Top 5 Common Komatsu Excavator Problems & Solutions - June 15, 2025
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Understanding Common Issues in Komatsu Excavators
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Common Komatsu Excavator Problems and Their Solutions
【1】Komatsu Excavator Burning Engine Oil
Burning engine oil is a frequent concern for excavator operators. Here are three common causes:
Dirty excavator air filter
Excavator engine blow-by (窜气)
Improper or non-genuine excavator engine oil
Solutions:
Regularly clean and replace the excavator air filter.
Overhaul the excavator engine to address blow-by issues.
Use the correct, genuine excavator engine oil that matches your Komatsu model.
【2】Komatsu Excavator Slow or Weak Hydraulic System
A sluggish hydraulic system can significantly reduce productivity. Potential reasons include:
Poorly adjusted PC valve.
Faulty LS valve assembly.
Damaged PC valve assembly.
Failure in the hydraulic components of the pressure reducing valve output circuit.
Malfunctioning plunger pump.
Plunger pump servo piston failure.
Incorrectly adjusted main relief valve.
Poorly operating unloading valve.
Damaged main relief valve.
Solutions:
Adjust or overhaul the PC valve.
Inspect and repair the LS valve.
Overhaul the PC valve assembly.
Inspect or replace the hydraulic components in the pressure reducing valve output circuit.
Overhaul the plunger pump.
Inspect or replace the plunger pump servo piston.
Readjust the main relief valve.
Adjust or overhaul the unloading valve.
Repair the main relief valve.
【3】Komatsu Excavator Walking Drift (Running Off-Track)
An excavator that doesn't travel straight can be due to several factors:
Cause 1: Large Deviation During Normal Walking
Faulty pressure reducing valve.
Poorly operating main control valve spool.
Malfunctioning travel motor assembly.
Damaged LS valve.
Damaged PPC valve.
Faulty travel pressure compensation valve.
Solutions:
Inspect and repair the pressure reducing valve.
Inspect and repair the main control valve spool.
Overhaul the travel motor.
Inspect and repair the LS valve.
Inspect and repair the PPC valve.
Inspect and repair the travel pressure compensation valve.
Cause 2: Large Deviation Upon Startup
Poorly operating travel pressure compensation valve.
Clogged throttle orifice in the servo mechanism.
Solutions:
Inspect and repair the travel pressure compensation valve.
Clean or unclog the throttle orifice in the servo mechanism.
【4】Komatsu Excavator Weak Walking Power (Slow Speed)
After a period of use, many Komatsu excavator operators report a lack of power or slow speed during movement.
Faulty CO valve.
Faulty CO cancel solenoid valve.
Decreased main relief valve setting pressure.
Faulty 2-stage relief solenoid valve.
Solutions:
Inspect and repair the CO valve.
Inspect and repair the CO cancel solenoid valve.
Check if the main relief valve setting pressure has dropped.
Inspect and repair the 2-stage relief solenoid valve.
【5】Komatsu Excavator Cannot Move (Single Side)
A common issue is the inability of the excavator to move on one side during operation.
Poorly operating oil supply valve in the main control valve.
Faulty travel motor safety valve.
Malfunctioning final drive.
Damaged travel motor.
Solutions:
Inspect and repair the oil supply valve.
Inspect and repair the travel motor safety valve.
Inspect and adjust the final drive.
Repair or replace the travel motor.
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Glossary of Common Machinery Parts (Engineering Machinery, Heavy Trucks, Agricultural Machinery, Automobiles)
风扇泵 (Fan Pump): A hydraulic pump that drives the cooling fan in construction equipment. Example: 卡特彼勒 345D 风扇马达 (Caterpillar 345D Fan Motor / Гидромотор вентилятора Caterpillar 345D).
空气滤清器 (Air Filter): Cleans the air entering the engine, preventing dust and debris from causing damage. Example: 徐工 XE35U 空气滤芯 (XCMG XE35U Air Filter Element / Воздушный фильтр XCMG XE35U).
主操作阀 (Main Control Valve): Directs hydraulic fluid to different actuators, controlling the movement of the machine's components. Example: 小松 PC200-8 主控阀 (Komatsu PC200-8 Main Control Valve / Главный распределительный клапан Komatsu PC200-8).
行走马达 (Travel Motor): Hydraulic motor that drives the tracks or wheels, enabling the machine to move. Example: 沃尔沃 EC220D 行走马达 (Volvo EC220D Travel Motor / Ходовой гидромотор Volvo EC220D).
液压泵 (Hydraulic Pump): Converts mechanical power into hydraulic power, supplying pressurized fluid to the hydraulic system. Example: 三一 SY215 液压主泵 (Sany SY215 Main Hydraulic Pump / Главный гидравлический насос Sany SY215).
油缸 (Hydraulic Cylinder): A linear actuator that uses hydraulic power to produce force in a linear motion. Example: 柳工 CLG856 装载机 铲斗油缸 (Liugong CLG856 Loader Bucket Cylinder / Гидроцилиндр ковша погрузчика Liugong CLG856).
发动机总成 (Engine Assembly): A complete engine unit, including all its components. Example: 五十铃 4HK1 发动机总成 (Isuzu 4HK1 Engine Assembly / Двигатель в сборе Isuzu 4HK1).
轮胎 (Tire): A pneumatic tire used on heavy trucks and agricultural vehicles. Example: 米其林 重卡 轮胎 (Michelin Heavy Truck Tire / Шина для грузовых автомобилей Michelin).
离合器 (Clutch): A mechanical device that engages and disengages power transmission, commonly used in agricultural machinery and automobiles. Example: 约翰迪尔 拖拉机 离合器片 (John Deere Tractor Clutch Disc / Диск сцепления трактора John Deere).
齿轮箱 (Gearbox): A mechanical component that transmits power and adjusts the speed and torque output. Example: 中国重汽 豪沃 变速箱 (Sinotruk Howo Gearbox / Коробка передач Sinotruk Howo).
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运营方案由 广数供应链（CGSC） 团队提供
Summary of Common Komatsu Excavator Problems and Solutions
| Problem | Possible Causes | Solutions |
|---|---|---|
| Burning Engine Oil | Dirty air filter, engine blow-by, improper oil | Clean/replace air filter, repair engine, use correct oil |
| Slow/Weak Hydraulics | PC valve, LS valve, plunger pump issues, main relief valve | Adjust/repair PC valve, inspect LS valve, overhaul pump, readjust relief valve |
| Walking Drift | Pressure reducing valve, control valve spool, travel motor, LS/PPC/compensation valve | Repair valves, overhaul motor |
| Weak Walking Power | CO valve, CO cancel solenoid, low relief pressure, 2-stage relief valve | Repair valves, check/adjust relief pressure |
| Cannot Move (Single Side) | Oil supply valve, travel motor safety valve, final drive, travel motor | Repair valves, inspect/adjust final drive, repair/replace motor |
