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DIAGNOSIS AND MAINTENANCE

One of the most important steps in a high pressure system is to establish a regular maintenance program. This will vary slightly with each 
system and is determined by various elements such as the duty cycle, the liquid being pumped, the actual specifications vs rated specifications
of the pump, the ambient conditions, the inlet conditions and the accessories in the system. A careful review of the necessary inlet conditions
and protection devices required before the system is installed will eliminate many potential problems.

CAT PUMPS are very easy pumps to service and require far less frequent service than most pumps. Typically, only common tools are required,
making in-field service convenient, however, there are a few custom tools, special to certain models, that do simplify the process. This service
manual is  designed to assist you with the disassembly and reassembly of your pump. The following guide will assist in determining the cause
and remedy to various operating conditions. You can also review our FAQ or SERVICE sections on our WEB SITE for more facts or contact
CAT PUMPS directly.

PROBLEM

PROBABLE CAUSE

SOLUTION

Low pressure

•Worn nozzle.

•Replace with properly sized nozzle.

•Belt slippage.

•Tighten belt(s) or install new belt(s). 

•Air leak in inlet plumbing.

•Tighten fittings and hoses. Use PTFE liquid or tape.

•Pressure gauge inoperative or not registering accurately.

•Check with new gauge. Replace worn or damaged gauge.

•Relief valve stuck, partially plugged or improperly adjusted.

•Clean/adjust relief valve. Replace worn seats/valves and o-rings.

•Inlet suction strainer (filter) clogged or improperly sized.

•Clean filter. Use adequate size filter. Check more frequently.

•Abrasives in pumped liquid.

•Install proper filter.

•Leaky discharge hose.

•Replace discharge hose with proper rating for system.

•Inadequate liquid supply.

•Pressurize inlet and install C.A.T. 

•Severe cavitation.

•Check inlet conditions.

•Worn seals.

•Install new seal kit. Increase frequency of service.

•Worn or dirty inlet/discharge valves.

•Clean inlet/discharge valves or install new valve kit.

Pulsation

•Faulty Pulsation Dampener.

•Check precharge. If low, recharge, or install a new dampener.

•Foreign material trapped in inlet/discharge valves.

•Clean inlet/discharge valves or install new valve kit.

Water leak
•Under the manifold

•Worn V-Packings, High Pressure or Lo-Pressure Seals.

•Install new seal kit. Increase frequency of service. 

•Worn adapter o-rings.

•Install new o-rings.

•Into the crankcase

•Humid air condensing into water inside the crankcase.

•Install oil cap protector. Change oil every 3 months or 500 hours.

•Excessive wear to seals and V-Packings.

•Install new seal kit. Increase frequency of service. 

Knocking noise
•Inlet supply

•Inadequate inlet liquid supply.

•Check liquid supply. Increase line size, pressurize or install C.A.T.

•Bearing

•Broken or worn bearing.

•Replace bearing.

•Pulley

•Loose pulley on crankshaft

•Check key and tighten set screw.

Oil leak
•Crankcase oil seals.

•Worn crankcase oil seals.

•Replace crankcase oil seals.

•Crankshaft oil seals and o-rings.

•Worn crankshaft oil seals or o-rings on bearing cover.

•Remove bearing cover and replace o-rings and/or oil seals.

•Drain plug

•Loose drain plug or worn drain plug o-ring.

•Tighten drain plug or replace o-ring.

•Bubble gauge

•Loose bubble gauge or worn bubble gauge gasket.

•Tighten bubble gauge or replace gasket.

•Rear cover

•Loose rear cover or worn rear cover o-ring.

•Tighten rear cover or replace o-ring.

•Filler cap

•Loose filler cap or excessive oil in crankcase.

•Tighten filler cap. Fill crankcase to specified capacity.

Pump runs extremely rough
•Inlet conditions

•Restricted inlet or air entering the inlet plumbing

•Correct inlet size plumbing. Check for air tight seal.

•Pump valves

•Stuck inlet/discharge valves.

•Clean out foreign material or install new valve kit.

