Cat High Pressure Plunger Pumps Diagnosis and Maintenance
In the high-pressure system, the most important step is to establish a complete regular maintenance, which depends on the different using conditions of each system. To reduce many potential issues occurred, check carefully necessary entrance to the situation and protective equipment before installing system. The following guidelines will help us to make sure the cause and remedy various operating accidents.
Problem CAUSE Solution
  Low pressure

 Nozzle damage

 Nozzle replacement
 Loose belts  Tighten  or replace belt
 Inlet pipe pieces leak  Use PTFE liquid or raw material band to fasten  

 device and hoses

 Gauge failed or inaccurate  Check with the new gauge, replace the damaged


 Relief valve clogged or improperly adjusted  Clean/ regulate relief valve,  replace the

 damaged bearing、valve and O-ring

 Water filter clogged or improper size  Clean the filter, choose suitable size of filter and

 regularly check

 Particles in the pump fluid medium  Install suitable filter system
 Water pipeline leak  Replace the water pipeline
 Sufficient supply of liquid medium  Pressurize Inlet and install C.A.T.
 Serious cavitation  Exanimate water input situation
 Seals aging  Replace with new seal repair kit, strengthen


 Inlet / outlet valve damaged, impurities or too dirty  Check filling pressure situation. If lower pressure,

 please re-pressurize or replace it

  Pulse damper  Pulse damper failure  
 Inlet/outlet valve clogged  Clean inlet/outlet valve and components, replace   if necessary.
  • The Bottom of pump head leak  Hi or low pressure seals abrasion  Replace seal repair kit and strengthen


   Bearing O-ring abrasion  Replace O-ring
  • Water seepage into the


 Humid air in the crankcase condensed into water  Install protective cover , replace lubricant clear


   Hi/low pressure seal abrasion  Replace seal repair kit and strengthen


  Abnormal sound    
  • Entrance components  Insufficient water supply  Check fluid supply, increase pip size , pressurize

 or install C.A.T.

     Check the shaft key and tighten screws
  • Bearing  Bearing old or damaged  Replace bearing
  • Pulley  Crankshaft pulley loose  Check the crankcase key and tighten screws
  Oil spill    
  • Front oil seal of crankcase  Front oil seal of crankcase aging  Replace front oil seal of crankcase
  • Oil seal and O-ring  Side oil seal of crankcase or O-ring aging  Remove bearing cover, replace the O-rings and oil


  • Drain nut  Drain nut loose or O-ring aging  Tighten drain nut or replace O-ring
  • Peep oil lens  Peep oil lens loose or gasket aging  Tighten peep oil lens or replace gasket
  • Back cover  Back cover loose or back cover O-ring aging  Tighten back cover screws or replace O-ring
  • Oil cap  Oil cap loose or Crankcase over-oiled  Tighten oil cap. Note crankcase oil level
Quite unstable Pump operation    
  • Entrance situation  Inlet limited or poor sealing fittings  Choose the correct inlet pipe pieces. Check and

 tighten seals

  • Pump valves  Entry / exit valve parts blocked  Clean out impurities or replace the valve repair kit
  • Pump Seals  High pressure or low pressure seal abrasion or leak  Replace seal repair kit, strength maintenance
  Seals aging  Piston or plunger scratched  Replace piston or plunger
 Too high water pressure  Decrease water pressure
 Particles or abrasive in the fluid medium         Install filtration system before watering into the

 pump and regular cleaning

 Pump fluid medium over-pressure or high


 Check fluid medium pressure and temperature
 Pump run dry  Do not run pump when insufficient liquid or

 without liquid

 Insufficient supply of fluid medium  Increase inlet diameter. Pressurize or install C.A.T.
 Pump head corrosion  Replace pump head. Check the chemical

 properties of the fluid medium