SOOSAN Hydraulic Breaker Troubleshooting: 8 Common Faults

Even well-maintained hydraulic breakers occasionally develop faults. Knowing how to quickly diagnose and address common problems minimizes downtime and prevents minor issues from becoming major repairs.

This troubleshooting guide covers the 8 most common faults reported on SOOSAN SB and SQ series hydraulic breakers, with step-by-step diagnosis and field solutions.

Before diagnosing any hydraulic breaker fault:

• Shut down the excavator and remove the ignition key
• Release hydraulic pressure by cycling the breaker control lever with the engine off
• Allow the breaker to cool — hydraulic oil and breaker components can be extremely hot
• Wear appropriate PPE — safety glasses, gloves, and steel-toed boots
• Never open hydraulic connections under pressure

Symptoms: The breaker is connected and the control is activated, but there is no impact action at all.

A. Hydraulic flow not reaching the breaker

• Check that the excavator's auxiliary hydraulic circuit is activated
• Verify the hydraulic flow direction — some excavators require the flow direction to be set correctly for breaker operation
• Check for kinked or blocked hydraulic hoses
• Inspect the quick-connect couplings — ensure they are fully engaged

B. Insufficient hydraulic flow or pressure

• Check excavator hydraulic pressure setting — must meet the breaker's minimum requirement (refer to your model spec sheet)
• Verify the excavator's auxiliary flow rate matches the breaker's requirement
• Test with a pressure gauge at the breaker inlet port

C. Nitrogen gas pressure too low

• Check the nitrogen gas pressure in the accumulator (refer to model spec for correct pressure)
• If pressure is below specification, recharge with dry nitrogen gas
• Never use compressed air or oxygen — fire and explosion hazard

D. Internal valve stuck or seized

• This requires disassembly by a qualified technician
• Often caused by contaminated hydraulic oil
• Flush the hydraulic system and replace the oil and filter before reassembly

Symptoms: The breaker fires but impact energy is noticeably reduced — breaking that previously took 30 seconds now takes several minutes.

A. Low nitrogen gas pressure

• This is the most common cause of reduced impact energy
• Check nitrogen pressure and recharge to specification
• Nitrogen pressure drops gradually over time — check every 3 months

B. Hydraulic flow or pressure below specification

• Measure inlet pressure and flow rate
• Compare to the breaker's minimum requirements
• Adjust excavator hydraulic settings if adjustable

C. Worn piston or cylinder

• Internal wear reduces the effective compression ratio
• Requires disassembly and measurement by a technician
• Typically occurs after 2,000+ hours without proper maintenance

D. Worn or incorrect chisel

• An excessively worn chisel tip reduces energy transfer to the material
• Replace the chisel and measure the improvement

E. Hydraulic oil too hot or wrong viscosity

• Oil above 80°C loses viscosity and reduces hydraulic efficiency
• Allow the system to cool and check oil grade

Symptoms: The breaker fires for a few seconds, stops, fires again — irregular and unpredictable impact rhythm.

A. Hydraulic flow fluctuation

• Check for air in the hydraulic system (foamy oil, erratic controls)
• Inspect suction line for leaks
• Check hydraulic oil level

B. Nitrogen pressure at the borderline

• Nitrogen pressure slightly below specification causes intermittent firing
• Recharge nitrogen to the correct pressure

C. Control valve wear

• Worn control valve causes inconsistent flow distribution
• Requires inspection and possible valve replacement

D. Contaminated hydraulic oil

• Particles in the oil can temporarily block valve passages
• Change the hydraulic oil and filter; flush the system

Symptoms: Hydraulic oil visible on the outside of the breaker body, dripping from the front head area or from around the cylinder.

