Generac 004475-1, 004370-2, 004189-1, 004371-2, 004188-1 User Manual

POWER SYSTEMS, INC.

®

Owner’s Manual

Liquid-cooled, Prepackaged

Standby Generators

Model Numbers

(Natural Gas)

004188-1
004370-2
004474-1

(Liquid Propane Vapor)

004189-1
004371-2
004475-1

ONLY QUALIFIED ELECTRICIANS OR CONTRACTORS

SHOULD ATTEMPT INSTALLATION!!

Generac®Power Systems, Inc.

INTRODUCTION

Thank you for purchasing this model of the standby gen­erator set product line by Generac Power Systems.

Every effort was expended to make sure that the infor­mation and instructions in this manual were both accu­rate and current at the time the manual was written.
However, the manufacturer reserves the right to change,
alter or otherwise improve this product(s) at any time
without prior notice.

READ THIS MANUAL THOROUGHLY

If you do not understand any portion of this manual,
contact Generac or your nearest Generac Authorized
Service Dealer for starting, operating and servicing pro­cedures.

Throughout this publication, and on tags and
decals affixed to the generator, DANGER, WARNING,
CAUTION and NOTE blocks are used to alert you to spe­cial instruction about a particular service or operation
that may be hazardous if performed incorrectly or care­lessly. Observe them carefully. Their definitions are as fol­lows:

After this heading, you can read instructions that, if
not strictly complied with, will result in personal injury
or property damage.

After this heading, you can read instructions that, if not
strictly complied with, may result in personal injury or
property damage.

After this heading, you can read instructions that, if not
strictly complied with, could result in damage to equip­ment and/or property.

NOTE:

After this heading, you can read explanatory state­ments that require special emphasis.

These safety warnings cannot eliminate the hazards that
they indicate. Common sense and strict compliance with
the special instructions while performing the service are
essential to preventing accidents.

Four commonly used safety symbols accompany the
DANGER, WARNING and CAUTION blocks. The type of
information each indicates is as follows:

This symbol points out important safety information
that, if not followed, could endanger personal safety
and/or property of you and others.

This symbol points out potential explosion hazard.

This symbol points out potential fire hazard.

This symbol points out potential electrical shock
hazard.

The operator is responsible for proper and safe use of
the equipment. We strongly recommend that the opera­tor read this Owner's Manual and thoroughly under­stand all instructions before using this equipment. We
also strongly recommend instructing other users to
properly start and operate the unit. This prepares them
if they need to operate the equipment in an emergency.

OPERATION AND MAINTENANCE

It is the operator's responsibility to perform all safety
checks, to make sure that all maintenance for safe oper­ation is performed promptly, and to have the equipment
checked periodically by a Generac Authorized Service
Dealer. Normal maintenance service and replacement of
parts are the responsibility of the owner/operator and,
as such, are not considered defects in materials or work­manship within the terms of the warranty. Individual
operating habits and usage contribute to the need for
maintenance service.

Proper maintenance and care of your generator ensure a
minimum number of problems and keep operating
expenses at a minimum. See your Generac Authorized
Service Dealer for service aids and accessories.

Operating instructions presented in this manual
assume that the standby electric system has been
installed by a Generac Authorized Service Dealer or
other competent, qualified contractor. Installation of
this equipment is not a “do-it-yourself” project.

HOW TO OBTAIN SERVICE

When your generator requires servicing or repairs, sim­ply contact a Generac Authorized Service Dealer for
assistance. Service technicians are factory-trained and
are capable of handling all of your service needs.

When contacting a Generac Authorized Service Dealer
or the factory about parts and service, always supply the
complete model number of your unit as given on the
front cover of this manual or on the DATA CARD affixed
to the unit.

AUTHORIZED SERVICE

DEALER LOCATION

To locate the GENERAC AUTHORIZED SERVICE

DEALER nearest you, please call this number:

1-800-333-1322

OR

Locate us on the web at:

www.generac.com

Table of Contents

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

Generac®Power Systems, Inc. 1

INTRODUCTION ....................................IFC

SAFETY RULES..........................................2

Section 1

GENERAL INFORMATION ......................4

Generator ..................................................................4

Transfer Switch ........................................................4

Automatic System Operation ....................................4

Generator AC Connection Systems ............................4

Main Circuit Breaker ................................................5

Generator Fuel System ..............................................5

Engine Protective Devices ..........................................5

Unpacking..................................................................6

Lifting the Generator..................................................6

Specifications ............................................................6

Fuel Consumption......................................................7

Torque Specifications ................................................7

Engine Oil Recommendations ....................................7

Coolant Recommendations ........................................7

Before Installation......................................................7

Section 2

STANDBY GENERATOR INSTALLATION..8

Generator Location ....................................................8

Generator Mounting and Support..............................9

Basic Standby Electric System ..................................9

Emergency Circuit Isolation Method ..........................9

Total Circuit Isolation Method....................................9

Grounding the Generator ..........................................9

Generator AC Neutral Connections ..........................10

Transfer Switch Start Signal Connections ..............10

Battery Installation ..................................................10

Preparation Before Start-Up ....................................11

Section 3

OPERATION ..........................................11

Using a Standard “GTS” Transfer Switch ................11

Control Console Components ..................................12

Manual Transfer and Startup ..................................13

Retransfer and Shutdown ........................................13

Automatic Operation................................................13

Weekly Exercise Cycle ..............................................13

Engine Heater ..........................................................14

Section 4

MAINTENANCE ....................................14

Maintenance Performed by

Authorized Service Facilities ....................................14

Overload Protection for Engine DC

Electrical System ....................................................14

Checking Fluid Levels ..............................................14

Maintenance Owner/Operator Can Perform..............15

Miscellaneous Maintenance......................................17

Section 5

TROUBLESHOOTING ............................18

Section 6

SCHEDULED MAINTENANCE ................19

Section 7

WIRING DIAGRAMS AND

SCHEMATICS ........................................22

Section 8

EXPLODED VIEWS AND

PARTS LISTS ........................................27

Section 9

INSTALLATION DRAWINGS ..................52

Section 10

WARRANTY ...........................................56

2 Generac®Power Systems, Inc.

Study these SAFETY RULES carefully before installing,
operating or servicing this equipment. Become familiar
with this Owner’s Manual and with the unit. The genera­tor can operate safely, efficiently and reliably only if it is
properly installed, operated and maintained. Many acci­dents are caused by failing to follow simple and funda­mental rules or precautions.

Generac cannot possibly anticipate every possible cir­cumstance that might involve a hazard. The warnings in

this manual, and on tags and decals
affixed to the unit are, therefore, not all-inclusive. If you
use a procedure, work method or operating technique
that Generac does not specifically recommend, you
must satisfy yourself that it is safe for you and others.
You also must make sure the procedure, work method
or operating technique that you choose does not render
the generator unsafe.

Despite the safe design of this generator,
operating this equipment imprudently, neglecting its
maintenance or being careless can cause
possible injury or death. Permit only responsible and
capable persons to install, operate or maintain this
equipment.

Potentially lethal voltages are generated by these
machines. Ensure all steps are taken to render the
machine safe before attempting to work on the
generator.

