Your Ultimate Guide to John Deere 290D Excavator Parts – Kyotechs

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.

Connecting the terminals of the same polarity of each battery together is called parallel connection. Its characteristics are: the voltage is the same as the voltage of a single battery, and the current flowing out is equal to the sum of the currents flowing out of each battery. (The voltage remains unchanged, and the current increases). Connecting the opposite-polarity terminals of each battery in sequence is called series connection. Its characteristics are: the total voltage is the sum of the voltages of each battery, and the current flowing out is the same as the current flowing out of each single battery. (The current remains unchanged, and the voltage increases).

Air entering the hydraulic oil will cause unstable system pressure, reduced pump efficiency and abnormal noise.

To check if the hydraulic system is functioning properly, observe the color and viscosity of the hydraulic oil, check the oil level in the hydraulic tank, look for leaks in the lines and fittings, and test the output pressure of the hydraulic pump.

Possible electrical issues, low hydraulic oil level, clogged filter, or internal pump failure.

Solution: Check electrical connections, refill hydraulic oil, clean or replace filter, inspect and repair or replace pump.