1. No or Slow Crane Movement

Possible Causes:

• Low hydraulic fluid level

• Pump failure (worn or broken internal parts)

• Clogged suction strainer or filter

• Pressure relief valve stuck open

• Pilot pressure failure (if applicable)

Troubleshooting Methods:

• Check and refill hydraulic fluid to the correct level.

• Measure pump output flow and pressure; replace pump if defective.

• Clean or replace the suction strainer and return filters.

• Inspect and adjust or replace the pressure relief valve.

• Verify pilot pump pressure and solenoid valve operation.

2. Overheating of Hydraulic Oil

Possible Causes:

• Continuous operation near relief valve setting

• Clogged cooler or radiator

• Low oil level causing poor heat dissipation

• Internal leakage (worn cylinders, motors, or valves)

• Wrong viscosity grade of hydraulic oil

Troubleshooting Methods:

• Avoid prolonged deadheading; adjust system settings.

• Clean the oil cooler fins and check cooling fan/motor.

• Top up oil to the recommended level.

• Test components for bypass leakage and repair/replace as needed.

• Drain and replace oil with correct viscosity per manufacturer specs.

3. Excessive Noise or Vibration

Possible Causes:

• Cavitation (air in the system)

• Worn pump bearings or gears

• Loose mounting bolts on pump or motor

• Sticking or damaged pressure relief valve

Troubleshooting Methods:

• Check suction line for leaks; tighten all suction connections.

• Replace worn pump components.

• Tighten all fasteners.

• Clean or replace the relief valve and check for chatter.

4. Load Drifting or Drooping

Possible Causes:

• Internal leakage in the lift cylinder piston seal

• Worn or stuck counterbalance valve

• Pilot check valve not sealing properly

• Control valve spool wear

Troubleshooting Methods:

• Perform cylinder drift test; repack cylinder if needed.

• Inspect and replace counterbalance valve.

• Disassemble and clean pilot check valve; replace if damaged.

• Replace valve section or spool.

5. Erratic or Jerky Movement

Possible Causes:

• Air trapped in the system

• Contaminated oil (water, particles)

• Failing proportional valve or feedback sensor

• Sticky control spools

Troubleshooting Methods:

• Bleed air from cylinders and high points.

• Take an oil sample for analysis; filter or replace oil.

• Check electrical signals and replace faulty proportional valve.

• Remove and clean spools; replace seals.

6. Low or No Pressure

Possible Causes:

• Pump not delivering flow

• Relief valve stuck open

• Broken line or severe external leak

• Pump drive failure (sheared coupling, broken shaft)

Troubleshooting Methods:

• Check pump rotation and coupling.

• Adjust or replace relief valve.

• Inspect all hoses and fittings; repair leaks.

• Replace drive coupling or pump.