SANY Crawler Hydraulic Excavator SY195C9, SY205C9, SY215C9, SY225C9. Service Manual

7-104

Troubleshooting

H-8 Bucket speed slow

Trouble

●

The bucket moves slowly.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of right

pilot valve (bucket

circuit)

●

Stop the engine. Perform troubleshooting while the engine is running
at high idle.

Bucket control lever

Pilot valve output pressure

"NEUTRAL"

0 {0}

Bucket CURL or Bucket DUMP

≥

3.5MPa

{36 kg/cm²}

Failure of pressure

sensor

●

Stop the engine. Perform troubleshooting while the engine is running
at high idle.

Check the pressure sensor by replacing it with a new one.

Malfunction of

bucket control valve

(spool)

Spool of bucket control valve may have malfunction. Check it directly.

Malfunction or

defective seal of

bucket control valve

(relief valve and

makeup valve)

Relief valve and makeup valve in bucket control valve may have mal-
function or defective seal. Check the valves directly.

Failure of bucket

cylinder

●

Stop the engine. Perform troubleshooting while the engine is running
at high idle.

Charge the bucket with a load of approximate 1260 kg. Cut off the oil
passage to the high-pressure side of the cylinder. Disconnect the cylin-
der from the main valve. Measure the displacement of piston for 15 min-
utes after the cylinder becomes stable. If the measured value is greater
than 10 mm, it is deemed that cylinder has a defective seal. For more
information on the measuring procedure refer to "Testing and Adjusting",
"Hydraulic Drift (Work Equipment) - Test".

7-105

Troubleshooting

H-9 Work equipment cylinders no response in separate operation

Trouble

●

Boom cylinder gives no response in separate operation.

●

Arm cylinder gives no response in separate operation.

●

Bucket cylinder gives no response in separate operation.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal

state

Cause

Standard value in normal state/Remarks on troubleshooting

1 Malfunction of pilot valve

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Work equipment control lever

Pilot valve output pressure

"NEUTRAL"

0 {0}

DIG or DUMP

≥

3.5MPa

{36 kg/cm²}

Failure of pressure sen-

sor

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Check the pressure sensor by replacing it with a new one.

Malfunction of control

valve (spool)

Spool of control valve may have malfunction. Check it directly.

7-106

Troubleshooting

H-10 Work equipment drifts excessively

Trouble (1)

●

The boom drifts at excessive speed.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Failure of boom cylinder

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Charge the bucket with a load of approximate 1260 kg. Cut off the
oil passage to the high-pressure side of the cylinder. Disconnect the
cylinder from the main valve. Measure the displacement of piston
for 15 minutes after the cylinder becomes stable. If the measured
value is greater than 10 mm, it is deemed that cylinder has a defec-
tive seal. For more information on the measuring procedure refer to
"Testing and Adjusting", "Hydraulic Drift (Work Equipment) - Test".

Failure of boom retain-

ing valve

Boom retaining valve or pilot valve may be worn or sluggish. Check
the valves.

Malfunction or defective

seal of boom control

valve (relief valve and

makeup valve)

The relief valve and the makeup valve in the boom control valve
may have a defective seal. Check the seals.

Failure of boom valve

spool

Spool of boom valve may be worn excessively. Check the spool.

7-107

Troubleshooting

Trouble (2)

●

The arm drifts excessively.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Failure of arm

cylinder

●

Stop the engine. Perform troubleshooting while the engine is running at
high idle.

Cut off the oil passage to the high-pressure side of the cylinder. Disconnect
the cylinder from the main valve. Measure the displacement of piston for 15
minutes after the cylinder becomes stable. If the measured value is greater
than 10 mm, it is deemed that cylinder has a defective seal. For more infor-
mation on the measuring procedure refer to "Testing and Adjusting", "Hy-
draulic Drift (Work Equipment) - Test".

Malfunction or

defective seal of

arm control valve

(relief valve and

makeup valve)

Relief valve or makeup valve of the arm control valve may be defective.
Check the valves directly.

●

The performance of seal can be judged by replacing it with another re-
lief valve or makeup valve. (Do not replace it with the boom-down relief
valve or makeup valve as their pressures are set differently.)

Failure of arm

retaining valve

Arm retaining valve or pilot valve may be worn or sluggish. Check the
valves.

