Problems on this page:
Flow or pressure falling
Hits OEE: Performance
Symptoms: The pump delivers less flow or cannot build the pressure it used to.
Gears, bushings or side plates worn
Measure the internal clearances at the next planned stop and rebuild the pump.
Relief valve opening early or leaking
Check the relief valve setting and its seat.
Suction restricted
Check the suction strainer and line for blockages.
Fluid viscosity lower than design
Check the fluid temperature and grade; thin fluid slips back through the gears.
Prevention: Flow or pressure at a set speed trended so wear shows early.
Noise and vibration
Hits OEE: Availability
Symptoms: The pump whines, rattles or vibrates more than usual.
Cavitation from low suction pressure
Check the suction line, the strainer and the fluid level.
Air drawn in at the suction
Check suction joints and the shaft seal for air leaks.
Coupling misaligned
Check the alignment between pump and motor.
Bearings or bushings worn
Check the shaft for play.
Prevention: Vibration checked on a route.
Shaft seal leaking
Hits OEE: Availability
Symptoms: Fluid leaks at the shaft seal.
Seal worn or the wrong type for the fluid
Replace the seal with a type rated for the fluid and temperature.
Shaft scored at the seal face
Check the shaft surface and repair it or fit a sleeve.
Shaft play from worn bushings
Check the bushings.
Running dry at start-up
Prime the pump before starting.
Prevention: Seal leakage checked on a route.
Pump running hot
Hits OEE: Availability
Symptoms: The pump body or the pumped fluid gets hotter than normal.
Relief valve recirculating flow back to suction
Check whether the relief valve is lifting in normal running, and find what raises the pressure.
Discharge partly blocked or a valve closed
Check the discharge line, filters and valves.
Internal wear letting fluid slip back
Check the internal clearances at the next planned stop.
Fluid too viscous at start-up
Warm the fluid before starting where the process allows.
Prevention: Pump temperature checked on a route.
Pump will not prime
Hits OEE: Availability
Symptoms: The pump runs after start-up but moves no fluid.
Suction lift higher than the pump can handle
Check the installation against the maker suction limits.
Air leaking in at the suction
Check suction joints, the strainer lid and the shaft seal.
Pump started dry
Fill the pump casing before the first start.
Motor turning the wrong way
Check the rotation direction after any electrical work.
Prevention: Priming checked after every maintenance job on the pump.
Metering accuracy poor
Hits OEE: Quality
Symptoms: A metering gear pump delivers inconsistent amounts from batch to batch.
Internal wear increasing slip
Rebuild or replace the pump when the volume per turn falls outside the limit.
Fluid viscosity changing with temperature
Control the fluid temperature at the pump.
Speed control drifting
Check the drive speed against a tachometer or encoder.
Back pressure changing
Check the discharge for pressure changes from valves or nozzles.
Prevention: Dose checked by weight daily.
Contamination damage
Hits OEE: Availability
Symptoms: Particles in the fluid score the gears and side plates, and the pump wears out early.
No suction strainer or filter fitted
Fit a strainer or filter suited to the pump clearances.
Filter bypass open
Check the filter element and its bypass indicator.
Tank dirty
Clean the tank and check its breather.
Wear debris from another component
Check other components on the circuit for wear.
Prevention: Fluid cleanliness checked on the maintenance plan.
Motor overload
Hits OEE: Availability
Symptoms: The motor trips on overload when the pump runs.
Discharge pressure higher than design
Check the discharge pressure and the relief valve setting.
Fluid too viscous
Warm the fluid or check the grade.
Bearings or bushings seizing
Turn the pump by hand with the motor isolated and check for stiffness.
Motor too small for the duty
Check the motor rating against the pump duty point.
Prevention: Motor current trended so rising load shows before a trip.
Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.
Related equipment guides: centrifugal pump · hydraulic system · lubrication system · metering pump · mechanical seal
Stop the same fault coming back
Recurring gear pump stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.
Book a Fabrico demo
The directory stays free.
Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary
Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover