What is the reason for the leakage of Cummins water tank cover?
Cummins NT855 diesel engine adopts wet cylinder liner, which directly contacts with the cooling water of diesel engine to dissipate heat. When cooling water washes the outer surface of cylinder liner during circulation, cavitation and cavitation will be formed on the outer surface of cylinder liner. Over time, dense pits will appear on the surface of the cylinder liner, and in severe cases, the cylinder liner will penetrate into the oil pan of the diesel engine. Check whether the cylinder liner is perforated or which cylinder liner is corroded, remove the oil pan of the diesel engine, fill the radiator tank with water, pry the diesel engine slowly, and observe whether there is water flowing out or dripping from the cylinder wall. If there is leakage of coolant, it can be judged that the cylinder liner is perforated. In addition, if the water stop ring of the cylinder liner is damaged, the coolant will also enter the oil pan. If the coolant is found dripping from the outer wall of the cylinder liner, it may be caused by the damage of the rubber water stop ring. When prying a diesel engine, if it is difficult to turn, you can't pry it forcibly; This situation may be caused by the coolant entering the cylinder during the compression stroke. If you don't pay attention at this time, you may damage the connecting rod or other parts of the diesel engine.
2. The oil radiator is damaged:
The heat dissipation of Cummins NT855 diesel engine oil depends on the cylinder oil radiator installed on the side of the diesel engine. The radiator core consists of a row of copper pipes, in which the cooling liquid flows and the diesel engine oil circulates outside; In the process of flowing, high-temperature engine oil is cooled by coolant to ensure a certain oil temperature. When the radiator copper tube breaks or the seals at both ends of the radiator core fail, the coolant may enter the diesel oil pan through the oil circuit. When the diesel engine is working, the pressure of engine oil should be higher than that of circulating water. Under the action of pressure difference, engine oil can enter the coolant through the gap of copper tube. At this point, the performance is that the diesel engine water tank has oil; When the diesel engine stops working, because the water level of the water tank is higher than that of the oil radiator, under the pressure caused by this height difference, the cooling water will enter the oil pan of the diesel engine through the radiator pipe and oil circuit, so it is necessary to judge whether there is oil in the diesel engine radiator. When the radiator core copper tube is damaged, it should be checked by compressed air. The specific method is as follows: seal both ends of radiator core with iron plate, and leave a small hole at one end. After the copper tube is filled with water through the small hole, 7 kilograms of compressed air is blown through the small hole and kept for 5- 10 minutes; If water or gas comes out from the radiator oil port, it can be judged that the radiator copper tube is damaged and needs to be replaced. In addition, if the seal between both ends of radiator core and radiator shell fails, cooling water may also enter the oil pan.
3. Cylinder gasket is damaged:
The cylinder head and cylinder block of Cummins diesel engine are sealed by cylinder gasket, and the cylinder water channel has corresponding sealing rings on the cylinder gasket to ensure that the coolant does not leak. The flatness error of the cylinder head or cylinder block plane of diesel engine exceeds the allowable range, which will inevitably lead to the lax sealing of the cylinder gasket and the possibility of coolant leaking into the oil pan. In addition, if the diesel engine cylinder head bolt is not tightened as required or the surface is not cleaned when cleaning, resulting in the cylinder gasket not being pressed tightly, the coolant will also leak at this time. It is difficult to accurately judge whether the cylinder gasket is damaged, and this inspection can only be carried out after troubleshooting the cylinder liner and oil radiator.
4, cylinder head damage:
After the cylinder head of diesel engine is cracked, even if there is only a small crack, coolant will leak into the cylinder and oil pan from the crack when the diesel engine is working. Generally, the cylinder head is not damaged. To know whether it is intact, you can check it with 7kg of compressed air. Once the damage is found, it should be replaced immediately.
In the process of using Cummins diesel generator set, if the oil is found to be milky white, it must be stopped for careful inspection and repair, and the work can continue after troubleshooting. Otherwise, diesel oil may have some vicious mechanical accidents such as cylinder pulling, cylinder pulling and even crankshaft locking due to poor lubrication.