Pressure in discharge line and in pump must
be at zero before any maintenance to the
pump takes place. Close up suction line. Disconnect fuses to ensure that the driving motor
does not get switched on accidentally.
Make sure that all parts on the pressure side of
the unit are vented and relled, with pressure
at zero, before starting the pump.
In order to prevent air, or an air/water-mixture
being absorbed and to prevent cavitation oc-
curring, the pump-NPSHR, positive suction
head and water temperature must be kept
under control.
Cavitation and/or compression of gases
lead to uncontrollable pressure kicks which
can ruin pump and unit parts and also be
dangerous to the operator or anyone standing nearby.
Giant plunger pumps are suitable for pumping clean water and other non-aggressive or
abrasive media with a specic weight similar to
water.
Safety Rules
Before pumping other liquids - especially
inammable, explosive and toxic media
Pump operation without safety valve as well
as any excess in the temperature or speed
limits automatically voids the warranty. The
safety valve must be regulated in accordance
with the guidelines for liquid spraying units so
that the admissible operating pressure can
- the pump manufacturer must under all
circumstances be consulted with regard to
the resistance of the pump material. It is
the responsibility of the equipment manufacturer and/or operator to ensure that all
pertinent safety regulations are adhered to.
not be exceeded by more than 10%.
When the pump is in operation, the open
shaft end must be covered up by shaft pro-
tector (21), the driven shaft side and coupling
by a contact protector.
Preventative Maintenance Check-List & Recommended Spare Parts List
Check Daily Weekly 50hrs Every Every Every
500 hrs 1500 hrs 3000 hrs
Oil Level/Quality X
Oil Leaks X
Water Leaks X
Belts, Pulley X
Plumbing X
Recommended Spare Parts
Oil Change (1 Quart) X X
Seal Kit (1 kit/pump) X
(See page 6 for kit lit)
Valve Spare Parts (1 kit/pump)
(See page 6 for kit list)
X
MP4120-SWS/MP4124-SWS PUMP SPECIFICATIONS
U.S. Measurements
Max.
Flow
ModelGPMPSIRPMHP°FinFt-Head
MP4120-SWS8.93625145023.11600.78724.6
MP4124-SWS12.826101450241600.94527.9
Metric Measurements
Max.
Flow
ModelL/minbarRPMkW°CmmmWs
MP4120-SWS33.8250145017.270207.5
MP4124-SWS48.6180145017.970248.5
Consult the factory for special requirements that must be met if the
pump is to operate beyond one or more of the limits specied above.
Horsepower Ratings:
We recommend a 1.15 service factor be specied when selecting an electric motor as the power source.
To compute electric motor horsepower required, use the following formula: HP = (GPM X PSI) / 1450.
The formula to determine the horsepower required for a gas engine is: HP = (GPM X PSI) / 1150.
For the Application of a Hydraulic Motor:
To Determine the Torque of a Hydraulic Motor -- (GPM x PSI x 36.77) / RPM = Torque (in-lbs)
Max. Pres-
sure
Max. Pres-
sure
Max.
Speed
Max.
Speed
Power
Required
Power
Required
Max.
Temperature
Max.
Temperature
Plunger
Diameter
Plunger
Diameter
NPSH Re-
quired
NPSH Re-
quired
Calculating RPM / GPM of Pump:
A pump must be connected to an electric motor or gas or diesel engine with the correct ratio of pulleys
and belts to attain the required speed and GPM. The use of a Variable Frequency Drive (VFD) may also
be used to control the RPM of a properly sized electric motor when variable ows are required.
CAUSE
Worn packing seals
Broken valve spring
Belt slippage
Worn or Damaged nozzle
Fouled discharge valve
Fouled inlet strainer
Worn or Damaged hose
Worn or Plugged relief valve on
pump
Cavitation
Unloader
High humidity
Worn seals
Worn bearings
Cavitation
REMEDY
Replace packing seals
Replace spring
Tighten or Replace belt
Replace nozzle
Clean valve assembly
Clean strainer
Repair/Replace hose
Clean, Reset, and Replace worn
parts
Check suction lines on inlet of
pump for restrictions
Check for proper operation
Reduce oil change interval
Replace seals
Replace bearings, Rell crankcase
oil with recommended lubricant
Check inlet lines for restrictions
and/or proper sizing
Rough/Pulsating
Operation with
Pressure Drop
Pressure Drop at Gun
Excessive Leakage
Worn packing
Inlet restriction
Accumulator pressure
Unloader
Cavitation
Restricted discharge plumbing
Worn plungers
Worn packing/seals
Excessive vacuum
Cracked plungers
Inlet pressure too high
Replace packing
Check system for stoppage, air
leaks, correctly sized inlet plumbing
to pump
Recharge/Replace accumulator
Check for proper operation
Check inlet lines for restrictions
and/or proper size
Wrong Grade of oil
Improper amount of oil in crankcase
Giant oil is recommended
Adjust oil level to proper amount
6
REPAIR INSTRUCTION - MP4120-SWS/MP4124-SWS
Disassembly sequence
1. With a 27mm wrench, re-
move the three discharge
plugs (#48) and three inlet
plugs (#42A) from the
manifold (#43).