Parts of the generator are rotating and/or hot
during operation. Exercise care near running gen­erators.

GENER

AL HAZARDS

• For safety reasons, Generac recommends that this
equipment be installed, serviced and repaired by a
Generac Authorized Service Dealer or other compe­tent, qualified electrician or installation technician
who is familiar with applicable codes, standards and
regulations. The operator also must comply with all
such codes, standards and regulations.

• Installation, operation, servicing and repair of this
(and related) equipment must always comply with
applicable codes, standards, laws and regulations.
Adhere strictly to local, state and national electrical
and building codes. Comply with regulations the
Occupational Safety and Health Administration
(OSHA) has established. Also, ensure that the gener­ator is installed, operated and serviced in accordance
with the manufacturer’s instructions and recommen­dations. Following installation, you must not do any­thing that might render the unit unsafe or in non­compliance with the aforementioned codes, stan­dards, laws and regulations.

• The engine exhaust fumes contain carbon monoxide
gas, which can be DEADLY. This dangerous gas, if
breathed in sufficient concentrations, can cause
unconsciousness or even death. For that reason, ade­quate ventilation must be provided. Exhaust gases
must be piped safely away from any building or
enclosure that houses the generator to an area where
people, animals, etc., will not be harmed. This
exhaust system must be installed properly, in strict
compliance with applicable codes and standards.

• Keep hands, feet, clothing, etc., away from drive belts,
fans, and other moving or hot parts. Never remove
any drive belt or fan guard while the unit is operating.

• Adequate, unobstructed flow of cooling and ventilat­ing air is critical to prevent buildup of explosive gases
and to ensure correct generator operation. Do not
alter the installation or permit even partial blockage
of ventilation provisions, as this can seriously affect
safe operation of the generator.

• Keep the area around the generator clean and unclut­tered. Remove any materials that could become haz­ardous.

• When working on this equipment, remain alert at all
times. Never work on the equipment when you are
physically or mentally fatigued.

Important Safety Instructions

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

SAVE THESE INSTRUCTIONS – The manufacturer suggests that these rules for safe
operation be copied and posted in potential hazard areas. Safety should be stressed to all
operators, potential operators, and service and repair technicians for this equipment.

SAVE THESE INSTRUCTIONS – This manual contains important instructions that should be
followed during installation and maintenance of the generator and batteries.

The engine exhaust from this product

contains chemicals known to the state

of California to cause cancer, birth

defects or other reproductive harm.

WARNING:

This product contains or emits chemicals

known to the state of California to cause

cancer, birth defects or other reproductive harm.

WARNING:

Generac®Power Systems, Inc. 3

• Inspect the generator regularly, and promptly repair
or replace all worn, damaged or defective parts using
only factory-approved parts.

• Before performing any maintenance on the generator,
disconnect its battery cables to prevent accidental
start-up. Disconnect the cable from the battery post
indicated by a NEGATIVE, NEG or (–) first.
Reconnect that cable last.

• Never use the generator or any of its parts as a step.
Stepping on the unit can stress and break parts, and
may result in dangerous operating conditions from
leaking exhaust gases, fuel leakage, oil leakage, etc.

ELE

CTRICAL HAZARDS

• All generators covered by this manual produce dan­gerous electrical voltages and can cause fatal electrical
shock. Utility power delivers extremely high and dan­gerous voltages to the transfer switch as well as the
standby generator. Avoid contact with bare wires, ter­minals, connections, etc., on the generator as well as
the transfer switch, if applicable. Ensure all appropri­ate covers, guards and barriers are in place before
operating the generator. If you must work around an
operating unit, stand on an insulated, dry surface to
reduce shock hazard.

• Do not handle any kind of electrical device while
standing in water, while barefoot, or while hands or
feet are wet. DANGEROUS ELECTRICAL SHOCK

MAY RESULT.

• If people must stand on metal or concrete while
installing, operating, servicing, adjusting or repairing
this equipment, place insulative mats over a dry
wooden platform. Work on the equipment only while
standing on such insulative mats.

• The National Electrical Code (NEC), Article 250
requires the frame and external electrically conduc­tive parts of the generator to be connected to an
approved earth ground and/or grounding rods. This
grounding will help prevent dangerous electrical
shock that might be caused by a ground fault condi­tion in the generator set or by static electricity. Never
disconnect the ground wire.

• Wire gauge sizes of electrical wiring, cables and cord
sets must be adequate to handle the maximum elec­trical current (ampacity) to which they will be sub­jected.

• Before installing or servicing this (and related) equip­ment, make sure that all power voltage supplies are
positively turned off at their source. Failure to do so
will result in hazardous and possibly fatal electrical
shock.

• Connecting this unit to an electrical system normally
supplied by an electric utility shall be by means of a
transfer switch so as to isolate the generator electric
system from the electric utility distribution system
when the generator is operating. Failure to isolate the
two electric system power sources from each other by
such means will result in damage to the generator
and may also result in injury or death to utility power
workers due to backfeed of electrical energy.

• Generators installed with an automatic transfer
switch will crank and start automatically when nor­mal (utility) source voltage is removed or is below an
acceptable preset level. To prevent such automatic
start-up and possible injury to personnel, disable the
generator’s automatic start circuit (battery cables,
etc.) before working on or around the unit. Then,
place a “Do Not Operate” tag on the generator control
panel and on the transfer switch.

• In case of accident caused by electric shock, immedi­ately shut down the source of electrical power. If this
is not possible, attempt to free the victim from the
live conductor. AVOID DIRECT CONTACT WITH
THE VICTIM. Use a nonconducting implement, such
as a dry rope or board, to free the victim from the live
conductor. If the victim is unconscious, apply first aid
and get immediate medical help.

• Never wear jewelry when working on this equipment.
Jewelry can conduct electricity resulting in electric
shock, or may get caught in moving components
causing injury.

F

IRE HAZARDS

• Keep a fire extinguisher near the generator at all
times. Do NOT use any carbon tetra-chloride type
extinguisher. Its fumes are toxic, and the liquid can
deteriorate wiring insulation. Keep the extinguisher
properly charged and be familiar with its use. If you
have any question pertaining to fire extinguishers,
consult your local fire department.

EXPLOSION HAZARDS

• Properly ventilate any room or building housing the
generator to prevent build-up of explosive gas.

• Do not smoke around the generator. Wipe up any fuel
or oil spills immediately. Ensure that no combustible
materials are left in the generator compartment, or
on or near the generator, as FIRE or EXPLOSION
may result. Keep the area surrounding the generator
clean and free from debris.

• Generac generator sets may operate using one of sev­eral types of fuels. All fuel types are potentially FLAM­MABLE and/or EXPLOSIVE and should be handled
with care. Comply with all laws regulating the storage
and handling of fuels. Inspect the unit’s fuel system
frequently and correct any leaks immediately. Fuel
supply lines must be properly installed, purged and
leak tested according to applicable fuel-gas codes
before placing this equipment into service.

• Diesel fuels are highly FLAMMABLE. Gaseous fluids
such as natural gas and liquid propane (LP) gas are
extremely EXPLOSIVE. Natural gas is lighter than air,
and LP gas is heavier than air; install leak detectors
accordingly.

Important Safety Instructions

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

4 Generac®Power Systems, Inc.

GENERATOR

This equipment is a liquid-cooled, engine-driven gener­ator set. The generator is designed to supply electrical
power that operates critical electrical loads during util­ity power failure. The unit has been factory-installed in
a weather resistant, all metal enclosure and is intended
for outdoor installation only. Use this generator as a
source of electrical power for the operation of 120
and/or 240 volts, single phase loads.

These models are available. They are rated as follows:

Model 004188: Provides 15,000 watts (15 kW) of 1 phase power.

Model 004189: Provides 15,000 watts (15 kW) of 1 phase power.

Model 004370: Provides 20,000 watts (20 kW) of 1-phase power.

Model 004371: Provides 20,000 watts (20 kW) of 1-phase power.

Model 004474: Provides 25,000 watts (25 kW) of 1 phase power.

Model 004475: Provides 25,000 watts (25 kW) of 1 phase power.

If this generator is used to power electrical load
circuits normally powered by a utility power
source, you are required by code to install a
transfer switch. The transfer switch must effec­tively isolate the electric system from the utility
distribution system when the generator is oper­ating (NEC 701). Failure to isolate an electrical
system by such means results in damage to the
generator and may also result in injury or even
death to utility power workers due to backfeed
of electrical energy.

TRANSFER SWITCH

This Guardian system includes a matched automatic
transfer switch which is intended to be used in con­junction with your Guardian generator. It is supplied in
either a NEMA 1 enclosure (15 kW models 004188, and
004189, and 20 kW models 004370, and 004371) or a
NEMA 3R enclosure (25 kW models 004474 and

004475). The NEMA 1 enclosure is intended for indoor
use only. The NEMA 3R enclosure is weather proof and
can be used indoors or outdoors. Follow these rules:

• Install the transfer switch on a firm, sturdy support­ing structure.

• To prevent switch distortion, level the switch if neces­sary. This can be done by placing washers between
the switch enclosure and the mounting surface.

• Never install the switch where water or any corrosive
substance might drip onto the enclosure.

• Protect the switch at all times against excessive mois­ture, dust, dirt, lint, construction grit and corrosive
vapors.

AUTOMATIC SYSTEM OPERATION

When this generator, along with its transfer switch, has
been installed and interconnected, a circuit board in the
generator panel constantly monitors utility power
source voltage. Should that voltage drop below a preset
value, and remain at such a low state for a preset
amount of time, the generator cranks and starts. After
the generator starts, the transfer switch transfers load
circuits so the generator can power them.

When utility source voltage has been restored, the
switch re-transfers back to the utility source voltage and
the generator then shuts down.

GENERATOR AC CONNECTION SYSTEMS

The generator was shipped from the factory with its sta­tor AC output leads connected in a single-phase, 3-wire
generator AC connection system (Figure 1.1). The stator
assembly in this system consists of a pair of stationary
windings, with two leads brought out of each winding.
Each single winding can supply 120 volts AC, 60 Hertz.
When the two windings are connected in series, a 240
volts, 60 Hertz AC output results. Typically the two “hot”
leads in the circuit are Wires No. 11 and 44. The
“Neutral” leads are the junction of Wires 22 and 33.

Figure 1.1 - Generator AC Connection System

MAIN CIRCUIT BREAKER

The generator’s main circuit breaker is included with
the unit as shipped from the factory. The breaker for
each unit is described in Figure 1.2 at the top of page 5.

GENERATOR FUEL SYSTEM

Your unit has been factory tested and adjusted using a
natural gas fuel system. If propane (LP) gas is preferred,
contact an authorized service dealer.

Section 1 - General Information

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

Generac®Power Systems, Inc. 5

Gaseous fuels such as natural and LP (propane)
gas are highly explosive. Even the slightest
spark can ignite such fuels and cause an explo­sion. No leakage of fuel is permitted. Natural
gas, which is lighter than air, tends to collect in
high areas. LP gas is heavier than air and tends
to settle in low areas.

ENGINE PROTECTIVE DEVICES

The engine has several safety switches which cause the
engine to automatically shut down under the following
conditions: low oil pressure, high coolant temperature,
engine overspeed, low coolant level or overcrank (Figure

1.3).

Figure 1.3 - Engine Protective Devices

LOW OIL PRESSURE SWITCH

This switch is normally-closed (N.C.) but is held open
by engine oil pressure during engine running. Should
operating oil pressure drop below about 8-10 psi (55-68
kPa), the switch contacts close and the engine shuts
down automatically (Figure 1.4).

Figure 1.4 - Low Oil Pressure Switch

HIGH COOLANT TEMPERATURE SWITCH

Normally open (N.O.) thermostatic switch has sensing
tip which is immersed in captive coolant. Should
coolant temperature exceed about 230°F (110°C), the
switch contacts close, which causes the engine to shut
down automatically (Figure 1.5).

Figure 1.5- High Coolant Temperature Switch

LOW COOLANT LEVEL SWITCH

Should engine coolant level drop below the level of the
high coolant temperature switch, it is possible for the
engine to overheat without automatic shutdown. To
prevent such overheating without automatic shut down,
the engine has a low coolant level sensor. If the engine
coolant drops too low, the engine automatically shuts
down (Figure 1.6).

Section 1 - General Information

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

Model Rating Phase Actual Current C/B Rating* % over rating Circuit Breaker

004188 15,000 1 62.5 70 112% 70A BQ2
004189 15,000 1 62.5 70 112% 70A BQ2
004370 20,000 1 83.3 90 108% 90A BQ2
004371 20,000 1 83.3 90 108% 90A BQ2
004474 25,000 1 104.2 125 120% 125A BQ2
004475 25,000 1 104.2 125 120% 125A BQ2

* Amp Rating of C/B structured under model.

Figure 1.2 - Main Circuit Breaker

6 Generac®Power Systems, Inc.

Figure 1.6 - Low Coolant Level Sensor

OVERSPEED SHUTDOWN

The CMA circuit board on liquid cooled units receives
AC frequency (rpm) signals directly from the stator AC
power windings, via sensing leads S15 and S16. Should
AC frequency exceed about 72 Hz, circuit board action
will automatically shutdown the engine (Figure 1.7).

*Rated power of generator is subject to and limited
by such factors as ambient temperature, altitude,
engine condition, and other factors. Engine power
will decrease about 3.5% for each 1000 feet above
sea level and will decrease an additional 1% for each
10°F above 60°F. Maximum output power of the gen­erator is limited by maximum engine power.

Figure 1.7 - Control Module Assembly

Circuit Board

OVERCRANK SHUTDOWN

After 90 seconds of crank-rest cycles, this function ends
cranking if the engine fails to start in that 90-second
span.

DC FUSE

This clearly labeled fuse is located on the front panel of
the control system. It protects the panel wiring and com­ponents from damaging overload. Always remove this
fuse before commencing work on the generator. The
unit will not start or crank if the fuse is blown. Replace
the fuse with one of the same size, type, and rating.
Generac normally uses an AGC fuse rated at 30 amps.