Failure of arm

valve (spool)

Arm valve (spool) may be worn excessively. Check it directly.

Trouble (3)

●

The bucket drifts excessively.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in nor-

mal state

Cause

Standard value in normal state/Remarks on troubleshooting

Failure of bucket

cylinder

●

Stop the engine. Perform troubleshooting while the engine is running
at high idle.

Bucket control lever

Leakage from bucket cylinder

Bucket-in relief

20 ml/min

Defective seal

of bucket control

valve (relief valve

and makeup valve)

Seal of relief valve or makeup valve of bucket control valve may be defec-
tive. Check it directly.

●

The performance of seal can be judged by replacing it with another
relief valve or makeup valve. (Do not replace it with the boom-down
relief valve or makeup valve as their pressures are set differently.)

Defective seal

of bucket control

valve (spool)

Seal of bucket control valve spool may be defective. Check it directly.

7-108

Troubleshooting

H-11 Work equipment moves sluggishly

Trouble

●

Work equipment moves sluggishly.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value

in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of arm
regeneration valve

Regeneration valve of arm may have malfunction. Check it directly.

Malfunction of

control valve (relief

valve and makeup

valve)

Relief valve or makeup valve of control valve may have malfunction.
Check it directly.

●

For arm and boom, whether a valve has malfunction can be judged
by replacing it with another relief valve or makeup valve.

(Do not replace it with the boom-lower relief valve or makeup valve as
their pressures are set differently. )

Trouble

●

Other work equipment moves while single oil circuit of certain work equip-
ment is relieved.

Related information

●

Set the working mode to (S) in order to perform troubleshooting.

Possible causes and standard value in

normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Defective seal of

control valve

Seal of control valve may be defective. Check it directly.

H-12 Other work equipment moves while single oil circuit is relieved

7-109

Troubleshooting

H-13 Travel speed drops considerably while swinging and travelling

Trouble

●

Travel speed drops considerably in swinging plus travelling operation.

Related information

●

If the travel speed is low in only travelling operation, check

rst ac-

cording to H-15.

Possible causes and standard value in

normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Failure of straight
travel valve

The straight travel valve gives no response. Check the spool and the
logic oil circuit drain port.

7-110

Troubleshooting

H-14 Machine deviates during travel

Trouble

●

Machine deviates during travel.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of travel pilot

valve

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Travel control lever

Pilot valve output pressure

Forward

Reverse

3.5~3.9 MPa

{ 36~40 kg/cm²}

Difference occurs between

left and right output

0.4 MPa {4 kg/cm²}

Malfunction of pilot relief

valve

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Control lever

Control circuit source pressure

All levers in "NEUTRAL"

3.5~3.9 MPa

{ 36~40 kg/cm²}

Failure of regulator

Check the regulator by swapping the front and back regulators.

Sluggishness of proportion-

al solenoid valve

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Travel control lever

Proportional valve output pressure

Operate both control levers

≤

0.1 MPa

Sluggishness of travel con-

trol valve (spool)

Check the valve spool to see whether it works well.

Internal leakage of central

swivel joint

Check it by swapping the lines.

Malfunction of travel motor

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Travel control lever

Leakage of travel motor

Travel relief

27.2 ml/min

Failure of

nal drive

Final drive may have internal defect. Check it directly.

●

Internal defect of the

nal drive can be determined through

abnormal noise, abnormal heat, and metal powder or debris
contained in the oil drained.

Failure of travel pilot pres-

sure sensor

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Travel control lever

Pilot valve output pressure

Forward

Reverse

3.5~3.9MPa

{ 36~40 kg/cm²}

Difference occurs between

left and right output

0.4 MPa {4 kg/cm²}

Check the sensor by swapping it with another one.

7-111

Troubleshooting

H-15 Travel speed is low

Trouble

●

Machine travel speed is low.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of travel

pilot valve

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Travel control lever

Pilot valve output pressure

Forward

Reverse

3.5~3.9 MPa

{ 36~40 kg/cm²}

Difference occurs between left and

right output

≤

0.4 MPa

≤

{4 kg/cm²}

Malfunction of pilot

relief valve

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Control lever

Control circuit source pressure

All levers in "NEUTRAL"

3.5~3.9 MPa

{ 36~40 kg/cm²}

Failure of sensor

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Travel speed

Travel control lever

Reading on monitor

Operated

3.5~3.9 MPa

{ 36~40 kg/cm²}

Operated

3.5~3.9 MPa

{ 36~40 kg/cm²}

Check the sensor by replacing it with another one.