A. Worn or damaged piston seals

• The most common source of oil leaks in the breaker body
• Requires disassembly and seal replacement
• Use genuine SOOSAN seal kits for correct material and dimensions

B. Damaged O-rings at port connections

• Check the hydraulic inlet and outlet port O-rings
• Replace damaged O-rings — these are field-replaceable without full disassembly

C. Cracked front head or cylinder

• Inspect the front head and cylinder body for cracks
• Cracks typically result from operating with a seized chisel or incorrect mounting
• Cracked components must be replaced — welding is not recommended

D. Loose through-bolts

• Loose through-bolts allow the cylinder to separate slightly, causing leaks at the joint faces
• Torque all through-bolts to specification using a torque wrench

Symptoms: Unusual vibration felt through the excavator cab, arm, or boom during breaker operation — beyond normal operating vibration.

A. Loose mounting bolts

• Check and torque all mounting bolts connecting the breaker to the bracket
• Loose mounting is the most common cause of excessive vibration transmission

B. Worn or damaged bracket bushings

• The bracket bushings absorb vibration between the breaker and excavator arm
• Inspect bushings for wear, cracking, or deformation
• Replace worn bushings — this is a critical safety item

C. Operating with chisel not in contact with material

• Never operate the breaker in free air — always keep the chisel pressed against the material
• Free-air firing causes extreme shock loads on the breaker and excavator

D. Incorrect excavator arm angle

• Operating with the arm at extreme angles (fully extended or fully retracted) increases vibration
• Maintain 90–110° angle between boom and arm during breaking

Symptoms: Hydraulic oil temperature warning light activates, or measured oil temperature exceeds 80°C during breaker operation.

A. Clogged hydraulic oil cooler

• Clean the cooler fins with compressed air or water
• Check for mud, debris, or oil coating on the cooler surface

B. Continuous operation without breaks

• Hydraulic breakers generate significant heat
• Allow 5–10 minute cooling breaks every hour of continuous operation
• In hot climates, increase break frequency

C. Low hydraulic oil level

• Low oil level reduces the system's heat capacity
• Check and top up the hydraulic oil reservoir

D. Incorrect oil viscosity

• Oil that is too thick generates more heat through internal friction
• Verify the oil grade matches the operating temperature range

E. Excessive back pressure in return line

• Kinked or undersized return hose restricts oil flow and generates heat
• Check return hose size matches the breaker's specification

Symptoms: The chisel does not slide freely in the front head — it sticks, binds, or requires force to move.

A. Insufficient lubrication

• The most common cause — chisel and bushing seize without adequate grease
• Apply penetrating oil to the chisel-bushing interface
• Allow time to penetrate, then work the chisel free manually
• Increase greasing frequency going forward

B. Worn or damaged bushing

• A worn bushing with irregular wear can grip the chisel
• Inspect the bushing and replace if worn beyond specification

C. Bent or deformed chisel

• Even slight bending causes the chisel to bind in the front head
• Replace the chisel — do not attempt to straighten a bent chisel

D. Debris in the front head

• Rock particles and debris can pack around the chisel
• Clean the front head bore thoroughly after removing the chisel

Symptoms: Unusual sounds during operation — metallic knocking, rattling, hissing, or grinding — beyond the normal impact sound.

Some faults require professional service and should not be attempted in the field:

• Internal seal replacement — requires clean environment and specialized tools
• Piston or cylinder replacement — precision measurement required
• Nitrogen gas recharging — requires proper equipment and training
• Control valve service — contamination-sensitive procedure
• Crack repair or structural damage — safety-critical assessment needed

The majority of hydraulic breaker faults are preventable with consistent maintenance:

• Daily greasing prevents chisel sticking and bushing wear
• Regular oil changes prevent contamination-related valve and seal failures
• Nitrogen pressure checks prevent weak impact and intermittent firing
• Bolt torque checks prevent vibration-related structural damage
• Correct operating technique prevents free-air firing damage

If you cannot resolve a fault using this guide, contact the SOOSAN technical support team:

• Email: [email protected]
• WhatsApp: +86 156 5385 1615
• Address: Korea Industrial Park, Fushan, Yantai, Shandong

Please provide your breaker model, serial number, hours of operation, and a description of the fault when contacting support. This allows our team to provide accurate diagnosis and parts recommendations.