5 Quick fixes for slow hydraulics in excavators

Hydraulic systems are the heart of any excavator, and when movement becomes slow, productivity takes a major hit. Operators often panic when they notice slow boom lifting, sluggish bucket curling, or delayed swing motion. 

The good news is that many cases do not require a full rebuild. There are a few quick checks and fixes that can restore power before jumping to costly component replacements.

This article explains 5 practical and technical fixes that every fleet manager, mechanic, and machine operator should know. 

We will stick to real-world examples and specifications from common machines to help you identify and correct the issue safely and efficiently.

What causes slow hydraulics in excavators?

Before jumping into solutions, it is useful to know what typically goes wrong inside a hydraulic system. Slow response usually points to one of these core issues:

• Oil flow is reduced.

• Pressure is leaking internally or externally.

• Heat buildup is lowering fluid viscosity and performance.

• Electronic control fail-safes are limiting pump output.

• Wear in major components such as hydraulic pumps or main control valves.

Now let us move into the five fastest solutions mechanics perform in the field.

1. Check hydraulic oil condition and level

Insufficient or degraded hydraulic oil is the number one cause of slow excavator movements. Oil is responsible for power transmission, cooling, lubrication, and sealing clearances in pumps and cylinders.

What to check:

• Oil level using the sight glass or dipstick when the machine is on level ground and hydraulic temperature is normal.

• Oil color: milky oil means water contamination, dark oil means oxidation or burnt fluid.

• Viscosity compatibility: too thin causes leaks and low pressure, too thick restricts flow.

Example: The Volvo EC480DL requires ISO VG 46 hydraulic oil for most climates. Using a thicker grade in cold regions can slow the machine until oil warms up.

Quick fix:

• Top up to recommended level.

• Replace oil if contamination is detected.

• Warm up the machine properly before operation in winter.

2. Replace clogged hydraulic filters

Filters protect pumps and valves from abrasive particles. Once clogged, they restrict fluid flow significantly which leads to slow or jerky actuators.

Symptoms indicating filter restriction:

• High hydraulic temperature.

• Squealing pump noise.

• Slow travel, boom, or bucket functions at idle.

Makana often sees this issue in medium excavators like the Cat 320D and Kobelco SK350LC-10 when customers skip service intervals because the machine still "looks fine".

Quick fix:

• Replace both pressure and return line filters.

• Clean strainers inside the tank if equipped.

A filter replacement is inexpensive but prevents costly pump scoring and valve block damage.

3. Inspect hydraulic hoses and line connections for leaks

Even the smallest leak can drop pressure, especially in high-flow systems like those on Cat 349D or Komatsu PC850-8R1. Some leaks are visible, while others remain internal and silent.

What to check:

• Cracked or ballooning hoses.

• Loose fittings at cylinders or valve block.

• Leaking seals at quick couplers.

• Oil residue around pilot lines.

Quick fix:

• Tighten fittings to manufacturer torque value.

• Replace worn hoses immediately.

• After replacement, bleed air from the system.

Safety tip: Never run your fingers across leaks. High-pressure oil can penetrate skin and cause serious injury.

4. Adjust engine rpm and pump settings

Modern excavators use computer-controlled pumps. Low engine rpm, incorrect work mode, or faulty electrical signals can reduce pump displacement.

For example:

• The JCB 3DX Plus and many other loaders reduce pump output when idling to save fuel.

• The Volvo EC550EL uses load-sensing hydraulics so operator inputs directly affect flow demand.

Quick fix checklist:

• Confirm the machine is not in eco or fine mode during heavy digging.

• Check that rpm is at rated level when operating the boom.

• Reset the pump control settings if available in the monitor.

• Inspect solenoids and throttle sensors for proper response.

If a pump cannot swash to full displacement, the excavator will always feel underpowered.

5. Check cylinders and main control valve for internal leakage

When worn seals inside cylinders or spools allow oil to bypass internally, movement slows even though pressure seems normal.

Common scenarios:

• Boom drifts down in a parked Cat 426F2 backhoe loader.

• Bucket holds the load but the movement is slow.

• Swing function lag due to worn center joint seals.

Hydraulic leakage test:

• Fully extended cylinder.

• Shut off function.

• Observe drift over 3 to 5 minutes.

Quick fix:

• Rebuild cylinder seal kits.

• Repair or replace worn valve sections.

• Flush system after internal wear events to remove debris.

Skipping this step often leads to repeat failures.

Troubleshooting chart for slow hydraulics

This reference helps you quickly match symptoms with failed components.

Keeping this chart in the service truck saves hours during field repairs.

When should you consider deeper repairs?

Temporary fixes only go so far. When performance continues to drop, the issue might involve major components like pumps, center joints, or valve blocks.

Signs that a deeper repair is needed:

• Over 10 percent performance drop measured by cycle-time tests.

• Metallic debris detected in oil sampling.

• Abnormal pump whine at neutral.

• Rapid heat rise during light operation.

How to test hydraulics quickly before buying a used excavator?

A pre-purchase walkaround is not enough. Here are technical checks that take less than 15 minutes:

1. Cycle time test: Fully raise and lower the boom 3 times and compare with specs.

2. Drift test: Extend stick and bucket, then check if it drifts more than 50 mm in few minutes.

3. Travel power test: Drive straight up a small slope and watch for hesitation.

4. Hydraulic sound: Pump should sound smooth without vibration or squeal.

5. Oil temperature: Check for rapid heat rise which indicates internal leakage.

Machines listed on makana.com provide detailed specs so you can compare directly during the test.

FAQs

• Why does my excavator get slower when hot?

Oil thins as temperature rises. This reduces pressure and increases internal leakage, especially in worn pumps or cylinders. A cooling system check is also necessary.

• Is slow swing function related to the same issues?

Often yes. Swing uses a dedicated motor but relies on the same hydraulic supply. Blocked filters or valve wear commonly affect swing first.

• How often should hydraulic oil be changed?

Most OEMs recommend between 2000 to 5000 hours depending on working conditions. Dusty or high-heat environments require shorter intervals.

• Can using wrong oil type damage hydraulics?

Wrong viscosity can lead to pump scoring, cavitation, and delayed response. Always follow OEM viscosity charts for ambient temperature.

• Does machine age always mean slower hydraulics?

No. Well-maintained old excavators perform excellently. Performance drop is about maintenance, not age.