Reciprocating Pumps Trouble Shooting Guide

1. Air or vapor pocket in inlet line
2. Capacity of charge pump less than capacity of power pump
3. Air or vapor trapped in or above inlet manifold
4. Air leak in liquid supply piping system
5. Loose bolts in pump inlet manifold
6. Air or gases entrained in liquid
7. Foreign object holding pump inlet or discharge valve(s) open
8. Incorrect drive ratio
9. Loose belts
10. Incorrect motor or engine speed
11. Loose valve covers or cylinder head
12. Worn valves and seats
13. Safety relief valve partially open, or not holding pressure
14. Worn liners, piston rings or plungers
15. Bypass valve open, or not holding pressure
16. Blown liner gasket
17. NPSHA not sufficient
18. Liquid bypassing internally
19. Foreign object blocking liquid passage
20. Vortex in supply tank
21. Insufficient power delivered by motor

1. Inlet line partially clogged
2. Liquid vapor pressure too high
3. Liquid pumping temperature too high
4. Restricted inlet pipe fittings
5. Inlet line too long
6. Too many pipe fittings
7. Too small inlet line
8. Too low static inlet head
9. Too low atmospheric pressure

1. Pump not primed
2. Air or vapor pocket in inlet line
3. Clogged inlet line
4. All inlet valves propped open
5. All discharge valves propped open
6. Loose bolts in pump inlet manifold
7. Too high valve velocities

1. NPSHA too low
2. Liquid NOT Delivered to Pump Inlet Connection
3. Excessive Stuffing Box Leakage
4. NPSHR too high

1. Over Recommended Pressure
2. Loose Cylinder Head/Valve Cover
3. Damaged Gasket/O-ring

1. Water Condensation
2. Worn seals
3. Clogged Air Breather(s)
4. Worn Crankcase Packing
5. Loose Covers

1. Oil Level/Temperature Too High
2. Worn seals
3. Worn Crankcase Packing
4. Loose Crankcase Cover

1. Pump Running Backward/RPM too low
2. Insufficient Oil in Power End
3. Excessive Oil in Power End
4. Incorrect Oil Viscosity
5. Operating Pump above Recommended Pressure 6) Main Bearings too Tight
6. Drive Misaligned
7. Belts too Tight
8. Discharge Valve, one or more, Stuck Open 10) Insufficient Cooling
9. Pump RPM too Low
10. Inadequate Ventilation
11. Liquid End Packing Adjusted too Tight (adjustable style packing only)

1. Pump RPM too High
2. Low Voltage or other Electrical Trouble
3. Trouble with Engine, Turbine, Gear Reducer or other Related Equipment
4. Excessive Discharge Line Pressure
5. Clogged Discharge Line
6. Closed/Throttled Valve in Discharge Line
7. Incorrect Plunger/Piston Size for Application
8. Improper Bypass Conditions
9. Over-tightened Stuffing Box Glands on Adjustable Packing

1. Worn Packing
2. Worn rods or plunger
3. Worn stuffing boxes
4. Wrong size packing
5. Worn O-ring seal (replaceable boxes)

1. Excessive discharge pressure
2. Improper torquing of nuts
3. Shock overload caused by pump cavitation

1. Broken or weak valve spring
2. Pump cavitation
3. Air leak in inlet piping or loose bolts in pump inlet manifold
4. Air trapped above inlet valve

1. Piping inadequately supported
2. Inlet line too long or too small in diameter
3. Too many bends in inlet line
4. Multiple pump installations operating in phase
5. Obstruction Under Valve(s)
6. Packing Worn
7. Operating Above Recommended Pressure or RPM 8) Low NPSHA

*Be sure to differentiate between liquid knock and mechanical knock – very few knocks are mechanical on new installations.

1. Piston or plunger loose
2. Valve noise amplified through power end
3. Pump cavitation
4. Liquid knock
5. Air leak in inlet piping
6. Loose bolts in pump inlet manifold
7. Hydraulic noise in liquid end
8. Loose or worn crosshead pins and bushings
9. Loose connecting rod cap bolt
10. Worn connecting rod bearings
11. Worn crosshead
12. Main bearing end play excessive
13. Worn gears or chains
14. Gears or chains out of line
15. Pump running backward
16. Partial loss of prime
17. Shocks in piping system
18. Water in power end crankcase
19. Poorly supported piping, abrupt turns in piping, piping misaligned, pipe size too small