UNPACKING

UNPACKING PRECAUTIONS

Handle shipping cartons and crates with care. Use care
to avoid damage from dropping, bumping, collision, etc.
Store and unpack cartons with the proper side up, as
noted on the shipping carton.

INSPECTION

After unpacking, carefully inspect the generator for any
damage that may have occurred during shipment. If
loss or damage is noted at the time of delivery, have the
person(s) making delivery note all damage on the freight
bill or affix his signature under the consignor’s memo of
loss or damage.

LIFTING THE GENERATOR

When lifting or hoisting equipment is used, be
careful not to touch overhead power lines. The
generators weight of more than 900 pounds
requires proper tools, equipment, and qualified
personnel to be used in all phases of handling
and unpacking.

SPECIFICATIONS

GENERATOR SPECIFICATIONS

Section 1 — General Information

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

1-Phase

Model 4474 4370 4188

4475 4371 4189
*Rated Max. Cont. 25 20 15
AC Power Output (kW)
Rated voltage (volts) 120/240
No. of Rotor Poles 2 4
Driven Speed of Rotor 3600 3600 1800
Rotor Excitation System Direct excited brush type
Type of Stator 4 Wire
Rotor/Stator Insulation Class F

ENGINE SPECIFICATIONS

Make ..................................................................................Mitsubishi

Displacement ....................................................92 inches3(1.5 liters)

Cylinder Arrangement ..........................................................4, in-line

Valve Arrangement ....................................................Overhead Cam

Firing Order ............................................................................1-3-4-2

Number of Main Bearings ................................................................5

Compression Ratio....................................................................9 to 1

No. of Teeth on Flywheel ..............................................................104

Ignition Timing

at 1800 rpm ........................................................35 degrees BTDC

at 3600 rpm ........................................................43 degrees BTDC

Spark Plug Gap ......................................................0.020-0.025 inch

Recommended Spark Plugs

Champion ........................................................................RN11YC4

Oil Pressure ........................................................................30-50 psi

Crankcase Oil Capacity ............................4.0 U.S. quarts (3.8 liters)

Recommended Engine Oil ............................................SAE 15W-40

Type of Cooling System ......................Pressurized, closed recovery

Cooling Fan ....................................................................Pusher Type

Cooling System Capacity............................2 U.S. gallons (7.6 liters)

Recommended Coolant ................................Use a 50-50 mixture of

ethylene glycol base.

FUEL CONSUMPTION

Models 004474, 004475

Using Natural Gas ..............................................441 cu. ft. per hour

Using LP Gas ..................................175 cubic ft.(4.8 gal.) per hour

Models 004370, 004371

Using Natural Gas ..............................................359 cu. ft. per hour

Using LP Gas ..................................143 cubic ft. (4.0 gal.) per hour

Models 004188, 004189

Using Natural Gas ..............................................277 cu. ft. per hour

Using LP Gas ..................................110 cubic ft.(3.1 gal.) per hour

NOTE:

Fuel consumption is given at rated maximum con­tinuous power output when using natural gas rated
at 1000 Btu per cubic foot; or LP gas rated 2520 Btu
per cubic foot. Actual fuel consumption obtained
may vary depending on such variables as applied
load, ambient temperature, engine conditions and
other environmental factors.

TORQUE SPECIFICATIONS

Cylinder Head ..................................................15 (+ 90° + 90°) ft.lb.

Intake Manifold ......................................................................13 ft.lb.

Exhaust Manifold ..................................................................13 ft.lb.

ENGINE OIL RECOMMENDATIONS

The unit has been filled with 15W-40 engine oil at the fac­tory. Use a high-quality detergent oil classified “For
Service CC, SD, SE, SF.” Detergent oils keep the engine
cleaner and reduce carbon deposits. Use oil having the
following SAE viscosity rating, based on the ambient tem­perature range anticipated before the next oil change:

Any attempt to crank or start the engine before
it has been properly serviced with the recom­mended oil may result in an engine failure.

COOLANT RECOMMENDATIONS

Use a mixture of half low silicate ethylene glycol base
anti-freeze and half soft water. Cooling system capacity
is about 8 U.S. quarts (7.6 liters). Use only soft water
and only low silicate anti-freeze. If desired, add a high
quality rust inhibitor to the recommended coolant mix­ture. When adding coolant, always add the recommend­ed 50-50 mixture.

Do not use any chromate base rust inhibitor
with ethylene glycol base anti-freeze or chromi­umhydroxide (“green slime”) forms and will
cause overheating. Engines that have been oper­ated with a chromate base rust inhibitor must be
chemically cleaned before adding ethylene glycol
base anti-freeze. Using any high silicate anti­freeze boosters or additives will also cause over­heating. We also recommend that you DO NOT
use any soluble oil inhibitor for this equipment.

BEFORE INSTALLATION

Before installing this equipment, check the ratings of both
the generator and the transfer switch. Read “Emergency
Isolation Method” and “Total Circuit Isolation Method” in
the installation manual (Part No. 079699).

The generator’s rated wattage/amperage capacity must
be adequate to handle all electrical loads that the unit
will power. You may have to group the critical (essential)
loads together and wire them into a separate “emer­gency” distribution panel.

This generator can be installed in conjunction with a
standard Generac “GTS” type transfer switch, if desired.

The standard transfer switch has no sensing or con­trolling circuit boards. Instead, the generator control
console houses a “Control Module Assembly”, which
controls all phases of operation, including engine start
up and load transfer.

Section 1 — General Information

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

Generac®Power Systems, Inc. 7

Temperature Oil Grade (Recommended)

Above 80° F (27° C) SAE 30W or 15W-40

32° to 80° F (-1° to 27° C) SAE 20W-20 or 15W-40

Below 32° F (0° C) SAE 10W or 15W-40

8 Generac®Power Systems, Inc.

If an open bottom is used, the engine-generator is
to be installed over non-combustible materials
and should be located such that combustible
materials are not capable of accumulating under
the generator set.

Only qualified, competent installation contractors or
electricians thoroughly familiar with applicable codes,
standards and regulations should install this standby
electric power system. The installation must comply
strictly with all codes, standards and regulations per­taining to the installation.

After the system has been installed, you must not
do anything that might render the installation in
noncompliance with such codes, standards and
regulations.

NOTE:

For more information about the installation of a stand­by system, you can order Engine-Generator Standby

Electric Power Systems Installer’s Guide and
Reference Manual (part #046622) from your Generac

Authorized Service Dealer.

NFPA STANDARDS

The following published standards booklets pertaining
to standby electric systems are available form the
National Fire Protection Association (NFPA),
Batterymarch Park, Quincy, MA 02269:

• NFPA No. 37, STATIONARY COMBUSTION ENGINES
AND GAS TURBINES.

• NFPA No. 76A, ESSENTIAL ELECTRICAL SYSTEMS
FOR HEALTH CARE FACILITIES.

• NFPA No. 220, STANDARD TYPES OF BUILDING
CONSTRUCTION

• NFPA No. 68, GUIDE FOR EXPLOSION VENTING

• NFPA No. 70, NATIONAL ELECTRICAL CODE.

• NFPA No. 30, FLAMMABLE AND COMBUSTIBLE
LIQUIDS CODE.

