Troubleshooting Pumps
Tech Talk 05/08/00
Table of Contents
Symptom: Noisy Pump
- Check for vacuum leaks in the suction line, or vacuum leaks in the pump
shaft seal if the pump is internally drained. Flooding connections with the
fluid being pumped may cause the noise to stop or abate momentarily, which
will locate the air entry point.
- Check alignment with drive mechanism; misalignment will cause wear and
high operating noise.
- Check for wear possibilities in manufacturer's specs.
- Check compatibility of fluid being pumped with manufacturer's
recommendations.
- Use reliable gauge to check operating pressure. Relief valve may
have been set too high. Check various unloading devices to see that
they are properly controlling the pump delivery.
- Aeration of fluid in reservoir (return lines above fluid level).
- Worn or sticking vanes, cam ring, worn or damaged gears and housing, or
worn or faulty bearing.
- Reversed rotation.
- Cartridge installed improperly.
- Plugged or restricted suction line or suction strainer or reservoir filter
breather.
- Oil viscosity too high or operating temperature too low; oil pour point
too high.
- Air leak in suction line or fittings causing irregular movement of control
circuit.
- Loose or worn pump parts; pump being driven in excess of rated speed; air
leak at pump shaft seal.
- Oil level too low; air drawn in through inlet pipe opening; air bubbles in
intake oil.
- Suction filter or line too small.
- Pump housing bolts loose or not properly torqued.
- Drain port improperly positioned allowing air to be trapped in pump
housing.
Symptom: Pump Fails to Deliver Fluid
- Low oil level in reservoir.
- Oil intake pipe suction strainer plugged.
- Air leak in suction line preventing priming.
- Pump shaft turning too slowly.
- Oil viscosity or oil lift too high.
- Wrong shaft rotation; pump shaft or parts broken; dirt in pump.
Symptom: Oil Leak Around Pump
- Shaft seal worn.
- Suction pipe connection leaking.
- Pump housing bolts loose or improperly torqued.
- Case drain line too small or restricted (shaft seal leaking).
- Cracked housing; over pressurized.
Symptom: Excessive Pump Wear
- Abrasive dirt in the hydraulic oil being circulated through the system.
- Oil viscosity too low.
- System pressure exceeding pump rating.
- Pump misalignment or belt drive too tight.
- Air being drawn in through pump intake.
Symptom: Broken Pump Parts Inside Housing
- Seizure due to lack of oil.
- Excessive system pressure above maximum pump rating.
- Excessive torquing of housing bolts.
- Solid matter drawn in from reservoir wedged in pump.
- Lack of clearance between rotor and ring.
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