DeVilbiss L10120H2-2 User manual

OWNERS MANUAL FOR
TWO-STAGE
AIR COMPRESSOR
Model No.
L10120H2-2
Model No.
Horsepower
Voltage/Hertz/Phase
Minimum Branch Circuit Requirement
*Fuse Type
Air Tank Capacity
Approximate Cut-in Pressure
Approximate Cut-out Pressure
SCFM @ 175 PSIG
Magnetic Starter
L10120H2-2
10
240/480V/60 HZ/3 PHASE
30 Amp
Time Delay
120 Gal. ASME
140 PSIG
175 PSIG
34.2
Required (Included on Compressor)
MGP-SL10120H-2A Rev. 2 1/24/03
DeVilbiss Air Power Company • 213 Industrial Dr. • Jackson, TN 38301-9615
Specification Chart
*A circuit breaker is preferred. Use only a fuse or circuit breaker that is the same rating as
the branch circuit the air compressor is operated on. If the air compressor is connected to
a circuit protected by fuses, use only time delay fuses. Time delay fuses should be
marked "D" in Canada and "T" in the US.
In the unlikely event you should have a problem with this product or if you are missing any parts, it is not necessary
to return it to the store where you purchased it. Simply call our toll free number and talk with our Service
Representative.
OUR OFFICE HOURS ARE FROM
8:00 a.m. to 6:00 p.m. (CST)
MONDAY THROUGH FRIDAY
CALL TOLL FREE 1-800-888-2468

2—ENG
MGP-SL10120H-2A
TABLE OF CONTENTS
Page Page
CAUTION indicates a potentially hazardous situation which, if not
avoided, may result in minor or moderate injury.
This manual contains information that is important for you to know and understand. This information relates to protecting YOUR
SAFETYandPREVENTING EQUIPMENTPROBLEMS. Tohelpyourecognizethis information, we use the symbols to the right.
Please read the manual and pay attention to these sections.
DANGER indicatesan imminently hazardous situation which, if not
avoided, will result in death or serious injury.
CAUTION used without the safety alert symbol indicates a
potentially hazardous situation which, if not avoided, may result
in property damage.
WARNING indicates a potentially hazardous situation which, if not
avoided, could result in death of serious injury.
Retain Original Sales Receipt as Proof of Purchase for Warranty Repair Work.
SAFETY GUIDELINES - DEFINITIONS
SAFETYGUIDELINES ................................... 2
WARNING CHART......................................... 3-5
SPECIFICATIONS .......................................... 6
GLOSSARY .................................................... 6
DUTY CYCLE ................................................ 6
GENERALINFORMATION ............................ 7
ON-RECEIPTINSPECTION ........................... 7
DESCRIPTION OF OPERATION ................... 8
INSTALLATION AND
BREAK-INPROCEDURES ............................. 9-12
Locationof Air Compressor .......................... 9
AirCompressorAnchoring Methods ............. 9
WiringInstructions and Diagram ................... 10
Voltageand Circuit Protection ...................... 10
AirFilter Installation ...................................... 11
Break-inProcedures..................................... 11
AdditionalRegulators and Controls .............. 11
Lubrication and Oil ....................................... 11
Piping and Diagram ...................................... 12
OPERATINGPROCEDURES ......................... 13
MAINTENANCE ............................................. 14
SERVICEINSTRUCTIONS ............................. 15-16
AirFilter-Inspection andReplacement .......... 15
Oil-CheckingandChanging .......................... 15
Recommended Oils ..................................... 15
Check Valve-Inspection and Replacement ..15-16
Safety Valve-Inspection and Replacement ... 16
Adjusting Belt Tension .................................. 16
Motor Pulley and Flywheel Alignment ........... 17
AdditionalService ........................................ 17
STORAGE....................................................... 17
TROUBLESHOOTINGGUIDE ...................... 18-21
COMPRESSORDIAGRAM ............................ 22
COMPRESSORPARTS LIST ......................... 23
COMPRESSORPUMP DIAGRAM ................ 24
PUMP PARTS LIST ....................................... 25
SERVICENOTES ............................................ 26
WARRANTYSTATEMENT ............................. 27
HOW TO ORDER REPAIR PARTS ....... BackCover

3—ENG MGP-SL10120H-2A
RISK OF BURSTING
IT IS NORMAL FOR ELECTRICAL CONTACTS WITHIN THE
MOTOR AND PRESSURE SWITCH TO SPARK.
IF ELECTRICAL SPARKS FROM COMPRESSOR COME INTO
CONTACT WITH FLAMMABLE VAPORS, THEY MAY IGNITE,
CAUSING FIRE OR EXPLOSION.
RESTRICTING ANY OF THE COMPRESSOR VENTILATION
OPENINGS WILL CAUSE SERIOUS OVERHEATING AND
COULD CAUSE FIRE.
UNATTENDED OPERATION OF THIS PRODUCT COULD
RESULT IN PERSONAL INJURY OR PROPERTY DAMAGE.
ALWAYS OPERATE THE COMPRESSOR IN A WELL VENTI-
LATED AREA FREE OF COMBUSTIBLE MATERIALS,
GASOLINE OR SOLVENT VAPORS.
IF SPRAYING FLAMMABLE MATERIALS, LOCATE COMPRES-
SOR AT LEAST 20 FEET AWAY FROM SPRAY AREA. AN
ADDITIONAL LENGTH OF HOSE MAY BE REQUIRED.
STORE FLAMMABLE MATERIALS IN A SECURE LOCATION
AWAY FROM COMPRESSOR.
NEVER PLACE OBJECTS AGAINST OR ON TOP OF COM-
PRESSOR. OPERATE COMPRESSOR IN AN OPEN AREA AT
LEAST 12 INCHES AWAY FROM ANY WALL OR OBSTRUC-
TION THAT WOULD RESTRICT THE FLOW OF FRESH AIR TO
THE VENTILATION OPENINGS.
OPERATE COMPRESSOR IN A CLEAN, DRY, WELL VENTILATED
AREA. DO NOT OPERATE UNIT INDOORS OR IN ANY CON-
FINED AREA.
ALWAYS REMAIN IN ATTENDANCE WITH THE PRODUCT
WHEN IT IS OPERATING.
SAVE THESE INSTRUCTIONS
IMPROPER OPERATION OR MAINTENANCE OF THIS PRODUCT COULD RESULT IN SERIOUS INJURY AND PROPERTY
DAMAGE. READ AND UNDERSTAND ALL WARNINGS AND OPERATING INSTRUCTIONS BEFORE USING THIS EQUIPMENT.
RISK OF EXPLOSION OR FIRE
AIR TANK: THE FOLLOWING CONDITIONS COULD LEAD TO A WEAKENING OF THE TANK, AND RESULT IN A
VIOLENT TANK EXPLOSION AND COULD CAUSE PROPERTY DAMAGE OR SERIOUS INJURY.
DRAIN TANK DAILY OR AFTER EACH USE. IF TANK DEVEL-
OPS A LEAK, REPLACE IT IMMEDIATELY WITH A NEW TANK OR
REPLACE THE ENTIRE COMPESSOR.
NEVER DRILL INTO, WELD, OR MAKE ANY MODIFICATIONS
TO THE TANK OR ITS ATTACHMENTS.
THE TANK IS DESIGNED TO WITHSTAND SPECIFIC OPERATING
PRESSURES. NEVER MAKE ADJUSTMENTS OR PARTS
SUBSTITUTIONS TO ALTER THE FACTORY SET OPERATING
PRESSURES.
FOR ESSENTIAL CONTROL OF AIR PRESSURE, YOU MUST
INSTALL A PRESSURE REGULATOR AND PRESSURE GAUGE
TO THE AIR OUTLET OF YOUR COMPRESSOR. FOLLOW THE
EQUIPMENT MANUFACTURERS RECOMMENDATION AND
NEVER EXCEED THE MAXIMUM ALLOWABLE PRESSURE
RATING OF ATTACHMENTS. NEVER USE COMPRESSOR TO
INFLATE SMALL LOW-PRESSURE OBJECTS SUCH AS
CHILDREN’S TOYS, FOOTBALLS, BASKETBALLS. ETC.
1. FAILURE TO PROPERLY DRAIN CONDENSED WATER
FROM THE TANK, CAUSING RUST AND THINNING OF THE
STEEL TANK.
2. MODIFICATIONS OR ATTEMPTED REPAIRS TO THE TANK.
3. UNAUTHORIZED MODIFICATIONS TO THE UNLOADER
VALVE, SAFETY VALVE, OR ANY OTHER COMPONENTS
WHICH CONTROL TANK PRESSURE.
4. EXCESSIVE VIBRATION CAN WEAKEN THE AIR TANK
AND CAUSE RUPTURE OR EXPLOSION.
ATTACHMENTS & ACCESSORIES:
EXCEEDING THE PRESSURE RATING OF AIR TOOLS, SPRAY
GUNS, AIR OPERATED ACCESSORIES, TIRES AND OTHER
INFLATABLES CAN CAUSE THEM TO EXPLODE OR FLY
APART, AND COULD RESULT IN SERIOUS INJURY.
HAZARD
WHAT CAN HAPPEN HOW TO PREVENT IT
WHAT CAN HAPPEN HOW TO PREVENT IT
IMPORTANT SAFETY INSTRUCTIONS

4—ENG
MGP-SL10120H-2A
WHAT CAN HAPPEN HOW TO PREVENT IT
RISK FROM FLYING OBJECTS
THE COMPRESSED AIR STREAM CAN CAUSE SOFT TISSUE
DAMAGE TO EXPOSED SKIN AND CAN PROPEL DIRT, CHIPS,
LOOSE PARTICLES AND SMALL OBJECTS AT HIGH SPEED,
RESULTING IN PROPERTY DAMAGE OR PERSONAL INJURY.
ALWAYS WEAR ANSI Z87.1 APPROVED SAFETY GLASSES
WITH SIDE SHIELDS WHEN USING THE COMPRESSOR.
NEVER POINT ANY NOZZLE OR SPRAYER TOWARD ANY
PART OF THE BODY OR AT OTHER PEOPLE OR ANIMALS.
ALWAYS TURN THE COMPRESSOR OFF AND BLEED PRES-
SURE FROM THE AIR HOSE AND TANK BEFORE ATTEMPTING
MAINTENANCE, ATTACHING TOOLS OR ACCESSORIES.
THE COMPRESSED AIR FROM YOUR COMPRESSOR IS NOT
SAFE FOR BREATHING! THE AIR STREAM MAY CONTAIN
CARBON MONOXIDE, TOXIC VAPORS OR SOLID PARTICLES
FROM THE TANK.
SPRAYED MATERIALS SUCH AS PAINT, PAINT SOLVENTS,
PAINT REMOVER, INSECTICIDES, WEED KILLERS, CONTAIN
HARMFUL VAPORS AND POISONS.
ALWAYS OPERATE AIR COMPRESSOR OUTSIDE IN A CLEAN,
WELL VENTILATED AREA. AVOID ENCLOSED AREAS SUCH AS
GARAGES, BASEMENTS, STORAGE SHEDS, WHICH LACK A
STEADY EXCHANGE OF AIR. KEEP CHILDREN, PETS AND
OTHERS AWAY FROM AREA OF OPERATION.
NEVER INHALE AIR FROM THE COMPRESSOR EITHER
DIRECTLY OR FROM A BREATHING DEVICE CONNECTED TO
THE COMPRESSOR.
WORK IN AN AREA WITH GOOD CROSS-VENTILATION. READ
AND FOLLOW THE SAFETY INSTRUCTIONS PROVIDED ON
THE LABEL OR SAFETY DATA SHEETS FOR THE MATERIAL
YOU ARE SPRAYING. USE A NIOSH/MSHA APPROVED
RESPIRATOR DESIGNED FOR USE WITH YOUR SPECIFIC
APPLICATION.
HAZARD
WHAT CAN HAPPEN HOW TO PREVENT IT
RISK TO BREATHING
YOUR AIR COMPRESSOR IS POWERED BY ELECTRICITY.
LIKE ANY OTHER ELECTRICALLY POWERED DEVICE, IF IT IS
NOT USED PROPERLY IT MAY CAUSE ELECTRIC SHOCK.
REPAIRS ATTEMPTED BY UNQUALIFIED PERSONNEL CAN
RESULT IN SERIOUS INJURY OR DEATH BY ELECTROCU-
TION.
ELECTRICAL GROUNDING: FAILURE TO PROVIDE ADEQUATE
GROUNDING TO THIS PRODUCT COULD RESULT IN SERIOUS
INJURY OR DEATH FROM ELECTROCUTION. SEE GROUND-
ING INSTRUCTIONS.
NEVER OPERATE THE COMPRESSOR OUTDOORS WHEN IT IS
RAINING OR IN WET CONDITIONS.
NEVER OPERATE COMPRESSOR WITH COVER COMPONENTS
REMOVED OR DAMAGED.
ANY ELECTRICAL WIRING OR REPAIRS REQUIRED ON THIS
PRODUCT SHOULD BE PERFORMED BY AUTHORIZED
SERVICE CENTER PERSONNEL IN ACCORDANCE WITH
NATIONAL AND LOCAL ELECTRICAL CODES.
MAKE CERTAIN THAT THE ELECTRICAL CIRCUIT TO WHICH
THE COMPRESSOR IS CONNECTED PROVIDES PROPER
ELECTRICAL GROUNDING, CORRECT VOLTAGE AND
ADEQUATE FUSE PROTECTION.
WHAT CAN HAPPEN HOW TO PREVENT IT
RISK OF ELECTRICAL SHOCK

5—ENG MGP-SL10120H-2A
MOVING PARTS SUCH AS THE PULLEY, FLYWHEEL AND BELT
CAN CAUSE SERIOUS INJURY IF THEY COME INTO CONTACT
WITH YOU OR YOUR CLOTHING.
ATTEMPTING TO OPERATE COMPRESSOR WITH DAMAGED
OR MISSING PARTS OR ATTEMPTING TO REPAIR COM-
PRESSOR WITH PROTECTIVE SHROUDS REMOVED CAN
EXPOSE YOU TO MOVING PARTS AND CAN RESULT IN
SERIOUS INJURY.
NEVER OPERATE THE COMPRESSOR WITH GUARDS OR
COVERS WHICH ARE DAMAGED OR REMOVED.
ANY REPAIRS REQUIRED ON THIS PRODUCT SHOULD BE
PERFORMED BY AUTHORIZED SERVICE CENTER PERSON-
NEL.
HAZARD
RISK FROM MOVING PARTS
WHAT CAN HAPPEN HOW TO PREVENT IT
TOUCHING EXPOSED METAL SUCH AS THE COMPRESSOR
HEAD OR OUTLET TUBES, CAN RESULT IN SERIOUS BURNS.
NEVER TOUCH ANY EXPOSED METAL PARTS ON COMPRES-
SOR DURING OR IMMEDIATELY AFTER OPERATION. COM-
PRESSOR WILL REMAIN HOT FOR SEVERAL MINUTES AFTER
OPERATION.
DO NOT REACH AROUND PROTECTIVE SHROUDS OR ATTEMPT
MAINTENANCE UNTIL UNIT HAS BEEN ALLOWED TO COOL.
WHAT CAN HAPPEN HOW TO PREVENT IT
A PORTABLE COMPRESSOR CAN FALL FROM A TABLE,
WORKBENCH OR ROOF CAUSING DAMAGE TO THE COM-
PRESSOR AND COULD RESULT IN SERIOUS INJURY OR
DEATH TO THE OPERATOR.
ALWAYS OPERATE COMPRESSOR IN A STABLE SECURE
POSITION TO PREVENT ACCIDENTAL MOVEMENT OF THE
UNIT. NEVER OPERATE COMPRESSOR ON A ROOF OR
OTHER ELEVATED POSITION. USE ADDITIONAL AIR HOSE
TO REACH HIGH LOCATIONS.
WHAT CAN HAPPEN HOW TO PREVENT IT
OIL CAN LEAK OR SPILL AND COULD RESULT IN FIRE OR
BREATHING HAZARD, SERIOUS INJURY OR DEATH CAN RESULT.
OIL LEAKS WILL DAMAGE CARPET, PAINT OR OTHER SURFACES
IN VEHICLES OR TRAILERS.
WHAT CAN HAPPEN HOW TO PREVENT IT
ALWAYS PLACE COMPRESSOR ON A PROTECTIVE MAT WHEN
TRANSPORTING TO PROTECT AGAINST DAMAGE TO VEHICLE
FROM LEAKS. REMOVE COMPRESSOR FROM VEHICLE IMMEDI-
ATELY UPON ARRIVAL AT YOUR DESTINATION.
RISK OF PROPERTY DAMAGE WHEN TRANSPORTING
COMPRESSOR
(Fire, Inhalation, Damage to Vehicle Surfaces)
RISK OF BURNS
ESW-99 — 9/26/99ESW-99 — 9/26/99
ESW-99 — 9/26/99ESW-99 — 9/26/99
ESW-99 — 9/26/99
RISK OF FALLING

6—ENG
MGP-SL10120H-2A
Refertocoverpageforthespecificationsofyourcompressor.Useonlyafuseorcircuitbreakerthatisthesamerating
asthebranchcircuittheaircompressorisoperatedon.Ifthecompressorisconnectedtoacircuitprotectedbyfuses,
use dual element time delay fuses, as noted in specification chart.
SPECIFICATIONS
GLOSSARY
CFM:CFM:
CFM:CFM:
CFM: Cubic feet per minute.
SCFM:SCFM:
SCFM:SCFM:
SCFM: Standard cubic feet per minute; a unit of
measure of air delivery.
PSIG:PSIG:
PSIG:PSIG:
PSIG: Poundspersquareinchgauge; a unit of measure
of pressure.
ASME:ASME:
ASME:ASME:
ASME: American Society of Mechanical Engineers;
made, tested, inspected and registered to meet the
standards of the ASME.
California CodeCalifornia Code
California CodeCalifornia Code
California Code:Unit may comply with California
Code462 (l)(2)/(M) (2). Specification/ModelLabel is on
the side of the tank on units that comply with California
Code.
Cut-In Pressure:Cut-In Pressure:
Cut-In Pressure:Cut-In Pressure:
Cut-In Pressure: While the motor is off, air tank
pressuredrops asyou continue touse youraccessory.
When the tank pressure drops to a certain low level the
motor will restart automatically. The low pressure at
which the motor automatically re-starts is called “cut-
in pressure.”
Cut-Out Pressure:Cut-Out Pressure:
Cut-Out Pressure:Cut-Out Pressure:
Cut-Out Pressure: When you turn on your air com-
pressor and it begins to run, air pressure in the air tank
begins to build. It builds to a certain high pressure
before the motor automatically shuts off - protecting
yourairtank from pressurehigher thanits capacity. The
highpressureatwhich the motor shutsoff iscalled "cut-
out pressure."
To Lock Out Power:To Lock Out Power:
To Lock Out Power:To Lock Out Power:
To Lock Out Power: Place a lock on the line power
switch so no one else can turn on the power.
DUTY CYCLE
All DeVilbiss Air Power manufactured air compressors
shouldbe operated onnotmore than a50% duty cycle.
This means an air compressor that pumps more than
50%of one hour,isconsidered misuse, becausethe air
compressor is undersized for the required air demand.
Maximum compressor pumping time per hour is 30
minutes.
Improper electrical installation of this product
may void its warranty and your fire insurance.
Have circuit wiring performed by qualified per-
sonnel such as a licensed electrician who is
familiar with the current national electric code
and any prevailing local electrical codes.