• NFPA No. 10, INSTALLATION, MAINTENANCE AND
USE OF PORTABLE FIRE EXTINGUISHERS.

OTHER PUBLISHED STANDARDS

In addition to NFPA standards, the following informa­tion pertaining to the installation and use of standby
electric systems is available:

• Article X, NATIONAL BUILDING CODE, available
from the American Insurance Association, 85 John
Street, New York, N.Y. 10038.

• AGRICULTURAL WIRING HANDBOOK, obtainable
from the Food and Energy Council, 909 University
Avenue, Columbia, MO, 65201.

• ASAE EP-364.2, INSTALLATION AND MAINTE­NANCE OF FARM STANDBY ELECTRIC POWER,
available from the American Society of Agricultural
Engineers, 2950 Niles Road, St. Joseph, MI 49085.

• A52.1, AMERICAN NATIONAL STANDARD FOR
CHIMNEYS, FIREPLACES AND VENTING SYS­TEMS, available from the American National
Standard Institute, 1430 Broadway, New York, N.Y.

10018.

GENERATOR LOCATION

Install the generator set, in its protective enclosure out­doors, where adequate cooling and ventilating air
always is available. Consider these factors:

• Install the unit where air inlet and outlet openings
will not become obstructed by leaves, grass, snow,
etc. If prevailing winds will cause blowing or drifting,
you may need to consider using a windbreak to pro­tect the unit.

• Install the generator on high ground where water lev­els will not rise and endanger it.

• Allow sufficient room on all sides of the generator for
maintenance and servicing. A good rule is to allow 3
feet of space on all sides.

• Where strong prevailing winds blow from one direc­tion, face the generator air inlet openings into the pre­vailing winds.

• Install the generator as close as possible to the trans­fer switch. This reduces the length of wiring and con­duit.

• Install the generator as close as possible to the fuel
supply, to reduce the length of piping. HOWEVER,
REMEMBER THAT LAWS OR CODES MAY REGU­LATE THE DISTANCE.

Section 2 — Installation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

STANDBY GENERATOR INSTALLATION

Connecting this generator to an electrical system normally supplied by an electric utility shall be by
means of a transfer switch, so as to isolate the electric system from the utility distribution system
when the generator is operating. Failure to isolate the electric system by these means will result in
damage to the generator and may also result in injury or death to utility workers due to backfeed of
electrical energy.

Generac®Power Systems, Inc. 9

GENERATOR MOUNTING AND SUPPORT

Retain the generator compartment to a concrete slab
with 1/4-inch masonry type anchor bolts. Be sure the
bolts are long enough to retain the compartment. The
slab should be at least 6 inches thick and should extend
beyond the enclosure to a distance of at least 3 inches
on all sides. See pages 54-55 for generator major
dimensions.

BASIC STANDBY ELECTRIC SYSTEM

Figure 2.1 shows a schematic diagram of a basic stand­by electric system. Both the UTILITY power supply and
the STANDBY (generator) output are connected to an
approved transfer switch. The transfer switch is
required by electrical code and serves the following
functions:

• Permits the LOAD circuits to be connected to only one
power supply at a time.

• Prevents electrical backfeed between the generator
and the UTILITY power circuits.

Notice that both the STANDBY and the UTILITY power
supplies to the transfer switch are protected against
overload by a main line circuit breaker.

NOTE:

Generac recommends the use of a Generac power
systems “GTS” type transfer switch in conjunction
with this generator.

Figure 2.1 – Basic Standby Electric System

EMERGENCY CIRCUIT ISOLATION
METHOD

This prevents overloading the generator by keeping elec­trical loads below the wattage/amperage capacity of the
generator. If the generator is powering only critical
loads, within the wattage/amperage capacity, during util­ity power outages, you might consider using the emer­gency circuit isolation method.

Critical electrical loads are grouped together and wired
into a separate “Emergency Distribution Panel.” Load
circuits powered by that panel are within the
wattage/amperage capacity of the generator set. When
this method is used, it is difficult to overload the gener­ator. The transfer switch must meet the following
requirements:

• It must have an ampere rating equal to the total
amperage rating of the emergency distribution panel
circuit.

• Have it installed between the building’s main distri­bution panel and the emergency distribution panel.

TOTAL CIRCUIT ISOLATION METHOD

When a generator capable of powering all electrical
loads in the circuit is to be installed, you may use the
“Total Circuit Isolation Method.” It is possible for the
generator to be overloaded when this isolation method
is employed. The following apply to the transfer switch
in this type of system.

• Ampere rating of the transfer switch must equal the
ampere rating of the normal incoming utility service.

• The transfer switch is installed between the utility
service entrance and the building distribution panel.

GROUNDING THE GENERATOR

The National Electrical Code requires the frame and
external electrically conductive parts of this equipment
to be properly connected to an approved earth ground
and/or grounding rods. For that purpose, a GROUND
LUG (Figure 2.2) is provided on the generator mounting
base. Consult a qualified electrician for grounding
requirements in your area. Grounding procedures must
meet local regulations.

Do not connect the ground wire to any pipe that
carries a flammable or explosive substance – FIRE
or an EXPLOSION may result.

Proper grounding helps protect personnel against elec­trical shock in the event of a ground fault condition in
the generator or in connected electrical devices. In addi­tion, grounding helps dissipate static electricity that
often builds up in ungrounded devices.

Figure 2.2 – Generator Grounding Lug (typical)

Section 2 — Installation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

10 Generac®Power Systems, Inc.

GENERATOR AC NEUTRAL CONNECTIONS

Generac uses an UNGROUNDED AC neutral.
Grounding is recommended only at the main service
entrance. If the neutral wire is grounded and one of the
phase loads becomes grounded, the excessive current
opens the load circuit breaker or collapses the genera­tor field. The actual result depends on the electrical
characteristics of the particular installed generator.

TRANSFER SWITCH START SIGNAL
CONNECTIONS

If your generator is to be installed with an automatic
transfer switch, such as a Generac GTS-type switch, it
will be necessary to connect the two-wire start
control system.

Connect the two-wire start signal from the automatic
transfer switch to the automatic start connection, which
is located in the right hand corner inside the control
panel. Match wires 178 and 183 in the transfer switch
to 178 and 183 on the terminal strip in the control
panel. The conductors for the two-wire start circuit
must be in their own conduit.

BATTERY INSTALLATION

Standby generators installed with automatic
transfer switches will crank and start automatical­ly when normal (utility) source voltage is removed
or is below an acceptable preset level. To prevent
such automatic start-up and possible injury to per­sonnel, do not connect battery cables until you
are certain that normal source voltage at the
transfer switch is correct and you are ready to
place the system into operation.

Storage batteries give off explosive hydrogen gas.
This gas can form an explosive mixture around
the battery for several hours after charging. The
slightest spark can ignite the gas and cause an
explosion. Such an explosion can shatter the bat­tery and cause blindness or other injury. Any area
that houses a storage battery must be properly
ventilated. Do not allow smoking, open flame,
sparks or any spark producing tools or equipment
near the battery.

