1. Fault Symptoms Overview

The excavator shows sluggish operation and rapid hydraulic oil temperature increase (e.g., exceeding 80°C within 30 minutes), typically manifesting as: no boom/stick movement at idle, slow bucket action; even at 1750rpm working speed, movements remain weak, with oil temperature gauge rising sharply.

2. Core Fault Causes (3 Key Areas)

1. Inadequate Hydraulic System Pressure

• Clogged suction filter restricting pump oil intake, common in excavators without regular maintenance;

• Worn hydraulic pump components (plungers, valve plates) causing internal leakage;

• Low main/pilot relief valve pressure setting or valve spool sticking, leading to system pressure loss.

2. Deteriorated Hydraulic Oil Quality

• Contaminated oil (with metal shavings, moisture) or oxidized oil reduces viscosity and lubrication, accelerating pump wear.

3. Impact of Breaker Attachment

• Excavators with breakers running long hours may inhale dust through worn breaker seals, accelerating oil contamination and creating a "contamination-wear" cycle.

3. Ishikawa Excavator Troubleshooting Steps (5-Stage Process)

1. Pressure Testing

• Install main/pilot pressure gauges: idle pilot pressure 0.8MPa, working speed main pressure only 13MPa (standard 24.5MPa), pilot pressure 1.8MPa (standard 3.5MPa)—pointing to relief valves or pump issues.

2. Relief Valve Inspection

• Disassembled main/pilot valves showed no wear or sticking; pressure adjustment failed, ruling out relief valves.

3. Oil Condition Check

• Hydraulic tank revealed dark oil mixed with metal particles, indicating abnormal pump wear.

4. Hydraulic Pump Disassembly

• Found: worn pilot rotor pump with scoring, plunger pump components (plungers, valve plates) worn, swash plate tiles grooved—consistent with contamination-induced damage.

5. Assembly Replacement & System Cleaning

• Replaced hydraulic pump assembly, oil, and filters;

• Cleaned lines, tank, and control valves. Post-repair: pilot pressure 3.5MPa, main pressure 24.5MPa, oil temperature normalized.

4. Repair Key Takeaways

• Excavators with breakers should shorten oil change intervals (recommend 500 hours) and add return-line filters;

• For combined "slow movement + high temperature" faults, prioritize oil contamination and pump wear checks to avoid total assembly failure.