7—ENG MGP-SL10120H-2A
GENERAL INFORMATION
You have purchased a complete compressor outfit con-
sisting of an air compressor, air tank, electric motor, and
associatedcontrols and instruments.The outfit youhave
selected is a stationary model and contains a two stage
air compressor pump.
Your new compressor outfit can be used for operating
paintsprayers, airtools, grease guns,air brushes,caulk-
ing guns, sandblasters, inflating tires, etc.
An air pressure regulator is usually necessary for most
applications. An air line filter is normally required for
removalofmoisture and oil vaporin compressedair when
a paint spray gun is used.
Anin-linelubricatorisoftenrequiredforairtoolstoprolong
tool life.
Separateairtransformerswhichcombinethe functions of
air regulation and/or moisture and dirt removal should
be used where applicable.
A regularly scheduled program of preventive mainte-
nance will help provide the long life that has been
designed into your compressor outfit. Before operating
orperforming any maintenance on your compressor, refer
tothismanual. To keep yourcompressor ingood working
order, refer to these publications often and perform
preventive maintenance steps as recommended.
ON-RECEIPT INSPECTION
Each air compressor outfit is carefully checked before
shipment.With improperhandling, damage may result in
transit and cause problems in compressor operation.
Immediately upon arrival, check equipment for both
concealedand visible damagestoavoid expenses being
incurred to correct such problems. This should be done
regardlessof anyvisible signs ofdamage to theshipping
container.Report any damagestocarrier and arrangefor
inspection of goods immediately.
For the location or a listing of the nearest DeVilbiss Air
Power Authorized Warranty Service Center, call our toll
freenumber at 1-800-888-2468.

8—ENG
MGP-SL10120H-2A
DESCRIPTION OF OPERATION
to restart freely. When the motor stops running, air will
beheardescaping from thevalve forafewseconds. No
air should be heard leaking when the motor is running.
Pressure Switch:Pressure Switch:
Pressure Switch:Pressure Switch:
Pressure Switch: The pressure switch automatically
startsthemotor when the airtank pressuredrops below
the factory set "cut-in" pressure. It stops the motor
whenthe air tankpressurereaches the factoryset"cut-
out"pressure.
Shut-off Valve:Shut-off Valve:
Shut-off Valve:Shut-off Valve:
Shut-off Valve: Turn the knob counterclockwise to
open the valve and clockwise to close.
Air Tank Safety Valve:Air Tank Safety Valve:
Air Tank Safety Valve:Air Tank Safety Valve:
Air Tank Safety Valve: Ifthepressureswitchdoesnot
shut off the air compressor at its cut-out pressure
setting, the safety valve will protect against high pres-
sureby "popping off"atits factory setpressure (slightly
higher than the pressure switch cut-out setting).
Aftercooler Safety Valve:Aftercooler Safety Valve:
Aftercooler Safety Valve:Aftercooler Safety Valve:
Aftercooler Safety Valve: On two stagecompressor
units,safety valve isprovidedto prevent over-pressuri-
zation of the aftercooler. The valve will protect the
aftercooler by "popping off" at its factory set pressure.
Regulator:Regulator:
Regulator:Regulator:
Regulator: An air pressure regulator or a separate air
transformerwhichcombines the functions ofairregula-
tionand/or moistureand dirt removalis recommended
formost applications.
Tank Pressure Gauge:Tank Pressure Gauge:
Tank Pressure Gauge:Tank Pressure Gauge:
Tank Pressure Gauge: The tank pressure gauge
indicatesthe reserveairpressure inthe tank. Onoutfits
with no pressure regulator, this is also the pressure
available at the air outlet.
Drain Valve:Drain Valve:
Drain Valve:Drain Valve:
Drain Valve: At the base of the air tank to drain
condensation at the end of each use.
ON/AUTO-OFF Switch:ON/AUTO-OFF Switch:
ON/AUTO-OFF Switch:ON/AUTO-OFF Switch:
ON/AUTO-OFF Switch: Turn this switch ON to
provideautomatic powertothepressureswitch andOFF
toremove power.
Air Intake Filter:Air Intake Filter:
Air Intake Filter:Air Intake Filter:
Air Intake Filter: This filter is designed to clean air
coming into the pump. This filter must always be clean
and ventilation openings free from obstructions. See
"Maintenance".
Air Compressor Pump:Air Compressor Pump:
Air Compressor Pump:Air Compressor Pump:
Air Compressor Pump: Intwo stage compressors,air
is first compressed to an intermediate pressure in the
large bore cylinder, and after passing through an inter-
cooler,theairisfurthercompressedtoahigherpressure
inthesmallerborecylinder. This process continuesuntil
the air tank pressure reaches the factory set cutoff
pressure. At that point the pressure switch shuts the
electric motor off.
Check Valve:Check Valve:
Check Valve:Check Valve:
Check Valve: When the air compressor is operating,
the check valve is "open", allowing compressed air to
enter the air tank. When the air compressor reaches
"cut-out" pressure, the check valve "closes", allowing
air pressure to remain inside the air tank.
Pressure Release Valve:Pressure Release Valve:
Pressure Release Valve:Pressure Release Valve:
Pressure Release Valve: The pressure releasevalve
located on the side of the pressure switch, is designed
toautomatically releasecompressedair fromthecom-
pressorhead and theoutlet tubewhenthe air compres-
sor reaches "cut-out" pressure or is shut off. If the air
is not released, the motor will try to start, but will be
unable to. The pressure release valve allows the motor

9—ENG MGP-SL10120H-2A
INSTALLATION AND BREAK-IN PROCEDURES
This compressor should be permanently mounted in
place on a level floor. Operate the air compressor in a
clean, dry and well ventilated area. The air intake filter
mustbekeptclearofobstructions whichcouldreduceair
delivery of the air compressor. The air compressor
should be located at least 12" away from walls or other
obstructions that could interfere with the flow of air
through the fan bladed flywheel. The air compressor
crankcase and head are designed with fins to provide
propercooling.
The flywheel side of the outfit should be placed toward
thewallandprotectedwithatotallyenclosedbelt guard.
In no case should the flywheel be closer than 12 to 18
inchesfrom thewallorotherobstructionthat willinterfere
with the flow of air through the fan bladed flywheel. The
area should allow space on all sides for air circulation
and for ease of normal maintenance. Keep the outfit
awayfromareaswhichhavedirt,vaporandvolatilefumes
in the atmosphere which may clog and gum the intake
filterand valves,causinginefficientoperation.Wherethis
is not practical a remote air intake is recommended.
If humidity is high, an air filter can be installed to
remove excessive moisture. Closely follow instruc-
tions packaged with the filter for proper installation. It
must be installed as close as possible to the acces-
sory.
The air compressor should be as near to air outlets as
possible in order to avoid long pipe lines. Do not place
the air compressor where heat is excessive.
Air Compressor Anchoring
Methods
THE PUMP ASSEMBLY DOES NOT PRO-
VIDEADEQUATE STABILITY ORSUPPORT
FOR LIFTING THE UNIT. IF THE OUTFIT
MUST BE MOVED, USE THE TANK FOR
LIFTING.
VIBRATION CAN WEAKEN THE AIR TANK
AND CAUSE AN EXPLOSION. THE COM-
PRESSORMUST BE PROPERLY MOUNTED
AS ILLUSTRATED BELOW.
Anchoring of Horizontal Unit
Horizontal Units
Horizontal air compressors must be bolted to the floor.
Bolting holes are provided in the base feet. Mount the
air compressor on a solid, level foundation. Support
compressor weight evenly on all four feet. Solid shims
may be used if necessary.
ISOLATOR
WASHER
(supplied)
Location of the Air Compressor
Note
Where a remote air intake is used, en-
large the size of the air intake piping by
one pipe size for each 10 feet of length.
FLAT WASHER
LAG SCREW
(NOT SUPPLIED)
TORQUE TO
5 TO 10 FT-LB

