Case CX31B Mini Excavator Repair Manual

1. Engine is overloaded

1) Engine speed higher than the specified value

2) Pressure higher than the specified value

3) Seizure or damage of internal parts of the pump

1) Adjust the pump as per the specified value

2) Adjust the pump as per the specified value

3) Repair/replace the pump

2.Pump oil level is

extremely low or the

delivery pressure

does not increase

1) Reduction of engine speed

2) Failure of pump mounting coupling

3) Seizure or damage of internal parts of the pump

1) Adjust the speed

2) Repair/replace the pump/coupling

3) Repair/replace the pump

3. Abnormal sound or

vibration occurs

(Cavitation

phenomenon)

1) Low tank oil level

2) Air and water contamination in the hydraulic oil

3) Clogging on the suction strainer

4) Clogging on or throttling of the suction pipe

5) Damage of the caulking part of the piston shoe

6) Looseness of the pump mounting part

7) Coupling failure

1) Supply the hydraulic oil to the specified level

2) Retighten the bolts of the circuit,

especially those of the suction pipes

Replace the hydraulic oil contaminated with water

3) Clean/replace the suction strainer

4) Repair the suction pipe

5) Replace the cylinder barrel assembly

6) Fix the mounting part

7) Replace the coupling

4. Oil leakage occurs

1) Failure of the O-ring or packing

2) Looseness or tightening failure of the

plug

3) Oil leakage from the oil seal edge

1) Replace the O-ring or packing

2) Retighten the plug with the specified torque

3) Repair/replace the oil seal or shaft