Battery electrolyte fluid is an extremely caustic
sulfuric acid solution that can cause severe burns.
Do not permit fluid to contact eyes, skin, clothing,
painted surfaces, etc. Wear protective goggles,
protective clothing and gloves when handling a
battery. If you spill the fluid, flush the affected
area immediately with clear water.

Do not dispose of the battery in a fire. The bat­tery is capable of exploding.

Do not open or mutilate the battery. Released
electrolyte can be toxic and harmful to the skin
and eyes.

The battery represents a risk of high short circuit
current. When working on the battery, always
remove watches, rings or other metal objects, and
only use tools that have insulated handles.

VENTED BATTERIES

The electrolyte is a dilute sulfuric acid that is
harmful to the skin and eyes. It is electrically con­ductive and corrosive. The following procedures
are to be observed:

• Wear full eye protection and protective clothing,

• Where electrolyte contacts the skin, wash it off
immediately with water,

• Where electrolyte contacts the eyes, flush thoroughly
and immediately with water and seek medical atten­tion, and

• Spilled electrolyte is to be washed down with an acid­neutralizing agent. A common practice is to use a
solution of one pound (500 grams) bicarbonate of
soda to one gallon (4 liters) of water. The bicarbonate
of soda solution is to be added until the evidence of
reaction (foaming) has ceased. The resulting liquid is
to be flushed with water and the area dried.

Lead acid batteries present a risk of fire because
they generate hydrogen gas. The following proce­dure are to be followed:

• DO NOT SMOKE when near batteries,

• DO NOT cause flame or spark in battery area, and

• Discharge static electricity from body before touching
batteries by first touching a grounded metal surface.

Servicing of batteries is to be performed or supervised
by personnel knowledgeable of batteries and the
required precautions. Keep unauthorized personnel
away from batteries.

For recommended batteries, see “Specifications.” All
batteries must be at 100 percent state-of-charge before
they are installed on the generator.

When using maintenance-free batteries, it is not neces­sary to check the specific gravity or electrolyte level.
Have these procedures performed at the intervals spec­ified in Section 4, “Maintenance.” A negative ground sys­tem is used. Battery connections are shown on the
wiring diagrams. Make sure all batteries are correctly
connected and terminals are tight. Observe battery
polarity when connecting batteries to the generator set.

Note:

Damage will result if the battery connections are
made in reverse.

Section 2 — Installation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

Generac®Power Systems, Inc. 11

PREPARATION BEFORE START-UP

The instructions in this section assume that the stand­by generator has been properly installed, serviced, test­ed, adjusted and otherwise prepared for use by a com­petent, qualified installation contractor. Be sure to read
the “Safety Rules” on Pages 2 and 3, as well as all other
safety information in this manual, before attempting to
operate this (and related) equipment.

PRIOR TO INITIAL START-UP

Prior to initially starting the generator, it must be
properly prepared for use. Any attempt to crank
or start the engine before it has been properly
serviced with the recommended types and quanti­ties of engine fluids (oil, coolant, fuel, etc.) may
result in an engine failure.

Before starting the generator for the first time, the
installer must complete the following procedures. For
follow-up maintenance information and/or service inter­vals, please refer to Section 4, “Maintenance.”

Transfer Switch

If this generator is used to supply power to any electri­cal system normally powered by an electric utility, the
National Electrical Code requires that a transfer switch
be installed. The transfer switch prevents electrical
backfeed between two different electrical systems.
(For additional information, see the applicable transfer
switch manual for this unit.) The transfer switch, as
well as the generator and other standby components,
must be properly located and mounted in strict compli­ance with applicable codes, standards and regulations.

Fuel System

Make sure the fuel supply system to the generator (a)
delivers the correct fuel at the correct pressure and (b)
is properly purged and leak tested according to code.
No fuel leakage is permitted. See “Specifications” (Page

7) for more information.

Generator Set Lubrication

Check the engine crankcase oil level before operating
and add oil to the proper level – the dipstick “FULL”
mark. Never operate the engine with the oil level below
the dipstick “ADD” mark. See “Specifications” (Page 7)
and “Engine Oil Recommendations” (Page 8).

NOTE:

This engine is shipped from the manufacturer with
15W-40 oil. This oil should be changed after 30
hours of operation.

Engine Coolant

Have the engine cooling system properly filled with the
recommended coolant mixture. Check the system for
leaks and other problems. See “Specifications” and
“Coolant” (Page 7).

Belt Tension

Check the engine fan belt tension and condition prior to
placing the unit into service and at recommended
intervals. Belt tension is correct when a force of approx­imately 22 pounds (10 kg), applied midway between
pulleys, deflects the belt about 3/8- to 5/8-inch
(10 to 16 mm).

Electrical System

Make sure the generator is properly connected to an
approved earth ground and/or ground rod.

Make sure the generator battery is fully charged, prop­erly installed and interconnected, and ready for use.

Check to ensure that there are no loose electrical con­nections. Restrain any loose wires to keep them clear of
any moving generator set components.

USING A STANDARD “GTS” TRANSFER
SWITCH

When required, the pre-packaged standby generator
can be installed with a standard Generac “GTS” type
automatic transfer switch.

When you use a standard GTS type transfer switch, it
controls automatic operation and automatic transfer as
follows:

• Solid state circuits in the transfer switch monitor util­ity power source voltage.

• When utility source voltage drops below a pre-set level,
transfer switch action closes the circuit. The engine
then cranks and starts as controlled by the pre-pack­aged generator’s Control Module circuit board.

• After the engine starts and when the generator AC
output voltage and frequency have reached a pre-set
value, transfer switch circuits signal the transfer
switch main contacts to actuate to the “Standby”
power source side. Generator AC output then powers
load circuits.

• When the utility power source voltage is restored
above a pre-set level, transfer switch solid state cir­cuits signal the switch main contacts to move back to
their utility power source side.

• Following re-transfer back to the utility power source
side, transfer switch circuit board action opens the
circuit. Engine then shuts down.

NOTE:

If your generator is installed in conjunction with a
standard GTS type transfer switch, refer to the appli­cable transfer switch manual for exact operating
parameters and timing sequences.

▼ ▼ ▼

▼ ▼

▼

Section 3 - Operation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

12 Generac®Power Systems, Inc.

CONTROL CONSOLE COMPONENTS

The components of a liquid-cooled generator control
console (Figure 3.1) are as follows:

Figure 3.1 - Liquid-Cooled Generator Panel

AC VOLTMETER

The voltmeter displays generator AC output voltage dur­ing operation. Voltage is regulated by a solid state volt­age regulator and is proportional to AC frequency. Refer
to your unit’s DATA PLATE for rated AC voltage.

AC AMMETER

Indicated current draw of connected electrical loads
during operation. DO NOT EXCEED YOUR UNIT’S
RATED MAXIMUM CONTINUOUS CURRENT. Refer to
the unit DATA PLATE.

AC FREQUENCY METER

Indicates generator AC output frequency in “Hertz”
(cycles per second). Frequency is proportional to engine
speed. Units with a 4-pole rotor supplies 60 Hertz at
1800 rpm. Units with a 2-pole rotor supplies 60 Hz at
3600 rpm. Frequency reading with no electrical loads
connected (no-load condition) should be between 60-62
Hertz.

