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Reasons from the piston group
1. The piston ring gap is too small. If the opening gap, side gap or back gap of the piston ring is too small, the piston ring will be stuck due to heat expansion when the engine is working, and it will be pressed tightly against the cylinder wall, or the piston ring will be broken, which can easily pull out grooves on the cylinder wall.
2. The piston pin is out. Because the piston pin retaining ring is not installed or falls off or breaks, the piston pin will be out during movement, which can easily damage the inner wall of the cylinder and cause the cylinder to blow into the crankcase.
3. The piston cylinder gap is too small or too large. If the piston material is poor, the manufacturing size error is too large, or the piston is deformed after the piston pin is assembled, the matching gap between the piston and the cylinder is too small, and the piston is stuck after heat expansion, which will then damage the cylinder wall.
4. The piston ring is seriously carbonized. Excessive carbon deposits cause the piston ring to stick or bite in the ring groove. At the same time, carbon deposits are a hard abrasive that will grind into longitudinal grooves on the cylinder wall.
5. The piston is seriously off-cylinder. Due to the bending and twisting of the connecting rod, the parallelism and coaxiality deviations of the connecting rod journal, main journal, and piston pin seat are too large, causing the piston to be significantly off-cylinder, which will accelerate the wear of the piston ring, piston and cylinder wall and destroy the formation of the oil film.

Reasons for cylinder sleeves
1. The roundness and cylindricality tolerances of the cylinder sleeves exceed the allowable range, which greatly reduces the sealing of the piston and cylinder sleeves. The high-temperature gas in the cylinder flows down, destroying the oil film between the piston and the cylinder wall, and then causing cylinder pulling.
2. The cylinder sleeve is deformed during the assembly process. For example: the protrusion of the upper end surface of the cylinder sleeve is too large, and the cylinder sleeve is deformed after the cylinder head is installed; the cylinder sleeve water blocking ring is too thick, and the cylinder sleeve is deformed after being pressed into the body, which can easily cause cylinder pulling.

Reasons for use:
1. Whether the size of the cylinder sleeve used during assembly does not match the cylinder body and piston.
2. The air filter is not sealed, which makes the filtering effect worse. Dust, sand and other impurities in the air are sucked into the cylinder, forming abrasive wear. Tests show that if a few grams of dust are sucked in every day, the wear of the cylinder liner will increase by more than 10 times.

Check and clean the fuel filters, clean sediment from the fuel tank, inspect the fuel lines for blockages or leaks, and use appropriate cleaning agents to flush the fuel system.

Kobelco excavator maintenance tips 1: Cooling to prevent air blockage In high temperatures in summer, the engine is prone to air blockage due to high speed and difficult heat dissipation, which makes it difficult to start the engine after stopping for a few minutes. Once air blockage occurs, the excavator driver should stop the engine immediately to cool down and eliminate the fault.

Kobelco excavator maintenance tips 2: Observe the water temperature gauge at any time to prevent water shortage When driving in high temperature weather, always pay attention to checking the cooling water volume and the water temperature gauge. When water shortage is found, immediately idle the engine to cool down before adding water, and be careful not to open the radiator cap immediately to prevent burns.

Kobelco excavator maintenance tips 3: Prevent engine oil from deterioration Lubricating oil is easily diluted by heat, resulting in poor oxidation resistance, easy deterioration, and even causing faults such as burning of the bearing and the shaft. Therefore, the crankcase and gearbox should be replaced with summer lubricating oil, and the amount and quality of the lubricating oil should be checked frequently, and replaced in time.

Kobelco excavator summer maintenance tips 4: timely cleaning of engine surface oil If the external oil of the engine is too thick, it will affect the heat dissipation and bury the hidden danger of failure of various parts. You can use the high-pressure spray method to clean the engine parts with a cleaning agent that does not corrode the body parts.

Kobelco excavator summer maintenance tips 5: prevent the water tank water temperature from being too high In summer, the cooling water of Kobelco excavators evaporates and consumes quickly. You must add enough cooling water before leaving the vehicle, and check the water level frequently during work. For single-cylinder diesel engines without a water temperature gauge, always pay attention to the red mark height of the water tank float. If the float cannot be used normally, it should be repaired in time. If the boiling phenomenon occurs during work, do not add cooling water directly. Stop the work, slow down the generator, and slowly add cooling water after the water temperature drops to avoid cracks in the water tank when it is cold.

Kobelco excavator summer maintenance tips 6: Ensure the best oil supply time In summer, the oil supply time of Kobelco excavators should be adjusted. If the oil is supplied too early, the engine will make a knocking sound and sometimes reverse; the oil supply time should not be too late, otherwise the engine will work weakly.

When the engine is cold, check the coolant level through the level gauge of the coolant tank and add coolant if necessary.