10—ENG
MGP-SL10120H-2A
INSTALLATION AND BREAK-IN PROCEDURES
Wiring Instructions
Ifyour compressor unitis not equippedwith a plug-intype
power cord, perform electrical wiring according to the
followinginstructions:
IMPROPER ELECTRICAL GROUNDING CAN
RESULT IN A RISK OF ELECTRICAL SHOCK.
WIRING SHOULD BE DONE BY A LICENSED
ELECTRICIAN IN ACCORDANCE WITH NA-
TIONAL AND LOCAL CODES AND ORDI-
NANCES.
2.The supply line has the same electrical characteristics
(voltage, cycle, and phase) as motor.
Wiring must be such that full motor nameplate voltage
plus or minus 10%, is available at the motor terminals
during starting. Refer to local codes for recommended
wire sizes for correct wire size and maximum wire run;
undersize wire causes high amp draw and overheating to
the motor.
Install the compressor outfit as close to the main power
supply as possible. This practice will avoid using long
lengthsof electrical wiringfor thepowersupply whichcan
cause power loss to the motor. When connecting wires
make sure that:
1.The amperage rating of the electrical box is adequate.
Refer to the Specification Chart (cover page) for your
air compressor outfit.
Electrical wiring must be located away
fromhotsurfacessuch as the compressor
head, compressor cylinder, or compres-
sor outlet tube.
Voltage and Circuit Protection
Referto The SpecificationChart for thevoltage and circuit
protection requirements of your compressor. Use only a
fuseor circuit breakerthat is thesamerating as thebranch
circuittheaircompressoris operated on. If thecompressor
is connected to a circuit protected by fuses, use only dual
element time delay fuses. See Specification Chart.
IF REQUIREDIF REQUIRED
IF REQUIREDIF REQUIRED
IF REQUIRED
NOTE: THESE OUTFITS DO NOT INCLUDE ANY
WIRING BECAUSE OF VARIOUS
INSTALLATION REQUIREMENTS.
Wiring of Compressor Units
Typical schematic subject to all changes as dictated by
local electrical codes and authorities.
Typical Wiring of Compressor Units
With more than 80 Gallons Capacity

11—ENG MGP-SL10120H-2A
INSTALLATION AND BREAK-IN PROCEDURES
Break-In Procedures Additional Regulators and
Controls
Multi-viscositymotoroilslike10W30,should
not be used in an air compressor. They
leave carbon deposits on critical compo-
nents,thusreducingperformance and com-
pressor life. Use air compressor oil only.
SeeMaintenancefor oil recommendations.
The Break-In Procedure is required when:
A. New compressor is put into service.
B. Check valve is replaced
C. New pump is installed on tank.
1.Recheck compressor wiring. Make sure wires are
secureat all terminalconnections. Free allcontactsof
loose wire cuttings, etc.
2.Open the air outlet valve fully to permit air to escape
andpreventairpressurebuild-up in the tankduring the
break-inperiod.
3.Position the fuse disconnect or circuit breaker to the
ONposition and, ifequipped,turn theON/AUTO-OFF
switch on the pressure switch to the ON position.
4.Run thecompressor for 30minutes. Make surethe air
outlet, or globe valve, is open and there is no tank
pressurebuild-up.
5.Check for excessive vibration and noise. Adjust air
compressor belt guard as necessary to eliminate
chatter. Re-adjust or shim the air compressor feet, if
necessary, for proper level.
6.Close theoutlet valve andletair compressor pumpup
to"cut-out pressure". Turnthe air compressoroffand
check oil level. Add oil if necessary. Connect air hose
to air outlet adapter.
7.Checkall air line fittingsandconnections/piping for air
leaks by applying a soap solution. Correct as neces-
sary. Even minor leaks can cause this air compressor
to overwork, resulting in premature breakdown or
inadequateperformance.
Serious damage may result if the fol-
lowing break-in instructions are not
closely followed.
Since the air tank pressure is usually greater than that
whichis needed, aseparate regulator isusually employed
tocontrolthe air pressure aheadof anyindividual air driven
device.
Separateairtransformers that combine thefunctions ofair
regulation and moisture and dirt removal should be used
whereapplicable.
Lubrication and Oil
Remove the oil fill plug and fill the crankcase with recom-
mendedoil.Referto the Service Instructionsin thismanual
forthe specific oilrecommended for usein your compres-
sor unit. Replace the oil fill plug. Always fill to middle of
sight glass.
Compressors are shipped without oil. A
small amount of oil may be present in the
pump upon receipt of the air compressor.
This is due to plant testing and does not
mean that the pump contains oil. Do not
attempt to operate in order to check wiring
or for any reason without first adding oil to
thecrankcase.Seriousdamage to the pump
can result from even very limited use with-
out oil. Fill crankcase with recommended
oil before operating.
Air Filter Installation
To install air filter:
Insert threaded end of the air filter assembly into elbow
and tighten until snug.
Do not operate compressor without air
filter assembly installed as this will
cause damage to the compressor.

