Mini-Excavator Parts: FAQs, Solutions & Tips | Kyotechs

Common faults of hydraulic pumps include insufficient pressure, hydraulic oil leakage, abnormal noise, system overheating and wear of internal pump components.

1.The climate is cold in winter, the ambient temperature is low, the viscosity of the engine oil increases, and the friction resistance of each moving part increases, which reduces the starting speed and makes it difficult to start.

2.The battery capacity decreases as the temperature drops, which further reduces the starting speed.

3.Due to the reduction in starting speed, the leakage of compressed air increases, and the heat dissipation of the cylinder wall increases, which greatly reduces the temperature and pressure of the air at the end of compression, and increases the delay period of diesel ignition. In severe cases, it may even fail to burn.

4.The viscosity of diesel at low temperatures increases, which reduces the injection speed. In addition, the swirl speed, temperature and pressure of the air at the end of compression are relatively low, which makes the atomization quality of the diesel injected into the cylinder poor, making it difficult to quickly form a good combustible gas with the air and ignite and burn in time, or even fail to ignite, resulting in difficulty in starting.

Abnormal noise may be caused by air entering the system, cavitation, internal component wear or hydraulic oil contamination.

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.

There are usually the highest and lowest oil level marks (MAX and MIN) on the inner wall of the oil filling port of each engine. This means that the oil level cannot exceed MAX or be lower than MIN.

A lower oil level, that is, a decrease in the amount of oil in the engine, will increase the oil load, causing the oil to become more seriously contaminated by heat, which not only weakens the lubrication performance, but also increases the fuel consumption. Because the less oil in the engine, the higher the oil temperature; and the higher the oil temperature, the greater the fuel consumption will be as the oil temperature rises. It is very dangerous to run the engine when the oil level is at the lowest point (MIN).

Keeping the oil level at the highest point (MAX) all the time will cause the oil to foam and lead to insufficient lubrication, resulting in serious wear. Foaming oil will also increase fuel consumption.

Therefore, it is recommended to keep the engine oil level between the MAX and MIN marks at a position close to one-third of the MAX.