Troubleshooting the High Pressure Water Pump

Problem Cause Remedy
Pulsation Valve stuck open. Check all valves, remove foreign matter.
Low pressure Worn nozzle. Replace nozzle, use proper size.

Air leak in inlet plumbing. Disassemble, reseal and reassemble.

Relief valve stuck, partially plugged or improperly valve seat worn. Clean, adjust relief valve; check for worn and dirty valve seats. Kit available.

Inlet suction strainer clogged or improperly sized. Clean; use adequate size. Check more frequently.

Worn packing. Abrasives in pumped fluid or severe 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 valve. Clean inlet and discharge valve assemblies.

Worn inlet, discharge valve blocked or dirty. Replace worn valves, valve seats and/or discharge hose.

Leaky discharge hose.
Pump runs extremely rough, pressure very low Inlet restrictions and/or air leaks. Stuck inlet or discharge valve. Replace worn cup(s), clean out foreign material, replace worn valves.

Restricted inlet or air entering the inlet plumbing. Proper size inlet plumbing, check for air tight seal.
Water leakage from under manifold. Slight leakage Worn packing. Install new packing.

Cracked plunger. Replace plunger(s)
Oil leak between crankcase and pumping section. Worn crankcase piston rod seals. O-Rings plunger retainer worn. Replace crankcase piston rod seals. Replace O-Rings
Oil leaking in the area of the crankshaft Worn crankshaft seal or improperly install oil seal O-Ring. Remove oil seal retainer and replace damaged O-Ring and/or seals.

Bad bearing. Replace bearing and any spacer or cover damaged or cover damaged by heat.
Water in the crankcase May be caused by humid air condensing into water inside the crankcase. Change oil intervals. Use SAE 30 non-detergent oil.

Worn packing and/or piston rod sleeve, O-Rings on plunger retainer worn. Replace packing. Replace O-Rings.

Cracked plunger. Replace plunger(s)
Oil leaking from underside of crankcase Worn crankcase piston rod seals. Replace seals

Scored piston rod. Replace piston rod.
Oil leaking at the rear portion of the crankcase Damaged crankcase, rear cover O-Ring, drain plug O-Ring, or sight glass O-Ring. Replace cover O-Ring, drain plug O-Ring, or sight glass O-Ring.
Loud knocking noise in the pump. Pulley loose on the crankshaft. Check key and tighten setscrew.

Broken or worn bearing or rod(s). Replace bearing or rod(s).

Valve stuck open or shut, or not opening enough. Replace bad valve.
Frequent or premature failure of packing. Scored, damaged or worn plunger. Replace plungers.

Over-Pressure 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 pump. Reduce pressure.

Running the pump dry. Do not run the pump without water.

Upstream chemical injection. Use downstream chemical injection.