No oil in system.

Fill to full mark. Check system for leaks.

Oil low in reservoir.

Check level and fill to full mark. Check system for leaks.

Oil of wrong viscosity.

Refer to specifications for proper viscosity.

Filter dirty or plugged.

Drain oil and replace filters. Try to find source of contamination.

Restriction in system.

Oil lines could be dirty or have inner walls that are collapsing, cutting off oil supply. Clean or replace lines. Clean orifices.

Air leaks in suction line.

Repair or replace lines.

Dirt in pump.

Clean and repair pump. If necessary, drain and flush hydraulic system. Try to find source of contamination.

Badly worn pump.

Repair or replace pump. Check for problems causing pump wear such as misalignment or contaminated oil.

Badly worn components.

Examine and test valves, motors, cylinders, etc. for external and internal leaks. If wear is abnormal, try to locate the cause.

Oil leak in pressure lines.

Tighten fittings or replace defective lines. Examine mating surfaces on couplers for irregularities.

Components not properly adjusted.

Refer to machine technical manual for proper adjustment of components.

Relief valve defective.

Test relief valves to make sure they are opening at their rated pressure. Examine seals for damage that could cause leaks. Clean relief valves and check for broken springs, etc.

Pump rotating in wrong direction.

Reverse to prevent damage.

Excessive load on system.

Check specification of unit for load limits.

Hoses attached improperly.

Attach properly and tighten securely.

Slipping or broken pump drive.

Replace couplers or belts if necessary. Align them and adjust tension.

Pump not operating.

Check for shut-off device on pump or pump drive.