DC VOLTMETER

The generator is equipped with a belt-driven DC
alternator, which maintains battery state of charge when
the engine operates. The Control Module Assembly also
incorporates a trickle charge circuit which maintains
battery state of charge during non-operating periods.
Battery voltage should read about 12.5 to 14.5 volts DC.
A low battery voltage indicates the battery is
discharging.

HOURMETER

Indicates time the engine-generator has operated, in
hours and tenths of hours. Use the hourmeter along
with the periodic maintenance schedule for your gener­ator set.

AUTO/OFF/MANUAL SWITCH

Use this 3-position switch as follows:

• Set the switch to “Auto” for fully automatic operation.
See “Automatic Operation”.

• Set switch to “Manual” position to crank and start the
generator engine.

• Set switch to “Off ” position to shut down an operat­ing engine. With “Off” selected, operation will not be
possible.

With switch set to "auto", engine can crank and
start suddenly without warning. Such automatic
start up normally occurs when utility source
voltage drops below a pre-set level. To prevent
possible injury that might be caused by such
sudden starts, set AUTO/OFF/MANUAL switch to
"off" before working on or around the unit.
Then, place a "do not operate" tag on control
console.

FAULT INDICATOR LAMP

Lamp goes ON when one or more of the following
engine faults occurs and when engine shuts down.

• Low oil pressure • Overcrank

• High coolant temperature • Overspeed

• Low coolant level

30 AMP FUSE

Fuse protects the control console’s DC control circuit
against electrical overload. If the fuse has melted open
because of an overload, engine cranking and startup
cannot occur. Should you need to replace the fuse, use
only an identical 30-amp replacement fuse. (Type AGC)

7.5 AMP INLINE FUSE

This inline fuse is connected in the 15A line that runs
between the Auto/Off/Manual switch and position 10 of
the 76009A PCB. This fuse protects the start, fuel, field
boost, and transfer outputs from the PCB and will open
if there is excessive current draw on any one of these
outputs.

Section 3 — Operation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

30 AMP

FUSE

Generac®Power Systems, Inc. 13

NOTE:

This fuse will not remove the + battery input power
from the PCB when it opens. This means the exercise
timer will not be reset. If this fuse does open, care­fully check the wiring to the start, fuel, field boost
and transfer outputs before replacing the fuse.

METER READING SELECTOR SWITCH:

Switch permits you to select either line-to-line or
line-to-neutral voltage and amperage readings on the
console AC voltmeter and AC ammeter.

SET EXERCISE TIME SWITCH:

Switch allows you to program the generator to start and
exercise automatically. “See Weekly Exercise Cycle.”

MANUAL TRANSFER AND START UP

To transfer electrical loads to the “Standby” (generator)
power source side and start the engine manually, refer
to the Owner’s Manual of your particular transfer
switch.

RETRANSFER AND SHUTDOWN

When utility power source voltage has been restored,
electrical loads may be transferred back to that source
and the generator can be shut down as follows:

• Verify that utility power supply voltage to the transfer
switch has been positively turned “Off,” using what­ever means provided (such as utility main line circuit
breaker).

• Set the generator’s main circuit breaker to its “Off ” or
“Open” position.

• Let the generator engine run at no-load for a few min­utes, to stabilize internal unit temperatures.

• On the generator console, set the Auto-Off-Manual
switch to “Off”. Wait for engine to come to a complete
stop.

• For transfer to utility position, refer to the Owner’s
Manual of your particular transfer switch.

• Turn on the utility power supply to the transfer
switch, using whatever means provided (such as a
utility main line circuit breaker). The utility power
source now powers the loads.

AUTOMATIC OPERATION

To set the system for fully automatic operation, proceed
as follows:

• Check that load circuits are connected to the
utility power supply.

• Set the Auto/Off/Manual switch to its “Auto” position.

• Set the generator main circuit breaker to its “On” or
“Closed” position.

WEEKLY EXERCISE CYCLE

The generator will start and exercise once every 7 days.
During this weekly exercise, the unit runs for about 20
minutes and shuts down. Transfer of loads to genera­tor output does not occur during the exercise.

To select day and time for exercising, proceed as
follows:

• Set the Auto/Off/Manual switch to OFF.

• Set generator main circuit breaker to OFF or OPEN.

• Locate the rocker switch on the control panel identi­fied with the words “Set Exercise Time” (Figure 3.2).

• Push “Set Exercise Time” switch to ON position for
20 to 30 seconds and then release. Switch will spring
back into its original position when released.

• Wait 30 seconds before setting the Auto/Off/Manual
switch to “AUTO” position.

If you switch the Auto/Off/Manual switch too
soon, the engine may start. If engine does start,
it will shut down automatically in about two (2)
minutes.

• Set the generator main circuit breaker to its ON or
CLOSED position.

• Generator is now programmed to start and exercise
every 7 days thereafter, on day and time of day the
switch was actuated.

• Place a sign on the generator control panel and the
transfer switch, indicating the day and time the
generator will be exercising.

NOTE:

If battery terminals are disconnected or control
panel fuse is removed, the exercise timer needs to be
reset for correct automatic exercise operation.

Figure 3.2 - “Set Exercise” Switch

Section 3 - Operation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

14 Generac®Power Systems, Inc.

ENGINE HEATER

Your Generac standby generator comes equipped with a
block heater (Figure 4.1), similar to the block heaters
used in automotive applications. The block heater is
wired to a grounded plug.

Figure 4.1 - Engine Block Heater

Refer to applicable wiring diagram(s) and electrical
schematic(s) at back of manual for wiring connections.
Customer supplies a 120V 15A Utility fed circuit for the
block heater.

MAINTENANCE PERFORMED BY
AUTHORIZED SERVICE FACILITIES

A. EVERY THREE MONTHS

1.Check battery state of charge and condition.

2.Inspect and test fuel system.

3.Check transfer switch.

4.Inspect exhaust system.

5.Check engine ignition system.

6.Check fan belts.

B. ONCE EVERY SIX MONTHS

1.Test Engine Safety Devices (low oil pressure, low
coolant level, high coolant temperature).

C. ONCE ANNUALLY

1.Test engine governor; adjust or repair, if needed.

2.Clean, inspect generator.

3.Flush cooling system.

D. FIRST 100 OPERATING HOURS

1.Change engine oil and oil filter. (After initial change,
service engine oil and filter at 150 operating hours
or 6 months, whichever comes first.)

2.Retorque cylinder head. (See Torque Specs, page 7.)

3.Retorque intake and exhaust manifold. (See Torque
Specs, page 7.)

E. EVERY 500 OPERATING HOURS

1.Service air cleaner.

2.Check starter.

3.Check engine DC alternator.

F. EVERY 800 OPERATING HOURS

1.Retorque cylinder head. (See Torque Specs, page 7.)

2.Retorque intake and exhaust manifold. (See Torque
Specs, page 7.)

3.Check engine compression.

4.Check valve clearance.

COOLING SYSTEM

Air intake and outlet openings in the generator com­partment must be open and unobstructed for continued
proper operation. This includes such obstructions as
high grass, weeds, brush, leaves and snot.

