Troubleshooting High Pressure Pumps

SymptonPossible CauseSolution
Oil leak between crankcase and pumping sectionWorn rod oil sealsReplace crankcase piston rod seals
Frequent or premature failure of the packingCracked, damaged or worn plungerReplace plungers
Overpressure to inlet manifoldReduce inlet pressure
Material in the fluid being pumpedInstall proper filtration on pump inlet plumbing
Excessive pressure and/or temperature of fluid being pumpedCheck pressures and fluid inlet temperature; be sure they are within specified range
Running pump dryDo not run pump without water
Pump runs but produces no flowPump is not primedFlood suction then restart pump
Pump fails to primeAir is trapped inside pumpDisconnect discharge hose from pump. Flood suction hose, restart pump and run pump until all air has been evacuated
Pump loses prime, chattering noise, pressure fluctuatesAir leak in the suction hose or inletRemove suction line and inspect it for a loose liner or debris lodged in the hose. Avoid all unnecessary bends. Do not kink hose
Clogged suction strainerClean strainer
Low pressure at nozzleUnloader valve is by-passingMake sure unloader is adjusted property and by-pass seat is not leaking
Incorrect or worn nozzleMake sure nozzle is matched to the flow and pressure of the pump. If the nozzle is worn, replace
Worn packing or valvesReplace packing or valves
Pressure gauge fluctuatesValves worn or blocked by foreign bodiesClean or replace valves
Seals wornReplace Seals
Low-pressureWorn nozzleReplace with nozzle of proper size
Belt slippageTighten or replace with correct belt
Air leak in inlet plumbingDisassemble, reseal and reassemble
Relief valve stuck, partially plugged or improperly adjusted valve seat wornClean and adjust relief valve; check for worn or dirty valve seats
Worn packing. Abrasive in pumped in cavitation. Inadequate waterInstall proper filter suction at inlet manifold must be limited to lifting less than 20 feet of water or 8.5 psi vacuum
Worn inlet, discharge valve blocked or dirtyReplace inlet and discharge valve
Pump runs extremely rough, pressure very lowInlet restrictions and/or air leaksClean out foreign material
Stuck inlet or discharge valveReplace worn valves
Water leakage from under manifoldWorn packing or cracked plungerInstall new packing or plunger
Slight leak, oil leaking in the area of crankshaftWorn crankshaft seal or improperly installed oil seal o-ringRemove oil seal retainer and replace damaged 0-ring and/or seals
Bad bearingReplace bearing
Excessive play at the end of the crankshaft pulleyWorn the main bearing from excessive tension on drive beltReplace crankcase bearing and/or tension drive belt
Water in crankcaseHumid air condensing into water inside the crankcaseChange oil intervals
Worn packing and/or cracked plungerReplace packing. Replace plunger
Loud knocking noise in pumpCavitation or sucking airCheck water supply is turned on
Pulley loose on crankshaftCheck key and tighten set screw
Broken or worn bearingReplace bearing

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