Trouble shooting of the pump

Trouble shooting of the pump


Possible Cause

Corrective Action

Low Pressure












  1. Leakage discharge hose.
  2. Inlet suction strainer clogged or improperly sized.
  3. Belt slippage.
  4. Unloader Valve stuck, partially plugged or improperly adjusted valve seat Worn.
  5. Unloader valve is by passing


  1. Relief / Safety Valve stuck, partially plugged or improperly adjusted valve seat Worn.
  2. Air leak in inlet plumbing.


  1. Incorrect or worn nozzle.


  1. Worn inlet, discharge valve blocked or dirty.
  2. Worn packing, Abrasive in pumped in cavitations. Inadequate water.
  1. Replace discharge hose.
  2. Clean Strainer.


  1. Tighten or replace with correct belt.
  2. Clean and adjust Unloader valve ; check for Worn or dirty valve seats. (check Manual of Unloader valve)
  3. Make sure unloader is adjusted properly and by pass seat is nor leaking.
  4. Clean and adjust relief / safety valve; check for Worn or dirty valve seats.
  5. Disassemble, reseal and reassemble.
  6. Make sure nozzle is matched to the flow and pressure of the pump. If the nozzle is worn. Replace with nozzle of proper size.
  7. Replace inlet and discharge valve worn valves, valve seats.
  8. Install proper filter suction at inlet manifold must be limited to lifting less then 10 feet of water or 8.5 PSI vacuum.

Water leakage from under manifold.

  1. Worn packing or cracked plunger.
  2. Worn adopter o-rings.
  1. Install new packing or plunger.
  2. Install new o-rings.

Pump runs but produce no flow

  1. Pump is not primed.
  1. Flood suction then restart pump.

Oil Leakage from

  1. Crankcase Oil Seals
  2. Crankshaft Oil Seals and O-rings.
  3. Drain Plug.
  1. Bubble Gauge.


  1. Bearing Cover.
  1. Filler Cap.


  1. Worn crankcase oil Seals.
  2. Worn Crankshaft oil seals or o-rings on bearing cover.
  3. Loose drain plug or worn drain plug o-rings.
  4. Loose bubble gauge or worn bubble gauge gasket.
  5. Loose bearing cover or worn bearing cover o-rings.
  6. Loose filer cap or excessive oil in crankcase.


  1. Replace crankcase oil Seals.
  2. Remove bearing cover and/or replace o-ring or oil seals.
  3. Tighten drain plug or replace o-rings.
  4. Tighten bubble cover or replace o-rings.
  5. Tighten bearing cover or replace o-rings.
  6. Tighten filler cap. Fill crank case to specified capacity.

Water in oil

  1. Worn Plunger oil Seal.
  2. If oil condition is milky, but the oil level does not rise in crankcase, this is a sign of condensation only.
  1. Replace the oil seals.
  2. Change oil more frequently.

Frequent or Premature failure of the packing

  1. Overpressure to inlet manifold.


  1. Abrasive particles the fluid being pumped.
  2. Excessive pressure and/or temperature of fluid being pumped.
  1. Running pump dry.
  2. Striving pump of adequate liquid.


  1. Eroded manifold.


  1. Cracked , Damaged or Worn plunger 
  1. Reduce inlet Pressure as per specification. (1-2 Bar)
  2. Install proper filtration on pump inlet plumbing and clean regularly.
  3. Check Pressure and fluid inlet temperature; be sure they are within specified range.
  4. Do not run pump without water.
  5. Increase hose one size larger them inlet port size. Pressurize and install Captive Acceleration Tube.
  6.  Replace manifold and check liquid compatibility.
  7. Replace Plunger.

Pump looses prime chattering noise, pressure fluctuates.

  1. Air leak in suction hose or inlet.



  1. Clogged suction strainer.
  2. Worn out Coupling Spider or Bush.
  1. Remove suction line and inspect it for a loose liner or debris lodged in hose. Avoid all unnecessary bends Do not kink hose.
  2. Clean Strainer.
  3. Replace Spider or Bush.

Pump fails to prime

  1. Air is trapped inside pump
  1. Disconnect discharge hose from pump. Flood suction hose, restart pump and run pump until all air has been evacuated.

Pump runs extremely rough,

  1. Inlet conditions.
  1. Pump valves.
  2. Pump seals.


  1. Restricted inlet or air entering the inlet plumbing.
  2. Stuck inlet or discharge valve.
  3. Leaking V-packing, High pressure or low pressure seals.


  1. Proper size inlet plumbing. Check for airtight seal
  2. Replace Worn valves.
  3. Install new seal kit. Increase frequency or service.

Loud knocking noise in pump

  1. Inlet supply.
  1. Bearing


  1. Inadequate inlet liquid supply


  1. Broken or Worn bearing


  1. Check liquid supply. Increase line size, pressurize or install C.A.T.
  2. Replace bearing.

Pressure Gauge fluctuates

  1. Valves worn or blocked by foreign bodies.
  2. Packing worn
  1. Clean or replace valves.


Short bearing life

  1. Pump-motor connection problem.


  1. Oil has been not changed on regular basis.
  2. Excessive pressure of the pumped water.
  1. Check Condition of the keys. Flexible coupling or pulley.
  2. Change oil as recommended in the installation and operating instruction.
  3. Check the pressure.

Slight leak, oil leaking in the area of crankshaft

  1. Worn Crankshaft seal or improperly installed oil seal o-ring.


  1. Bad Bearing.
  1. Remove oil seal retainer and replace damaged o-ring and/or seals.
  2. Replace Bearing.

Excessive play in the end of the crankshaft pulley.

  1. Worn main bearing from excessive tension on drive belt.
  1. Replace crankcase bearing and/or tension drive belt.


  1. Wrong Oil
  2. Low Oil Level
  3. Old Oil
  4. Contaminated Oil
  5. Oil Breakdown
  1. Use Recommended Oil
  2. Fill Oil above min. level
  3. Use new oil.
  4. Use decontaminated oil