Malfunction of travel
control valve (spool)

Spool of travel control valve may have malfunction. Check it directly.

Malfunction of travel

control valve (make-

up valve)

The makeup valve in travel control valve may have malfunction. Check

it directly.

Failure of travel mo-

tor

Stop the engine. Perform troubleshooting while the engine is running at

high idle.

Travel control lever

Oil leakage of travel motor

Travel relief

27.2 ml/min

Failure of

nal drive

Final drive may have internal defect. Check it directly.

●

Internal defect of the

nal drive can be determined through abnor-

mal noise, abnormal heat, and metal powder or debris contained in
the oil drained.

Troubleshooting

H-16 Machine is not steered well or steering power is low

Trouble

●

Machine is not steered well or steering power is low

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of travel pilot

valve

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Travel control lever

Pilot valve output pressure

Both sides in "NEUTRAL"

0 {0}

Either side operated

3.5~3.9 MPa

{ 36~40 kg/cm²}

Malfunction of travel pilot

pressure sensor

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Travel control lever

Solenoid valve output pressure

Both sides operated

3.5~3.9 MPa

{ 36~40 kg/cm²}

Either side operated

3.5~3.9 MPa

{ 36~40 kg/cm²}

Malfunction of travel
control valve (spool)

Spool of travel control valve may have malfunction. Check it direct-
ly.

Malfunction of travel

control valve (makeup

valve)

The makeup valve in travel control valve may have malfunction.
Check it directly.

Failure of travel motor

(relief valve)

Seal of relief valve in travel motor may be defective. Check it di-
rectly.

●

The failure of seal can be determined by swapping the front
and back motors or the left and right motors.

Failure of travel motor

(check valve)

Seal of check valve in travel motor may be defective. Check it di-
rectly.

●

The failure of seal can be determined by swapping the front
and back motors or the left and right motors.

7-113

Troubleshooting

H-17 Travel speed cannot be changed

Trouble

●

Travel speed cannot be changed.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in

normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of travel

speed shifting solenoid

valve

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Travel speed

Travel control lever

Solenoid valve output

pressure

Operated

0 {0}

Operated

3.5~3.9 MPa

{ 36~40 kg/cm²}

Failure of travel motor (in

speed change)

Speed shifting assembly of travel motor may have malfunction.
Check it directly.

7-114

Troubleshooting

H-18 Travel system fails (only at one side)

Trouble

●

One side of the tracks cannot make a turn.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Defective seat of travel
control valve (makeup
valve)

Seat of makeup valve in travel control valve may have malfunction.
Check it directly.

Defective seat of travel
motor (relief valve)

Seat of relief valve in travel control valve may have malfunction.
Check it directly.

Defective seat of travel
motor valve (makeup
valve)

Seat of check valve in travel motor valve may have malfunction.
Check it directly.

Speed of travel motor
drops.

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Travel control lever

Leakage from travel motor

Travel relief

27.2 ml/min

5 Failure of

nal drive

Final drive may have internal defect. Check it directly.

●

Internal defect of final drive can be determined with abnormal
noise, overheat, and metal powder or debris contained in the oil
drained.

Defective pilot pressure
sensor

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Travel control lever

Pilot valve output pressure

Forward

Reverse

3.5~3.9MPa

{ 36~40 kg/cm²}

Difference occurs between left and
right output

0.4 MPa {4 kg/cm²}

Check it with swapping method.

7-115

Troubleshooting

H-19 Swing operation fails

Trouble (1)

●

Upper structure fails to swing in either direction.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of swing

motor (parking brake)

Parking brake of swing motor may have malfunction. Check it directly.

Improper adjustment

or malfunction of

swing motor (relief

valve)

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Swing relief pressure

Swing relief

25.5~28.5 MPa

{260~291 kg/cm²}

If oil pressure does not become normal after adjustment, swing motor
relief valve may have malfunction or internal defect. Check the relief
valve directly.