2. Inspect the plug o-rings
(#48A and #42B) and
replace as necessary.
47 46 45 44A 44
4. Inspect all parts, especially the seating surface
of the valve plate (#45), and replace as neces-
sary.
3. From the discharge port remove
the spring retainer (#47)
spring (#46) and the valve plate
(#45). Using the valve puller
(Available from Snap-On Tools)
remove the valve seat (#44)
5. Remove the six manifold stud nuts
(#50) with a 19mm wrench. Remove the spring washers (#50A).
Tap the back of the manifold with a
rubber mallet to dislodge and slide
it off the studs (#49). The spacer
(#51) can now be removed by pry-
ing gently outward with a screwdriver through the front of the inlet
port.
6. To remove the inlet valve
assembly, insert a 13mm
socket with extension
through the rear of the
inlet manifold (#43) port
and tap it rmly with a
hammer. This will force
the tension spring (#46A),
valve housing (#52) and
the remainder of the inlet
valve assembly out through
the front of the inlet port.
51 44 44A 45 46A 52
7. Pull the inlet valve assembly apart for inspection. Any resis-
tance may be overcome by placing the valve housing (#52) in
a brass jawed vise and carefully tapping the back of the valve
plate (#45) with a screwdriver. Inspect the valve seats (#44),
spring (#46A), o-ring (#44A) and o-ring (#53A) for wear and
replace them as necessary.
7
REPAIR INSTRUCTION - MP4120-SWS/MP4124-SWS
36 35D 35A 35B 35C
8. From the front of the manifold
(#43), remove the packing assembly (#41A, 41, 40, and 39).
Use a small slide hammer puller
if necessary, or insert a wooden
dowel through the back of the
manifold and tap the assembly
out from the back to the front.
10. Note: The following pro-
cedure is only necessary
if a stud bolt (#49) has
been damaged and must
be replaced. To remove
the manifold studs (#49),
place a stud nut (#50),
lock washer (#50A), and
second nut on each stud.
Tighten the nuts against
each other. Hold the front
nut with one wrench, and
remove the stud bolt by
turning the rear nut counterclockwise with another
wrench. To reassemble,
turn the front stud bolt nut
clockwise.
9. Turn the manifold (#43) over and remove the rear v-sleeve
snap ring (#36) and rear v-sleeve assembly (#35A-35D).
These parts should slide out with little resistance. If neces-
sary, a screwdriver may be used to pry outward. Replace
all rubber parts and inspect the metal parts for wear.
29C 29D 29B
11. Inspect ceramic plunger pipe (29B). Clean any dirt or
grime. If the surface of the pipe is rough, scored or pitted,
replace plunger pipe. To remove the ceramic plunger
pipe, turn the plunger bolt (#29C) counterclockwise with
a 13mm socket. Use a steady torque to prevent ceramic
plunger pipe damage. Loosen and remove the plunger
bolt assembly (#29C and #29D) and replace the seal
washer (#29D).
31
12. Inspect the crankcase oil
seals (#31) for evidence of
leaking. If there is oil on
the crankcase (#1) at the
sight of the oil seals, they
must be replaced. The oil
seals are replaced after
removing the crosshead/
plunger assembly (#25) as
described on page 9.
13. Clean the bolt threads
(#29C), apply locktite,
and remount.
8
14. Torque the ceramic plunger
bolt assembly to 300 inchpounds (34 Nm). If originally removed, reinstall the
stud bolts (#49).
REPAIR INSTRUCTIONS - MP4120-SWS/MP4124-SWS
15. Replace the rear v-sleeve assembly (#35A-35D) and replace the
snap ring (#36).
16. Reinstall the pressure ring (#39), v-sleeve
(#40), support ring (#41), and intermediate
ring (#41A) into each plunger bore. Re-install
the spacer ring (#52A).
