Top 5 Common Hydraulic Power Unit Problems and How to Solve Them

Hydraulic power packs can overheat, lose pressure, slow down, or become noisy for a handful of common reasons. Use the checks below to pinpoint likely causes and prevent repeat failures.

Why is my hydraulic power pack overheating, and how can I prevent it?

Overheating is common and usually comes down to fluid issues, airflow/cooling problems, or the unit working harder than it should.

1. Low hydraulic fluid levels
   Low oil can allow air into the system and make the pump work harder, increasing friction and heat. Check and maintain the recommended level, top up when needed, and inspect the reservoir for leaks.
2. Poor fluid quality
   Dirt, moisture, and degraded oil reduce lubrication and heat dissipation, increasing friction. Change oil at the recommended intervals, use the correct grade, and maintain filtration to keep contaminants out.
3. Inadequate or blocked airflow
   Poor ventilation or blocked vents trap heat around the unit. Keep the power pack in a well-ventilated area, clean vents regularly, and avoid enclosed spaces where heat can build up.

What causes insufficient power output in a hydraulic power pack?

Low power output usually comes from air ingress, low oil, incorrect sizing, or overloading.

1. Air in the system
   Air pockets can cause cavitation and efficiency loss. Bleed the system, check suction-side connections, and ensure the reservoir is sealed correctly to prevent air intake.
2. Low hydraulic fluid levels
   Low oil reduces pressure and flow, causing weak performance. Maintain correct reservoir levels and investigate any ongoing loss of fluid.
3. Incorrect pump or motor size
   An undersized pump/motor won’t meet the required flow/pressure demands. Confirm the pack is correctly sized for the application and verify pump and motor specs match the system requirement.
4. Overloaded system
   Exceeding rated limits can reduce output and accelerate wear. Operate within the unit’s rated capacity and review load requirements.

Why is my hydraulic power pack operating slowly?

Slow operation is often caused by low flow, low pressure, air ingress, or worn components.

1. Air in the system
   Cavitation or aeration disrupts flow and can slow actuator response. Bleed the system and check seals/joins on the suction side.
2. Low hydraulic fluid levels
   Low oil causes pressure/flow loss, resulting in slow movement. Maintain correct fluid levels and check for leaks.
3. Worn or faulty pump
   Pump wear reduces flow and pressure capability. Inspect for wear and replace worn parts (or the pump) if performance is degraded.
4. Incorrect pressure settings
   Relief valve settings that are too low (or a faulty valve) can limit system pressure. Verify settings and replace/repair faulty valves.

Why is my hydraulic power pack making excessive noise and vibrating?

Noise and vibration are often linked to air/cavitation, poor suction conditions, or loose components.

1. Air in the system
   Cavitation causes noise, vibration, and premature wear. Bleed the system and ensure it’s properly sealed.
2. Low hydraulic fluid levels
   Low oil can cause the pump to draw air, increasing noise and vibration. Top up and inspect for leaks.
3. Loose or misaligned components
   Loose pump/motor mounts, fittings, or misalignment can create vibration. Tighten, realign, and replace worn mounts or fittings if needed.
4. Overloaded system
   Excess load strains components and increases noise. Operate within rated capacity and confirm correct sizing.

Why is my hydraulic power pack not generating enough pressure?

Low pressure can come from priming issues, suction leaks, internal leakage, or relief valve problems.

1. Gear pump not priming
   Ensure the suction filter is fully submerged in oil.
   • Double-Acting (D/A): Remove the relief valve and run the pump briefly until fluid exits the port, then refit the relief valve.
   • Single-Acting (S/A): Follow the same process, but remove the check valve instead.
2. Loose inlet connection on the gear pump
   Inspect and tighten suction-side fittings/hoses. Even small air leaks can prevent pressure build-up.
3. Damaged O-rings on relief or directional valves
   Directional valve leaks may show external oil loss, but relief valve O-ring issues can be internal and harder to spot. Inspect seals and replace if worn.
4. Pressure relief valve (PRV) fault
   A broken spring or contamination can wedge the PRV open, dumping flow back to tank. Clean/inspect the PRV and replace if needed.

By keeping your hydraulic power pack well-maintained and operating under optimal conditions, you can minimise overheating risk and extend the lifespan of the unit.