Failure of swing motor

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Leakage from swing motor

Swing relief

≥

10 ml/min

Failure of swing

mechanism

Swing mechanism may have internal defect. Check it directly.

●

Internal defect of swing mechanism can be determined with ab-
normal noise, overheat, and metal powder or debris contained in
the oil drained.

7-116

Troubleshooting

Trouble (2)

●

Upper structure only fails to swing in one direction.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in

normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of pilot

valve

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Left control lever

Pilot valve output pressure

"NEUTRAL"

0 {0}

Swing

≥

3.5MPa {

≥

36 kg/cm²}

Malfunction of swing

control valve (spool)

Spool of swing control valve may have malfunction. Check it directly.

Defective seal of

swing motor (makeup

valve)

Seal of makeup valve in swing motor may have defect. Check it directly.

●

Failure of the seal can be determined by swapping the right and left
makeup valves and check for any changes.

7-117

Troubleshooting

H-20 Swing acceleration poor or swing speed low

Trouble (1)

●

Swing acceleration is poor, or swing speed is low.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of swing

motor (parking brake)

Parking brake of swing motor may have malfunction. Check it directly.

Improper adjustment

or malfunction of

swing motor (relief

valve)

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Swing relief valve

Swing relief

25.5~28.5 MPa

{260~291 kg/cm²}

If oil pressure does not become normal after adjustment, swing motor
relief valve may have malfunction or internal defect. Check the relief
valve directly.

Failure of swing mo-

tor

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Leakage from swing motor

Swing relief

≤

10 ml/min

Clogging of brake

control lines

Disassemble, clean and check.

Troubleshooting

Trouble (2)

●

Swing acceleration is only poor on one side, or swing speed is
low.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in normal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of pilot

valve

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Pilot valve output pressure

"NEUTRAL"

0 {0}

Left swing

Right swing

≥

3.5MPa {

≥

36 kg/cm²}

Malfunction of swing

motor (pressure com-

pensation valve)

Pressure compensation valve of swing motor may have malfunction.
Check it directly.

Defective seal of swing

motor (makeup valve)

Seal of makeup valve in swing motor may have defect. Check it di-
rectly.

●

Swap the left and right makeup valves and observe the result in
order to determine whether the seal fails.

One-side leakage of

swing pilot pressure

sensor (shuttle valve)

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Pilot valve output pressure

"NEUTRAL"

0 {0}

Left swing

Right swing

3.5~3.9MPa {36~40 kg/cm²}

7-119

Troubleshooting

H-21 Upper structure overruns remarkably when it stops swinging

Trouble (1)

●

Upper structure overruns remarkably when it stops swinging in
both directions.

Related information

●

Set working mode to (S) and fuel control dial at position (10) to
carry out troubleshooting.

Possible causes and standard value in nor-

mal state

Cause

Standard value in normal state/Remarks on troubleshooting

Improper adjustment

or malfunction of swing

motor (relief valve)

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Swing control lever

Swing relief pressure

Swing relief

25.5~28.5 MPa

{260~291 kg/cm²}

If oil pressure does not become normal after adjustment, swing motor
relief valve may have malfunction or internal defect. Check the relief
valve directly.

2 Failure of swing motor

●

Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.

Control lever

Leakage from swing motor

Swing relief

≤

10 ml/min

Trouble (2)

●

Swing acceleration is only poor on one side, or swing speed is low.

Related information

●

Set the working mode at gear (10) of power mode (S) to perform
troubleshooting.

Possible causes and standard value in nor-

mal state

Cause

Standard value in normal state/Remarks on troubleshooting

Malfunction of pilot valve

●

Stop the engine. Perform troubleshooting while the engine is
running at high idle.

Swing control lever

Pilot valve output pressure

"NEUTRAL"

0 {0}

Left swing

Right swing

≥

3.5MPa {

≥

36 kg/cm²}

Malfunction of swing con-

trol valve (spool)

Spool of swing control valve may have malfunction. Check it direct-

ly.

Malfunction or defec-

tive seal of swing motor

(makeup valve)

Seal of makeup valve in swing motor may be defective. Check it
directly.

●

Swap the left and right makeup valves and observe the result
in order to determine whether the seal fails.

SANY Crawler Hydraulic Excavator SY195C9, SY205C9, SY215C9, SY225C9. Service Manual - page 30