12—ENG
MGP-SL10120H-2A
INSTALLATION AND BREAK-IN PROCEDURES
Piping NoteNote
NoteNote
Note
For underground installation, bury air
lines below the frost line and avoid
pockets where condensation can gather
and freeze. Apply pressure before un-
derground lines are covered to make
sure all pipe joints are free from leaks.
Plastic or PVC pipe is not designed for use
with compressed air. Regardless of its indi-
cated pressure rating, plastic pipe can burst
from air pressure. Use only metal pipe for
air distribution lines.
NoteNote
NoteNote
Note
Where a remote air intake is used, en-
large the size of the air intake piping by
one pipe size for each 10 feet of length.
A typical compressed air distribution system as shown
below should be of sufficient pipe size to keep the
pressure drop between the supply and point of use to a
minimum. All pipes and fittings used must be certified
safeforthepressuresinvolved.Pipethreadsealant must
be used on all threads, and all joints are to be made up
tight, since small leaks in the piping system are the
largest single cause of high operating costs.
All piping should be sloped to an accessible drain point
and all outlets should be taken from the top of the main
distribution air line so that moisture cannot enter the
outlet.
Themaindistributionair lineshouldnotbesmaller than
thecompressorairdischargevalveoutlet.Asmallerline
will restrict the flow of air. If piping is over 100 feet long,
or if required air flow will exceed 15 SCFM, use 3/4"
piping.
It is recommended that a flexible coupling be installed
between the air discharge valve outlet and main air
distributionlinetoallowforvibration.
To remove dirt, oil and water, install a separator in the
maindistributionline.Installseparatoraminimumof5to
6 feet from compressor to allow the air to cool to room
temperaturebeforepassingthroughtheseparator.Addi-
tionalseparatorsorfiltersmaybeuseddependingonthe
application.
Liquid water occurs naturally in air lines as a result of
compression. Moisture vapor in ambient air is concen-
tratedwhenpressurizedandcondenseswhencooledin
downstream air piping. Compressed air dryers reduce
the water vapor concentration and prevent liquid water
formation in compressed air lines. Dryers are a neces-
sary companion to filters, aftercoolers, and automatic
drains for improving the productivity of compressed air
systems.
Waterandwatervaporremovalincreasestheefficiency
of air operated equipment, reduces contamination and
rusting, increases the service life of pneumatic equip-
mentandtools,preventsairlinefreeze-ups,andreduces
productrejects.Theuseofdryersandfiltersarerecom-
mended when these moisture related problems are
reportedtoourfactoryordistributorservicedepartment.

13—ENG MGP-SL10120H-2A
OPERATING PROCEDURES
1. Before attachingan air hoseor accessory, makesure the
outlet valve is in the closed position. On units equipped
withapressureswitchlevermakesuretheswitch is in the
OFF position.
Compressed air from the outfit may contain
water condensation and oil mist. Do not spray
unfiltered air at an item that could be dam-
aged by moisture or oil mist. Some air oper-
ated tools or devices may require filtered air.
Read instructions for air tool or device.
2.Attach regulator, hose and accessory. On models
without an air pressure regulator, one must be installed
before using accessories.
TOO MUCH AIR PRESSURE CAUSES A HAZ-
ARDOUS RISK OF BURSTING. CHECK THE
MANUFACTURER'S MAXIMUM PRESSURE
RATINGFORAIR TOOLS AND ACCESSORIES.
THEREGULATOR OUTLET PRESSUREMUST
NEVER EXCEED THE MAXIMUM PRESSURE
RATING.
3.Turnthe compressor on and allow tank pressure tobuild.
Onunitsequippedwithapressureswitch lever, place the
switch in the ON-AUTO position. The motor will stop
whentank pressure reaches"cut-out pressure".
4.Open theoutlet valve.
When You Are Finished:
6. Turn the compressor unit off.
7. Turntheregulatorcounterclockwise and set the outlet
pressure to zero.
8. Remove the air tool or accessory.
9. Open the regulator and allow the air to slowly bleed
fromthetank. Close theregulator whentank pressure
is approximately 20 psi.
10. Open the drain cock valve underneath the tank and
drainwaterfromairtank.Collectthewaterinasuitable
containter.Continueoperatingunit until all moisture is
removed from the air tank.
11. Afterthewaterhasbeendrained,close the drain cock.
- if the compressor is under continuous use - drain at
least once each day.
- if the compressor is only used occasionally - drain
after each use.
Note
If drain cock valve is clogged, release air pres-
sure in air tank. The drain cock valve can then
be removed, cleaned and reinstalled.
DRAINTANK DAILY.WATERWILLCONDENSE
IN THE AIR TANK. IF NOT DRAINED, THE WA-
TER WILL CORRODE AND WEAKEN THE AIR
TANK, CAUSING A RISK OF AIR TANK RUP-
TURE.THEAIRTANKMUSTBEDRAINEDPROP-
ERLY.
5.Ifanair pressure regulator is inuse, open theregulator by
turning it clockwise. Adjust the regulator to the correct
pressure setting. Your outfit is ready for use.

14—ENG
MGP-SL10120H-2A
MAINTENANCE
UNIT CYCLES AUTOMATICALLY WHEN POWER IS ON. DURING MAINTENANCE, YOU COULD BE
EXPOSED TO VOLTAGE SOURCES, COMPRESSED AIR OR MOVING PARTS. PERSONAL INJURIES
CAN OCCUR. DISCONNECT POWER SOURCE AND BLEED OFF ALL AIR TANK PRESSURE BEFORE
DOING ANY MAINTENANCE OR REPAIR. NEVER OPERATE THE UNIT WITH THE BELT GUARD
REMOVED.
To ensure efficient operation and longer life of the air compressor outfit, a routine maintenance schedule should be
preparedand followed. The following routinemaintenancescheduleisgearedtoanoutfitina normal working environment
operating on a daily basis. If necessary, the schedule should be modified to suit the conditions under which your
compressoris used.Themodificationswilldepend uponthehoursofoperation andtheworkingenvironment.Compressor
outfits in an extremely dirty and/or hostile environment will require a greater frequency of all maintenance checks.
A clean air compressor runs cooler and provides longer service. Clean or blow off fins and any other parts of the air
compressorthatcollect dust or dirt.Do notplace rags,containers orother material onor againstthe ventilationopenings
in the belt guard. Adequate ventilation is necessary to maintain proper air compressor operating temperature.
Routine Maintenance Schedule
Every 160 Hours of Operation
1. Check drive belt tension; adjust if necessary. (Refer
to Service Instructions in this manual.)
2. Inspect air lines and fittings for leaks; correct as
necessary.
3. Check the alignment of the motor pulley to the fly
wheel. If necessary, align to within 1/32 inch on
centerline.
Every 300 Hours of Operation
1. Drain and refill compressor crankcase with clean
oil. Refer to Service Instructions for recommended
oils.
2. Increase frequency of oil changes if humidity or
operating conditions are extreme.
Each Year of Operation (2000 Hours or if a
Problem is Suspected)
Check condition of air compressor pump intake and
exhaust valves. Replace if damaged or worn out.
Every 8 Hours of Operation
1. Check oil level. Add if necessary.
2. Drain water from the air tank, any moisture
separators or transformers.
3. Check for any unusual noise and/or vibration.
4. Manually check all safety valves to make sure they
are operating properly.
5. Inspect for oil leaks and repair any leaks found.
6. Clean and inspect the air intake filter; replace if
necessary.
First 100 Hours of Operation
1. Drain and refill compressor crankcase with clean
oil. Refer to Service Instructions for recommended
oils.
2. Increase frequency of oil changes if humidity or
operating conditions are extreme.
Every 40 Hours of Operation
1. Inspect condition of drive belt; replace if
necessary.
Overfilling with oil will cause premature
compressor failure. Do not overfill.