•Pump seals

•Leaking V-Packings, High Pressure or Lo-Pressure seals.

•Install new seal kit. Increase frequency of service.

Premature seal failure

•Scored plungers.

•Replace plungers.

•Over pressure to inlet manifold.

•Reduce inlet pressure per specifications.

•Abrasive material in the liquid being pumped.

•Install proper filtration at pump inlet and clean regularly.

•Excessive pressure and/or temperature of pumped liquid.

•Check pressure and inlet liquid temperature.

•Running pump dry.

•DO NOT RUN PUMP WITHOUT LIQUID.

•Starving pump of adequate liquid.

•Increase hose one size larger than inlet port size. Pressurize and 

install C.A.T.

•Eroded manifold.

•Replace manifold. Check liquid compatibility.

Summary of Contents for 1851

Page 1: ...hich would be read at the discharge manifold of the pump NOT AT THE GUN OR NOZZLE Use PTFE thread tape or pipe thread sealant sparingly to connect accessories or plumbing E xercise ca ution not to wrap tape beyond the last threa d to avoid tape from becoming lodged in the pump or accessories This condition will cause a malfunction of the pump or system PRESSURE REGULATION All systems require both ...

Page 2: ...s 2 and 3 found under Disassembly for Discharge Valves 2 Using an allen wrench remove the Hex Socket Head Screws HSH from the VBM 3 Insert two M8x114 metric threaded bolts into the right and left servicing holes on the VBM face Thread in bolt until it makes contact with Inlet Manifold Continue threading until manifolds begin to separate Support underside of VBM to avoid possi ble damage to ceramic...

Page 3: ...nto valve chamber of Discharge Manifold with Spring Retainer facing down until completely seated 14 Support the VBM from the under side and slide manifold over Manifold Studs Apply anti seize to HSH screw threads and thread in hand tight Torque in sequence to specifications in torque chart 15 Support the Discharge Manifold from the under side and slide manifold over the Manifold Studs Install Flat...

Page 4: ...ilicone base lubricant NOTE For standard installation apply a small amount of oil to the outside edge of the LPS HPS VP MA FA and O Rings for ease of installation and to avoid damage Models 1861 1861K 1 Examine Lo Pressure Seals for wear to the internal ridges outer surfaces or for broken springs and replace as needed 2 Examine LPS Adapters for scale build up or wear and O Rings for cuts or deteri...

Page 5: ... 8 Examine Gaskets O Rings and Back up Rings for cuts or wear and replace as needed 9 Examine Plunger Retainers for wear or damaged threads and replace as needed Plunger arrangement 10 Install Gaskets first then O Rings and Back up Rings onto Plunger Retainers NOTE Lubricate O Rings and Back up Rings for ease in installation and to reduce possible damage 11 Apply Loctite 242 to exposed threaded en...

Page 6: ...Line size must be a minimum of one size larger than the pump inlet fitting Avoid tees 90 degree elbows or valves in the inlet line of the pump to reduce the risk of flow restriction and cavitation The line MUST be a FLEXIBLE hose NOT a rigid pipe and reinforced on SUCTION systems to avoid collapsing The simpler the inlet plumbing the less the potential for problems Keep the length to a minimum the...

Page 7: ...34 10 4 6 220 52 16 7 1 8 300 80 25 10 2 10 450 120 38 14 3 15 900 250 80 30 7 20 1600 400 121 50 12 25 650 200 76 19 30 250 96 24 40 410 162 42 50 600 235 62 60 370 93 At a fixed flow rate with a given size hose the pressure drop across a given hose length will be directly proportional A 50 ft hose will exhibit one half the pressure drop of a 100 ft hose Above values shown are valid at all pressu...

Page 8: ...If low recharge or install a new dampener Foreign material trapped in inlet discharge valves Clean inlet discharge valves or install new valve kit Water leak Under the manifold Worn V Packings High Pressure or Lo Pressure Seals Install new seal kit Increase frequency of service Worn adapter o rings Install new o rings Into the crankcase Humid air condensing into water inside the crankcase Install ...

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