39 40 41 41A
17. Reassemble the inlet valve assembly in the reverse order of step #6. Make certain all the compo-
nents are press t together and that the spring retainer (#54) is slightly counter sunk in the valve
housing (#52). Grease the o-ring (#53) and replace it on to the valve housing. Reinstall the entire
inlet valve assembly into the manifold (#43). Replace the tension plugs (#42A) and tighten.
18. Reassemble the discharge valve assembly by placing the valve plate
(#45), spring (#46), and spring retainer (#47) on top of the valve seat
(#44). Press t together. Place the entire discharge assembly into dis-
charge port making certain the assembly is properly seated. Replace
discharge plug (#48) and tighten securely.
19. Again lubricate the plungers (29B) and slide the manifold (#43) gently and evenly over the plungers. Press the manifold rmly into place
against the crankcase (#1). Replace the spring washer (#50A) and
tighten the manifold stud nuts (#50) to 59 ft.-lbs. (80 Nm).
9
REPAIR INSTRUCTIONS - MP4120-SWS/MP4124-SWS
Gear End Disassembly
20. Remove the manifold and plunger assemblies as described earlier. Make sure the oil is drained
from the pump before removing the crankcase cover (#4). Remove all screws (#10). Inspect the
crankcase cover o-ring (#5) for damage and replace it as necessary.
21. Remove the connecting rod screws and washers with a 6mm allen wrench. Remove the back
halves of each connecting rod (#24) . Push the connecting rods down as far as possible into the
crankcase (#1) housing. Note that the connecting rod halves are numbered (or colored) and that
the numbers (or colors) must be matched for reassembly.
22. Remove the crankshaft bearing cover screws (#17) with a 13mm wrench. Remove the key (#23) from
the crankshaft (#22).
23. Remove the bearing cover (#14) and any shims (#20A) if any. Remember to replace shims on the
same side of the crankcase (#1) during the reassembly.
24. Steady the pump rear assembly and, using a rubber mallet, tap the crankshaft (#22) from one side.
The far side bearing race will be removed and the near side race will remain in the crankcase. The
roller bearings (#20) will remain on the crankshaft. When both ends are free, the crankshaft can be
removed by hand.
25. To remove the remaining bearing race, place a dowel against the inside edge of the race and tap it
out with a rubber mallet. This is done only if the race wear surface has been damaged.
26. Inspect the bearing race removed with the crankshaft (#22) and replace if wear surface is damaged.
27. Note: The following procedure is only necessary if the inspection shows evidence of heavy
wear. Inspect the crankshaft (#22) and bearings (#20) for wear. To remove the roller bearings from
the crankshaft, use a three inch push puller with a pulley attachment. To remount the bearings, tap
the bearings down the well-lubricated crankshaft with the Giant Bearing Tool. Be sure that the bearing
is rmly seated.
28. Remove the connecting rod (#24) with the attached crosshead/plunger assembly (#25) from the
crankcase (#1) by pulling it straight out. The oil seals (#31) may now be removed by tapping them
out through the front of the crankcase. Be careful not to damage the snap ring.
29. Inspect the surfaces of the crosshead/plunger assembly (#25) and connecting rods (#24) for heavy
scoring or galling due to poor lubrication. Check for play at the joint between connecting rod crosshead/plunger assembly.
30. To remove the crosshead pin (#28) from the crosshead/plunger assembly (#25), the assembly should
be positioned in such a manner to prevent damage to the crosshead when driving the pin out. The
crosshead pin can be driven out by tapping on the tapered side of the pin.
Reassembly Sequence
Note: Always take time to lubricate all metal and nonmetal parts with a light lm of oil before reassem-
bly. This step will help ensure a proper t, at the same time it will protect the pump non-metal parts
(elastomers) from cutting and scoring.
31. Take the crosshead/plunger rod assembly and insert the connecting rod (#24) into the crosshead/
plunger assembly (#25). Drive the tapered end of the crosshead pin (#28) into the beveled side of
the crosshead and through the connecting rod completing the assembly.
Note: The crosshead pin should not extend beyond either side of the crosshead in order to prevent dam-
age to the crosshead bore of the crankcase.
32. Inspect the crankcase crosshead guides for any possible damage.
33. Replace the connecting rod (#24), crosshead/plunger rod assembly (#25) into the crankcase (#1).
34. If removed previously, replace the far side bearing race into the crankcase. Tap with a rubber mallet
until the edges are ush with the crankcase surface.
