Reciprocating Pumps Trouble Shooting Guide

Air or vapor pocket in inlet line

Capacity of charge pump less than capacity of power pump

Air or vapor trapped in or above inlet manifold

Air leak in liquid supply piping system

Loose bolts in pump inlet manifold

Air or gases entrained in liquid

Foreign object holding pump inlet or discharge valve(s) open

Incorrect drive ratio

Loose belts

Incorrect motor or engine speed

Loose valve covers or cylinder head

Worn valves and seats

Safety relief valve partially open, or not holding pressure

Worn liners, piston rings or plungers

Bypass valve open, or not holding pressure

Blown liner gasket

NPSHA not sufficient

Liquid bypassing internally

Foreign object blocking liquid passage

Vortex in supply tank

Insufficient power delivered by motor

Inlet line partially clogged

Liquid vapor pressure too high

Liquid pumping temperature too high

Restricted inlet pipe fittings

Inlet line too long

Too many pipe fittings

Too small inlet line

Too low static inlet head

Too low atmospheric pressure

Pump not primed

Air or vapor pocket in inlet line

Clogged inlet line

All inlet valves propped open

All discharge valves propped open

Loose bolts in pump inlet manifold

Too high valve velocities

NPSHA too low

Liquid NOT Delivered to Pump Inlet Connection

Excessive Stuffing Box Leakage

NPSHR too high

Over Recommended Pressure

Loose Cylinder Head/Valve Cover

Damaged Gasket/O-ring

Water Condensation

Worn seals

Clogged Air Breather(s)

Worn Crankcase Packing

Loose Covers

Oil Level/Temperature Too High

Worn seals

Worn Crankcase Packing

Loose Crankcase Cover

Pump Running Backward/RPM too low 2) Insufficient Oil in Power End

Excessive Oil in Power End

Incorrect Oil Viscosity

Operating Pump above Recommended Pressure 6) Main Bearings too Tight

Drive Misaligned

Belts too Tight

Discharge Valve, one or more, Stuck Open 10) Insufficient Cooling

Pump RPM too Low

Inadequate Ventilation

Liquid End Packing Adjusted too Tight (adjustable style packing only)

Pump RPM too High

Low Voltage or other Electrical Trouble

Trouble with Engine, Turbine, Gear Reducer or other Related Equipment

Excessive Discharge Line Pressure

Clogged Discharge Line

Closed/Throttled Valve in Discharge Line

Incorrect Plunger/Piston Size for Application

Improper Bypass Conditions

Over-tightened Stuffing Box Glands on Adjustable Packing

Worn Packing

Worn rods or plunger

Worn stuffing boxes

Wrong size packing

Worn O-ring seal (replaceable boxes)

Excessive discharge pressure

Improper torquing of nuts

Shock overload caused by pump cavitation

Broken or weak valve spring

Pump cavitation

Air leak in inlet piping or loose bolts in pump inlet manifold

Air trapped above inlet valve

Piping inadequately supported

Inlet line too long or too small in diameter

Too many bends in inlet line

Multiple pump installations operating in phase

Obstruction Under Valve(s)

Packing Worn

Operating Above Recommended Pressure or RPM 8) Low NPSHA

Piston or plunger loose

Valve noise amplified through power end

Pump cavitation

Liquid knock

Air leak in inlet piping

Loose bolts in pump inlet manifold

Hydraulic noise in liquid end

Loose or worn crosshead pins and bushings

Loose connecting rod cap bolt

Worn connecting rod bearings

Worn crosshead

Main bearing end play excessive

Worn gears or chains

Gears or chains out of line

Pump running backward

Partial loss of prime

Shocks in piping system

Water in power end crankcase

Poorly supported piping, abrupt turns in piping, piping misaligned, pipe size too small