In nearly all instances, pressure washer pump failure is the result of improper installation or operation rather than normal wear. One of the most common causes of pump failure is improper or unnecessary service, often as a result of the operator attempting the service.
Each time the pressure pump is serviced, the chance of pump failure as a result of improper service increases. The operator should be left with no reason or desire to open the pump for service.
Usually requests for service are not made until the operation of the equipment has become so bad that it usually does not work.
"The high pressure pump is generally one of the most dependable and best constructed components in a high pressure cleaner. The well-engineered pump may be installed in a not-so-well engineered system." All pumps have wear parts, which eventually need to be replaced.
"In most cases, the high pressure pump is likely to outlast most other components as long as the pump is installed correctly and the system is operated properly." (This is a quote from The Universal Guide to High Pressure and Steam Cleaner Repair.)
|
Problem
|
Probable
Cause
|
Solution
|
| Oil
Leak Between Crankcase and Pumping Section |
Worn
crankcase piston rod seals. |
Replace
crankcase piston rod seals. |
| O-rings
on plunger retainer worn. |
Replace
o-rings. |
| Frequent
or Premature Failure Of the Packing |
Scored,
damaged or worn plunger. |
Replace
plungers. |
| Overpressure
to inlet manifold. |
Reduce
inlet pressure. |
| Abrasive
material in the fluid being pumped. |
Install
proper filtration on pump inlet plumbing. |
| Excessive
pressure and/or temperature of fluid being pumped. |
Check
pressures and fluid inlet temperature; be sure they are within specified
range. |
| Over
pressure of pumps. |
Reduce
pressure. |
| Ran
without water. |
Do
not run pump without water. |
| Pump
Runs but Produces no Flow |
Pump
is not primed. |
Flood
suction then restart pump. |
| Pump
Fails to Prime |
Air
is trapped inside pump. |
Disconnect
discharge hose from pump. Flood suction hose, restart pump and run
pump until all air has been evacuated. |
| Pump
Loses Prime, Chattering Noise, Pressure Thread Fluctuates |
Air
leak in suction hose or inlet fittings. |
Remove
suction line and inspect it for a loose liner or debris lodged in
hose. Avoid all unnecessary bends. Do not kink hose. |
| Clogged
suction strainer. |
Clean
strainer. |
| Low
Pressure at Nozzle |
Unloader
valve is bypassing. |
Make
sure unloader is adjusted properly and bypass seat is not leaking. |
| Incorrect
or worn nozzle. |
Make
sure nozzle is matched to the flow and pressure of the pump. If the
nozzle is worn, replace. |
| Restricted
intake. |
Refer
to above priming information. |
| Pump
is Noisy |
Pump
sucking air. |
Check
suction manifold. |
| Pressure
Gauge Fluctuates |
Valves
worn or blocked by foreign bodies. |
Clean
or replace valves. |
| Packing
worn. |
Replace
packing. |
| Pumped
liquid temperature too high. |
Reduce
temperature of pumped liquid. |
| Over
Pressure When Gun is Closed . |
Leaking
in unloader valve and incorrect setting. |
Control
the valve and set new pressure level. |
| Pulsation
|
Faulty
pulsation damper. |
Check
pre-charge; if low, recharge it or install a new one. |
| Low
Pressure |
Worn
nozzle. |
Replace
with nozzle of proper size. |
| Belt
slippage. |
Tighten
or replace with correct belt. |
| Air
leak in inlet plumbing. |
Disassemble,
reseal and reassemble. |
| Relief
valve stuck, partially plugged or improperly adjusted valve seat worn.
|
Clean
and adjust relief valve; check for worn or dirty valve seats. Kit
available. |
| Inlet
suction strainer clogged or improperly sized. |
Clean.
Use adequate size. Check more frequently. |
| Worn
Packing. Abrasives in pumped in cavitation. Inadequate water. |
Install
proper filter. Suction at inlet manifold must be limited to lifting
less than 20 feet of water or 8.5 psi vacuum. |
| Fouled
or dirty inlet or discharge valves. |
Clean
inlet and discharge valve assemblies. |
| Worn
inlet, discharge valve blocked or dirty. |
Replace
worn valves, valve seats and/or discharge hose. |
| Leak
in the discharge line. |
Repair
leak. |
| Pump
Runs Extremely Rough, Pressure Very Low |
Restricted
inlet or air entering the inlet plumbing. Proper size inlet plumbing;
|
Check
for air tight seal. |
| Inlet
restrictions and/or air leaks. Stuck inlet or discharge valve. |
Clean
out foreign material. Replace worn valves. Replace
worn cup or cups. |
| Water
Leakage From Under Manifold. Slight Leakage |
Worn
packing. |
Install
new packing. |
| Oil
Leaking in the Area of Crankshaft |
Worn
crankshaft seal or improperly installed oil seal o-ring. |
Remove
oil seal retainer and replace damaged o-ring and/or seals. |
| Bad
bearing. |
Replace
bearing. |
| Excessive
Play in the End of the Crankshaft Pulley |
Worn
main bearing from excessive tension on drive belt. |
Replace
crankcase bearing and/or tension drive belt. |
| Water
in Crankcase |
Humid
air condensing into water inside the crankcase. |
Change
oil intervals. Use any high grade automotive 30 weight non-detergent
oil. |
| Worn
packing and/or piston rod sleeve, o-rings on plunger retainer worn. |
Replace
o-rings.
Replace packing. |
| Oil
Leaking from Underside of Crankcase |
Worn
crankcase piston rod seals. |
Replace
seals. |
| Oil
Leaking at the Rear Portion
of the Crankcase |
Worn
crankcase piston rod seals. |
Replace
seals. |
| Loud
Knocking Noise in Pump |
Pulley
loose on crankshaft. |
Check
key and tighten set screw. |
| Broken
or worn bearing. |
Replace
bearing. |