35. Remove the old crankshaft seal (#15) from the bearing cover (#14). Lubricate the edges of the new
seal and install using the standard Giant Bearing Tool. Remove the bearing tool and tap around the
perimeter of the seal with a rubber mallet to rmly seat the seal. Position the far bearing cover on the
crankcase (#1) and insert the cover bolts (#17). Tighten the cover evenly to the crankcase, setting the
bearing into position. Torque the cover bolts to 221 in.-lbs. (25 Nm).
10
REPAIR INSTRUCTIONS - MP-4120-SWS/MP4124-SWS
Reassembly Sequence
36. Insert the crankshaft (#22) with the mounted bearings (#20) through the near side of the crankcase
(#1). Make certain that the numbers (or colors) or the crankshaft correspond to the numbers (or colors)
on the connecting rods (#24). Reinstall the near side bearing race by inserting it into the crankcase.
Supporting the crankshaft with one hand, tap the race with a rubber mallet until the edge is ush with
the crankcase.
37. Replace any shims (#20A, 20B) and position the bearing cover (#14) as before. Tighten the bearing
cover bolts (#17) evenly to position the bearing race. Torque the bolts to 125 inch-pounds. Once the
crankshaft reassembly is complete, oil the crankshaft races freely before replacing the connecting rod
(#24) end caps.
38. Reassemble the connecting rods (#24), matching the numbered (or colored) halves. Torque the connecting rod bolts (#24A) to 250 in-lbs. (28 Nm).
39. To replace the oil seal (#31) apply Locktite to the outside edges of the seal and install from the front
of the crankcase (#1). The side of the seal with the spring must face the oil. Make sure that the face
of the seal is ush with the crankcase.
40. Clean the back edge of the crankcase and replace the crankcase cover (#4). be careful not to pinch
the crankcase cover o-ring (#5).
41. Fill the crankcase with 32 uid ounces of Giant oil or the equivalent SAE 80W-90 Industrial Gear oil
and check the oil level with the dip stick (#8). The proper level is center of the two lines. Reinstall the
Giant Industries, Inc. pumps and accessories are warranted by the manufacturer to be free from
defects in workmanship and material as follows:
1. For portable pressure washers and self-service car wash applications, the discharge manifolds are guaranteed for the life of the pump. Our other pump parts,
used in portable pressure washers and in car wash applications, are warranted
for ve years from the date of shipment for all pumps used in NON-SALINE, clean
water applications.
2. One (1) year from the date of shipment for all other Giant industrial and
consumer pumps.
3. Six (6) months from the date of shipment for all rebuilt pumps.
4. Ninety (90) days from the date of shipment for all Giant accessories.
This warranty is limited to repair or replacement of pumps and accessories of which the manufac-
turer’s evaluation shows were defective at the time of shipment by the manufacturer. The following items are NOT covered or will void the warranty:
1. Defects caused by negligence or fault of the buyer or third party.
2. Normal wear and tear to standard wear parts.
3. Use of repair parts other than those manufactured or authorized by Giant.
4. Improper use of the product as a component part.
5. Changes or modications made by the customer or third party.
6. The operation of pumps and or accessories exceeding the specications set forth in the Operations Manuals provided by Giant Industries, Inc.
Liability under this warranty is on all non-wear parts and limited to the replacement or repair of
those products returned freight prepaid to Giant Industries which are deemed to be defective
due to workmanship or failure of material. A Returned Goods Authorization (R.G.A.) number and
completed warranty evaluation form is required prior to the return to Giant Industries of all prod-
ucts under warranty consideration. Call (419)-531-4600 or fax (419)-531-6836 to obtain an R.G.A.
number.
Repair or replacement of defective products as provided is the sole and exclusive remedy pro-
vided hereunder and the MANUFACTURER SHALL NOT BE LIABLE FOR FURTHER LOSS,
DAMAGES, OR EXPENSES, INCLUDING INCIDENTAL AND CONSEQUENTIAL DAMAGES
DIRECTLY OR INDIRECTLY ARISING FROM THE SALE OR USE OF THIS PRODUCT.
THE LIMITED WARRANTY SET FORTH HEREIN IS IN LIEU OF ALL OTHER WARRANTIES OR
REPRESENTATION, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE AND ALL
SUCH WARRANTIES ARE HEREBY DISCLAIMED AND EXCLUDED BY THE MANUFACTURER.