Pump Maintenance Reference Guide


Pump Maintenance

Diagnosis & Maintenance, UDOR USA Plunger Pumps

Problem Problem Cause Solution
Low Pressure Worn or Plugged Nozzle Replace or clean nozzle, of proper size.
Belt Slippage. Tighten or replace belt.
Air leak in inlet plumbing. Disassemble, reseal and reassemble.
Pressure Gauge inoperative or not registering accurately. Check with new gauge; replace worn or damaged gauge.
Relief / unloader valve stuck, partially plugged or improperly adjusted; valve seat worn. Repair / replace and adjust relief / unloader vavle; check for worn and dirty valve seats.
Inlet suction strainer clogged or improper size. Clean, use adequate size, check more frequently.
Worn seals. Abrasives in pumped fluid or severe cavitation. Inadequate water supply. Install and maintain proper filter. Replace seals. Check inlet water supply. Maximum 6" inlet vacuum.
Fouled or dirty inlet or discharge valves. Clean inlet and discharge valve assemblies.
Worn inlet or discharge valves. Replace worn valves.
Leaky discharge hose. Replace discharge hose.
Pump runs extremely rough, pressure very low Restricted inlet or air entering the inlet plumbing. Proper size inlet plumbing; check for air tight seal at fittings & filter.
Inlet restrictions and/or air leaks.
Stuck inlet or discharge valves.
Replace worn seals, clean out material in valves or replace worn valves.
Plugged inlet filter. Clean or replace filter.
Water leakage from under the manifold. Worn inlet seals, cracked plunger. Replace seals. Install new plungers.
Oil leak between crankcase and pumping section. Worn crankcase oil seals. Replace crankcase oil seals.
Oil leaking in the area of crankshaft. Worn crankshaft seal, bearing or case o-ring. Replace crankshaft seal, bearing or case o-ring.
Bad bearing. Replace bearing.
Excessive play in the end of the crankshaft. Worn bearing. Replace ball bearing.
Water in crankcase. May be caused by humid air condensing into water inside the crankcase. Change oil at 3 month or 500 hour intervals using Udor Lube (or SAE 30W non-detergent oil).
Worn or improperly installed inlet water seals. Replace seals. Follow proper installation procedures.
Oil leaking at the rear portion of the crankcase. Damaged or improperly installed inlet water seals. Replace sight glass, crankcase cover gasket or drain plug gasket.
Loud knocking noise in pump. Pulley loose in cranksaft. Check key and tighten set screw.
Broken or worn bearing. Replace bearings.
Frequently or premature failure of the packing Scored plungers.
Over pressure to inlet manifold.
Abrasive material in the fluid being pumped.
Excessive temperature of fluid being pumped.
Running pump dry.
Replace plungers.
Reduce inlet pressure. Maximum 75 PSI.
Install proper filtration on pump inlet plumbing.
Assure fluid inlet temperature are within specified range. Maximum 160 °F
DO NOT run pump without fluid.
Strong surging at the inlet and low pressure discharge. Foreign particles in the inlet or discharge valve or worn inlet and/or discharge valves. Replace worn valves.
Check supply tank for contamination. Install and regularly clean filter. Never pump abrasive fluids.

Udor Plunger Pump Service Guide

Replacing Pump Valves

  1. All inlet and discharge valves can be serviced without disrupting the inlet or discharge plumbing
  2. To service the valves, remove valve caps.
  3. Remove the valve assembly from the valve cavity.
  4. Remove o-ring into cavity.
  5. Only one valve kit is necessary to replace all the valves in the pump. The kit includes new o-rings and valve assemblies.
  6. Install o-ring into cavity.
  7. Insert valve assembly into valve cavity.
  8. Install valve cap and torque to specifications. NOTE: Use blue thread locker or equivalent on all valve caps.

Removing Pump Head

  1. Remove the bolts from the pump head.
  2. Separate the head from the crankcase. NOTE: It may be necessary to tap head lightly with a plastic or rubber mallet to loosen.
    CAUTION: Do not damage plungers when removing the head.
  3. The packing assemblies typically come off with the head. At this point, inspect ceramic plungers. Plunger surfaces should be smooth and free from scoring and cracks. IF NOT, replace plunger.

Replacing Ceramic Plungers

  1. Remove plunger nut or bolt, then remove plunger from piston rod.
  2. If slinger washer comes off with the plunger, be certain this is reinstalled or replaced before a new plunger is installed.
  3. Separate plunger bolt from plunger.
  4. Install new o-ring, Teflon back-up ring and washer on plunger bolt or stem. NOTE: A film of grease on the outside of the o-rings ensures a better installation.
  5. Carefully insert plunger bolt into plunger. NOTE: Use red thread locker or equivalent on al plunger nuts or bolts.
  6. Slide new plunger over the piston guide and torque to specifications.

Replacing Seal Kit

  1. Insert proper seal stack extractor tool or reversible pliers through seal retainer. Extract retainers, packings and spreader rings.
  2. Place proper insertion sleeve into cylinder and install plastic spreader ring into bottom of the cylinder. Insert high pressure seal into insertion sleeve and tap firmly into place. Remove insertion sleeve.
  3. Install long life ring on top of the high pressure seal and insert middle brass ring.
  4. Install the low pressure seal into upper brass ring, lightly grease the outer o-ring and insert into cylinder.
  5. Coat each plunger and seal stack with grease and carefully reinstall the pump head. NOTE: It may be necessary to tap pump head lightly with a plastic or rubber mallet. Install head bolts and torque to specifications.

Avoid Cavitation Damage

Can you identify and avoid cavitation? Cavitation is the formation and collapse of gaseous cavities in a liquid which causes severe wear or eroding of the metal surfaces in the pump.

The most obvious sign of cavitation is a hammering noise. This noise can be either consistent or intermittent depending upon the degree of cavitation and damage to the pump. Vibration of the pump and system will also be noticeable as the pump is starved of fluid. Eventually flow and and pressure will decrease.

It is important to carefully check your system during assembly and operation to avoid the serious damage that can be caused by cavitation.

Check your system for these conditions which may contribute to or directly cause, cavitation:

  • Inadequate inlet line size
  • Insufficient inlet flow or excessive suction
  • Excessive inlet line length
  • Rigid inlet plumbing
  • Too many elbows and / or fittings
  • Excessive temperature build-up of pumped fluid
  • Air leak in inlet plumbing
  • Agitation in supply reservior
  • Inadequate increase of inlet flow for fluids of greater specific gravity
  • Inadequate increase of inlet flow for higher temperature fluids
  • Clogged inlet filters