15—ENG MGP-SL10120H-2A
SERVICE INSTRUCTIONS
A dirty air filter will not allow the compressor to operate
at full capacity. Before you use the compressor, check
the air filter to be sure it is clean. If it is dirty, replace it
with a new filter.
Air Filter - Inspection and
Replacement
NOTENOTE
NOTENOTE
NOTE
Keep the air filter clean at all times. Do
not operate the compressor with the air
filter removed.
1. Check oil level in compressor crankcase before
each use. The oil level should be to the middle of
the oil sight glass.
2. Replace the oil after initial 100 hours of operation
- thereafter, every 300 hours of operation.
3. Remove the oil fill and drain plugs. Collect the oil
in a suitable container.
4. Replace the oil drain plug and refill the crankcase
withrecommended oil.Always fill tomiddle of sight
glass.
Overfilling with oil will cause premature
compressor failure. Do not overfill.
Oil - Checking and Changing
5. Replace the oil fill plug.
6. Start the compressor outfit and run for several
minutes.Shut thecompressordown andcheck the
oil level. If necessary, add more oil.
NoteNote
NoteNote
Note
It is important to maintain the proper oil
level. A low oil level reduces proper cylin-
der wall lubrication and increases ring
wear.
Oil Chart
Cold Climates - 10º F
Moderate Climates -
30º to 80º F
Hot Climates - 80º F
Type
Reciprocating
Non-detergent
petroleum based
compressor rated or
better oil
Oil
Weight
20 Wt.
30 Wt.
40 Wt.
Room or Ambient
Temperature
Acompressorgradenon-detergentoil should be used.
Mostautomotivedetergentoilscauseexcessivecarbon
buildupandshouldnotbeused.Pleasenotethatallunits
run at a constant speed (not start and stop) and should
belubricated byRarus 847, Shellturbo 100, or Anderol
syntheticcompressoroil.Donotuse synthetic oil for the
first 300 hours. All units should be broken in on petro-
leum based oil.
Remove and inspect the check valve at least once a
year or more often if the compressor is heavily used.
Moistureand other contaminants in the hot compressed
air will cause an accumulation of a carbon-like residue
on the working parts. If the valve has heavy carbon
build-up,itshouldbereplaced.Usethefollowingproce-
dure to inspect, clean or replace the check valve.
1. Turn compressor off and disconnect or lock out
powersource.
2. Release air pressure from the air tank.
3. Loosenthetopandbottomtubenutsandremovethe
outlettube.
4. Loosenpressurereleasetubenuts,disconnectfrom
check valve and move tube aside.
5. Unscrew the check valve with a wrench.
Check Valve - Inspection and
Replacement

16—ENG
MGP-SL10120H-2A
Adjusting Belt Tension
Adjust belt tension as described below.
For compressors with a motor slide mount, adjust belt
tension as follows:
1. Slide motor away from compressor until desired
tension is obtained.
On two stage compressors, the belt should deflect
1/2"at midway betweenthe pulley andthe flywheel.
2. Tighten two outside cap screws enough to hold the
motor in place for checking pulley and flywheel
alignment.
3. Tighten all four mounting screws to 20-25 ft.-lbs.
SERVICE INSTRUCTIONS
6. Check that the valve disc moves freely and that the
spring holds the disc in the upper, closed position.
The check valve may be cleaned with a solvent.
7. Apply sealant to the check valve threads. Reinstall
the check valve. Do not overtighten.
8. Replace the outlet tube and tighten top and bottom
nuts. Do not overtighten.
9. Replacethe pressure releasetube and tightennuts.
Donot overtighten.
Safety Valve - Inspection and
Replacement
IF THE SAFETY VALVE DOES NOT WORK
PROPERLY,OVER-PRESSURIZATIONMAY
OCCUR,CAUSINGAIR TANK RUPTUREOR
EXPLOSION. OCCASIONALLY PULL THE
RING ON THE SAFETY VALVE TO MAKE
SURE THAT THE SAFETY VALVE OPER-
ATES FREELY. IF THE VALVE IS STUCK OR
DOESNOTOPERATESMOOTHLY, IT MUST
BEREPLACED WITHAVALVE HAVINGTHE
SAMEPRESSURE RATING.
The safety valve is set at the factory to a pressure
approximately15pounds higher thanthe ratedpressure
oftheoutfit.Ifthepressureswitchmalfunctions and does
not shut off the motor automatically at maximum tank
pressure,the safety valve willprotectthe air tankagainst
excessive air pressure by popping off at its preset
pressure.
SERIOUSINJURYORDAMAGEMAYOCCUR
IF PARTS OF THE BODY OR LOOSE ITEMS
GET CAUGHT IN MOVING PARTS. NEVER
OPERATE THE OUTFIT WITH THE BELT
GUARD REMOVED. THE BELT GUARD
SHOULD BE REMOVED ONLY WHEN THE
COMPRESSORPOWERISDISCONNECTED.

17—ENG MGP-SL10120H-2A
SERVICE INSTRUCTIONS
Motor Pulley and Flywheel
Alignment
1. Remove outer beltguard - To remove, loosen and
removebeltguard screwslocatedat topofbeltguard.
Insert a flat bladed screwdriver and pry beltguard
apart.
2. Place a straight edge along the outside face of the
compressor flywheel to check alignment of V-belt
grooves. (See figure below for proper alignment.)
3. If the belt grooves aren't aligned, continue with step
4 of this procedure. If the belt grooves are aligned,
continue with step 6 of this procedure.
4. Loosen pulley set screw and adjust pulley until it is in
properalignment.
5. Tighten pulley set screw to 145-165 in.-lbs.
6. Reinstall belt guard.
Additional Service
Disassembly or service of the air compressor beyond
what is covered in this manual is not recommended.
If additional service is required, contact your nearest
AuthorizedWarranty Service Center.
STORAGE OF COMPRESSOR OUTFIT
1. Review the Maintenance section on the preceding
pages and perform scheduled maintenance as
necessary. Drain the water from the air tank.
2. Turn compressor off and disconnect or lock out
powersource.
3. Remove any air tool or accessory.
4. Protect the electrical cord and/or air hose from
damage (such as being stepped on or run over).
5. Store the compressor in a clean and dry location.

