radiator fins back to their original state with a thin steel sheet, restore the flat shape of the fins, and then clean the radiator with compressed air or a water gun. If the water is heated and sprayed after adding cleaning solution, the effect will be better.

The water temperature sensor is an important component for monitoring engine water temperature. It transmits the water temperature signal to the control unit so that the cooling fan can be adjusted in time. If the water temperature sensor is damaged, or the wiring is shorted, or the gauge malfunctions, it will cause false alarms, making it impossible for the operator to accurately understand the actual engine water temperature. At this time, a surface thermometer can be used to measure the temperature at the sensor location and compare it with the gauge reading to determine whether the sensor and wiring are working properly.

The fan is an important part of the cooling system. It generates airflow through rotation to help the radiator dissipate heat. If the fan speed is too low, or the blades are deformed or installed in reverse, the air supply will weaken, causing coolant temperature to rise. In addition, if the fan belt is too loose, slippage will occur, also leading to low fan speed. If the belt is found too loose, it should be adjusted immediately; if the rubber layer is aged, damaged, or the fiber layer is broken, the belt should be replaced with a new one. To check whether the fan is operating normally, turn on the cooling system. If the compressor has already started but the fan does not rotate, then the fan must have failed. When the water temperature sensor is disconnected, the fan will run automatically to protect the engine, so this can be judged by unplugging the sensor.

The water pump is responsible for circulating the coolant in the cooling system. If the pump is damaged, the speed is too low, or too much scale has accumulated inside the pump narrowing the passage, the coolant flow will decrease, heat dissipation performance will be reduced, and generator oil temperature will rise.

The thermostat controls the large and small cycles of the cooling system. A properly working thermostat begins to open at about 85°C, and fully opens at about 105°C. To check the thermostat, remove it and suspend it in a container of warm water, placing a thermometer in the water. Then heat from the bottom of the container, and observe the water temperature at which the thermostat valve begins to open and fully opens. If it does not meet the above requirements or is obviously damaged, the thermostat should be replaced immediately.

The internal condition of the engine directly affects the efficiency and stability of the generator set. If the engine has internal problems, it will not only cause high water temperature but may also trigger other faults. The following are some common internal engine problems and their solutions.

The cylinder gasket is an important sealing part of the engine. If it is burned by high-temperature gases, high-pressure gases will rush into the cooling system, making the coolant boil. To determine whether the gasket is burned, turn off the generator set, wait a moment, then restart it and increase speed. If large bubbles emerge from the radiator filler cap and water droplets are expelled with the exhaust, the cylinder gasket is damaged.

The injector is a key component of the engine fuel system. It sprays fuel into the combustion chamber in mist form. If the injector operates poorly, such as the fuel supply advance angle being too early or too late, high-temperature gases will have a larger contact area and longer contact time with the cylinder wall, increasing heat transfer to the coolant and raising its temperature. At this time, the generator set usually shows reduced power and increased fuel consumption. If the injector pressure decreases and atomization is poor, fuel cannot fully burn, exhaust temperature increases, and water temperature rises indirectly. When the generator set is overloaded, the fuel supply may be excessive. If the heat generated exceeds the cooling capacity, coolant temperature will also rise. In this case, the generator set is often accompanied by black smoke, increased fuel consumption, and abnormal sounds.

If fuel injection timing is too early or too late, it will affect the combustion process, prolonging afterburning and increasing the contact time between coolant and cylinder walls, causing high water temperature. This usually depends on the brand of the diesel engine, as injection timing differs between brands. Unless the machine is damaged, ordinary engines generally do not have this problem.

If fuel injection pressure is too high or too low, it will affect the stroke and atomization quality. If the pressure is too high, diesel sprayed on the chamber wall will remain liquid, hindering atomization and even causing poor combustion. If the pressure is too low with poor atomization, injector drips will increase fuel supply, causing high water temperature. In severe cases, the injector may even burn out.

Incorrect valve timing will reduce cylinder compression pressure at the end of compression, causing insufficient intake and incomplete exhaust, prolonging afterburning and causing water temperature to rise. Blocked intake systems can also make the mixture too rich, causing black smoke, reduced power, and high water temperature. In addition, valve and valve seat wear, and piston and cylinder liner wear, will reduce compression, cause poor combustion, and result in high water temperature and decreased power performance.

In addition to the above-mentioned cooling system, sensors, fan, water pump, thermostat, and engine internal problems, there are also other factors that may cause high water temperature in diesel generator sets that need attention.

Radiator blockage is one of the common causes of high water temperature. Once blocked, coolant cannot circulate normally, and cooling fails. The main sign is that the radiator and return pipe remain at normal temperature (when they should be hot), and because of gas expansion inside the water pipes, both upper and lower pipes become very hard. This situation often occurs in summer. During inspection, just open the hood and check if too much debris is caught in the radiator behind the bumper. If the blockage is too severe, the radiator needs to be cleaned at a repair shop.

The water pump belt may slip or idle after long use. The main feature is that after pressing the accelerator for a while, it returns to normal. If slipping or idling occurs, the belt should be adjusted or replaced in time to ensure normal pump operation.

High water temperature in diesel generator sets is a complex problem that may be caused by many reasons. From the above analysis, we can see that the cooling system, sensors and circuits, fan and belt, water pump and thermostat, internal engine parts, and lubrication and exhaust conditions can all affect generator water temperature. Therefore, in daily use, we need to regularly inspect and maintain each component of the generator set, promptly detect and solve problems, and ensure that the generator operates within the normal temperature range. Only in this way can the service life of the generator set be extended, efficiency improved, and reliable power supply provided for the stable operation of engineering machinery.

In short, excessively high water temperature in diesel generator sets is a problem that cannot be ignored. We must pay great attention and take effective measures to solve it. Through reasonable maintenance and management, we can effectively avoid various problems caused by high water temperature and ensure the safe and stable operation of the generator set.