18—ENG
MGP-SL10120H-2A
CAUSE CORRECTION
PROBLEM
TROUBLESHOOTING GUIDE
PERFORMINGREPAIRS MAYEXPOSE VOLTAGE SOURCES,MOVING PARTS ORCOMPRESSED AIR
SOURCES. PERSONALINJURY MAY OCCUR. PRIORTOATTEMPTING ANY REPAIRS,DISCONNECT
POWER SOURCE FROM THE COMPRESSOR AND BLEED OFF ALL TANK AIR PRESSURE.
Excessivetank pressure - safety
valve pops off (units with ON-
AUTO switch).
Pressure switch "cut-out" too high. ContactService Center tocheck and adjust, orreplace
switch.
Pressure switch does not shut off mo-
torwhen compressorreaches “cut-out"
pressure.
Move the pressure switch lever to the "OFF" position.
Ifthe outfit doesn’t shut off, andthe electrical contacts
are welded together, replace the pressure switch.
See "Wiring of Compressor Units".
Excessivetank pressure -safety
valve pops off (units without
ON-AUTO switch).
Pressure switch does not shut off mo-
torwhen compressor reaches "cut-out
pressure".
Incorrect wiring connections.
Pressure switch must be replaced.
See "Wiring of Compressor Units".
Continuous air relieving from
pressure switch release valve
after shut off.
Operate safety valves manually by pulling on ring. If a
valve still leaks, it should be replaced.
Air leak from safety valves. Possible defect in safety valves.
There is no oil in the compressor.
Squealing sound. Loose belt. Adjust belt tension. (See Belt Replacement.)
Add oil. (See Oil-Checking and Changing)
Air leaks at fittings or hose. Tube fittings are not tight enough. Tighten fittings where air can be heard escaping.
Check fittings with soapy water solution. DO NOT
OVER-TIGHTEN.
Airleaks ator insidecheck valve. Defective or dirty check valve. Adefective check valve results in a constant air leak at
thepressure releasevalve when thereis pressure inthe
tankand thecompressor isshut off. Removeandclean
or replace check valve. DO NOT OVER-TIGHTEN.
Air leaks at pressure switch re-
lease valve during running.
Defectivepressureswitch releasevalve. Remove and replace the release valve.
Defectivecheck valve. See "Air Leak at Check Valve."
Air leaks in air tank or at air tank
welds. Air tank must be replaced.
DO NOT DRILL INTO, WELD, OR OTHERWISE
MODIFY AIR TANK. IT WILL WEAKEN. THE
TANK CAN RUPTURE OR EXPLODE.
Incorrect wiring connections.
Defective air tank.

19—ENG MGP-SL10120H-2A
CORRECTION
CAUSEPROBLEM
TROUBLESHOOTING GUIDE
Motor will not run. Motor overload protection switch has
tripped.
Let motor cool off for 10-15 minutes and overload
protection switch will reset automatically. If the over-
load still trips, check for defective capacitor.
Tankpressure exceedspressure switch
"cut-in pressure".
Motor will start automatically when tank pressure
drops below "cut-in pressure" of pressure switch.
Removeandcleanor replace.DONOTOVERTIGHTEN.
Check valve stuck open.
Loose electrical connections. Check wiring connection inside pressure switch and
motor terminal box area.
Possible defective capacitor. ContactService Center for inspection or replacement
if necessary.
Paint spray on internal motor parts. Have checked by Service Center. Do not operate the
compressor in the spray area. See Flammable Vapor
Warning.
Possible defective motor. Have checked by a local Service Center.
Fuse blown, circuit breaker tripped. 1. Check fuse box for blown fuse and replace if
necessary.Reset circuit breaker.Do not usea fuse
or circuit breaker with higher rating than that
specified for your particular branch circuit.
2. Check for proper fuse; only dual element time
delay fuses are acceptable. Use onlytimedelay
fuses. Time delay fuses should be marked
"D" in Canada and "T" in the US.
3. Check for low voltage conditions.
4. Remove check valve and clean or replace if it is
stuck open or closed.
5. Disconnect the other electrical appliances from
circuit or operate the compressor on its own
branch circuit.
Pressure release valve on pressure
switch has not unloaded head pres-
sure.
On an on/auto pressure switch equipped with a pres-
surerelief valve, bleed thelineby pushing the pressure
switch to the OFF position. If valve does not open,
bend the lever until it does. If valve still fails to bleed,
replace the valve assembly.
Clean or replace air intake filter. Do not operate the
compressor in the paint spray area.
Restricted air intake filter.
Prolonged excessive use of air. Decrease amount of air usage.Compressor is not supplying
enough air to operate accesso-
ries. Compressor is not large enough for air
requirement. Checkthe accessory airrequirement. If it ishigher than
theCFM or pressure supplied by your air compressor,
you need a larger compressor.
Excessivebelt wear. Adjust belt tension. (See Belt Replacement.)
Loose belt/tight belt.
Loose pulley. Check for worn keyway or pulley bore. Also check for
bent motor shaft. Replace parts if necessary.

20—ENG
MGP-SL10120H-2A
CORRECTION
CAUSEPROBLEM
TROUBLESHOOTING GUIDE
Compressor is not supplying
enough air to operate accesso-
ries. (Continued)
Loose belt.
Hole in hose. Check and replace if required.
Check valve restricted.
Adjust belt tension.
Remove and clean or replace.
Tighten fittings. (See "Air Leaks" section of "Trou-
bleshooting Guide".)
Air leaks.
Maintain prescribed oil level. Add oil.
Knocking noise. Defectivecheck valve. Remove and clean or replace.
Tighten pulley set screw, 145 to 165 in.-lbs.Loose pulley.
Low oil level.
Loose flywheel. Tighten screw, 33 to 37 ft.-lbs.
Loose compressor mounting screws. Check screws. Tighten as required.
Belt too tight/too loose. Adjust belt tension. (See Belt Replacement.)
Carbon build-up. Remove the head. Clean the valves and the top of the
piston.(Be sure carbon does not fall into the cylinder.)
Reassemble using new gaskets and torque screws,
117-207 ft.-lbs.
Excessive oil consumption. Replace the air intake.
Restricted air intake.
Reduceair consumption or add another air compres-
sor to take up some of the load.
Compressoroverworked.
Drain pump and replace with correct oil. Refer to
Lubrication and Oil Section.
Poor quality oil.
Compressor overheating. The compressor is overworked. Reduceair consumption or add another air compres-
sor to take up some of the load.
Inspect the check valve. Clean if necessary.
Dirtycompressor. Clean the compressor thoroughly.
High ambient temperature. Use remote air intake.
The check valve is restricted.
Incorrect oil, low oil. See oil recommendation under Maintenance.
Motor overheating.
Dirty or defective check valve.Compressor starting against load.
Low voltage. Provide correct voltage. Consult local power com-
pany or electrician.
Do not set switch beyond maximum for which outfit
was designed as noted on nameplate.
Pressureswitch set beyond factory set-
ting.
Belt too tight. Adjust for proper tension.
Compressorvalves have excessivecar-
bondeposits build-up; restricted check
valve.
Clean or replace compressor valves or check valve.