Without sufficient cooling and ventilating air flow, the
engine/generator quickly overheats, which causes it to
shut down. (See Section 9 for installation drawings and
vent locations.)

The exhaust system parts from this product get
extremely hot and remains hot after shutdown.
High grass, weeds, brush, leaves, etc. must remain
clear of the exhaust. Such materials may ignite
and burn from the heat of the exhaust system.

OVERLOAD PROTECTION FOR ENGINE DC
ELECTRICAL SYSTEM

Engine cranking, start up and running are controlled by
a solid state Engine Controller circuit board. Battery
voltage is delivered to that circuit board via a 30 amp
fuse. These overcurrent protection devices will open if
the circuit is overloaded.

If a circuit breaker opens or a fuse element
melts, you should find the cause of the overload
before resetting the circuit breaker or replacing
the fuse.

CHECKING FLUID LEVELS

CHECK ENGINE OIL

Check engine crankcase oil level (Figure 4.2) at least
every 20 hours of operation, or prior to use.

• Remove oil dipstick and wipe dry with a clean,
lint-free cloth.

• Install oil dipstick, then remove again.

• Oil should be between FULL and ADD marks.

Section 4 — Maintenance

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

Generac®Power Systems, Inc. 15

• If oil level is below the dipstick ADD mark, remove oil
fill cap. Add the recommended oil to bring oil level
up to the FULL mark. DO NOT FILL ABOVE THE
“FULL” MARK. See page 6 for recommended oils.

Figure 4.2 - Oil Dipstick and Oil Fill Cap

BATTERY FLUID

Check battery electrolyte fluid at least once weekly.
Fluid should cover separators in all battery cells. If
fluid level is low, add distilled water to cover tops of sep­arators. DO NOT USE TAP WATER IN BATTERY.

ENGINE COOLANT

Check coolant level in coolant recovery bottle. See
Specifications, page 8

• Add recommended coolant mixture as necessary.

• Periodically remove radiator pressure cap to make
sure the coolant recovery system is functioning
properly. Coolant should be at bottom of radiator
filler neck. If coolant level is low, inspect gasket in
radiator pressure cap. Replace cap, if necessary. To
have pressure cap tested, contact an authorized
Generac Service Dealer. Inspect cooling system and
coolant recovery system for leaks.

MAINTENANCE OWNER/OPERATOR CAN
PERFORM

CHECK ENGINE OIL LEVEL

Refer to “Checking Fluid Levels” on page 15.

CHECK BATTERY

• Check battery fluid level each week as outlined under
“Check Fluid Levels”.

• Check battery cables for condition, tightness, corro­sion or damage. Clean, tighten or replace as
necessary.

EXERCISE SYSTEM

Start the generator engine at least once every seven days
and let it run at least 20 minutes. See page 14, “Weekly
Exercise Cycle”.

INSPECT COOLING SYSTEM

• Inspect engine cooling system at least once each
month.

• Check hoses for damage, deterioration, leaks, etc.
Correct any discrepancies found.

• Check hose clamps for tightness.

CHECK ENGINE COOLANT LEVEL

See “Checking Fluid Levels” on page 15.

PERFORM VISUAL INSPECTION

Complete a thorough visual inspection of the entire
engine-generator monthly. Look for obvious damage,
loose, missing or corroded nuts, bolts and other fasten­ers. Look for fuel, oil or coolant leaks.

INSPECT EXHAUST SYSTEM

Inspect the exhaust system at least once every three
months. Check all exhaust system pipes, mufflers,
clamps, etc. for condition, tightness, leaks, security,
damage.

CHECK FAN BELT

• Inspect fan belts every three months. Replace any
damaged, deteriorated, worn or otherwise defective
belt.

• Check fan belt tension. Thumb pressure, exerted
midway between pulleys, should deflect about 3/8 to
3/4 inch. Adjust belt tension as required.

INSPECT ENGINE GOVERNOR

Visually inspect electronic governor.

DANGER: Do not attempt to adjust the gover­nor. Only qualified service facilities should adjust
the governor. Excessively high operating speeds
are dangerous and increase the risk of personal
injury. Low speeds impose a heavy load on the
engine when adequate engine power is not
available and may shorten engine life. Correct
rated frequency and voltage are supplied only at
the proper governed speed. Some connected
electrical load devices may be damaged by incor­rect frequency and/or voltage. Only qualified
service technicians should adjust the governed
speed.

K

Section 4 — Maintenance

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

OIL DIPSTIC

16 Generac®Power Systems, Inc.

CHANGING ENGINE OIL

Refer to maintenance performed by authorized service
facilities for engine oil and filter change frequencies.

Drain the oil while the engine is still warm from run­ning. This means warm up the engine, shut it down and
drain immediately as follows:

1. Remove OIL DRAIN HOSE from its retaining clip.

2. Loosen and remove OIL DRAIN HOSE CAP. Drain
oil completely into suitable container.

3. When all oil has drained, install and tighten OIL
DRAIN HOSE CAP, and re-install into its retaining
clip.

4. Turn OIL FILTER (Figure 4.3) counterclockwise and
remove. Dispose of old filter.

Figure 4.3 - Oil Filter

5. Apply light coating of new engine oil to seal of new
oil filter. Install FILTER and tighten by hand only.
DO NOT OVERTIGHTEN.

6. Remove OIL FILL CAP. Add recommended oil (see
SPECIFICATIONS). DO NOT FILL ABOVE THE DIP­STICK “FULL” MARK. Crankcase oil capacity is 4.0
U.S. quarts (3.8 liters).

After refilling the crankcase with oil, always
check oil level on dipstick. NEVER OPERATE
ENGINE WITH OIL BELOW THE DIPSTICK “ADD”
MARK.

7. Start engine and check for oil leaks.

CHANGING THE ENGINE AIR CLEANER

To replace the engine air cleaner, (part number 59402),
simply remove the air cleaner cover and replace the air
filter making sure it is positioned properly before reat­taching the cover (Figure 4.4).

Figure 4.4 – Engine Air Cleaner

See the “Service Schedule,” Section 6, for air cleaner
maintenance.

SPARK PLUGS

Reset the spark plug gap or replace the spark plugs as
necessary. See Section 6.

1. Clean the area around the base of the spark plugs to
keep dirt and debris out of the engine. Clean by
scraping or washing using a wire brush and com­mercial solvent. Do not blast the spark plugs to
clean.

2. Remove the spark plugs and check the condition.
Replace the spark plugs if worn or if reuse is ques­tionable. See the “Service Schedule,” Section 6, for
recommended inspection.

3. Check the spark plug gap using a wire feeler gauge.
Adjust the gap to 0.5-0.6 mm (0.020-0.025 inch) by
carefully bending the ground electrode (Figure 4.5).

Figure 4.5 – Setting the Spark Plug Gap

COOLANT CHANGE

Every year, have Authorized Service Facility drain, flush
and refill the cooling system. See SPECIFICATIONS
(page 8) for cooling system recommendations.

Section 4 — Maintenance

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

SET PLUG GAP AT 0.5-0.6 mm

(0.020-0.025 inch)

OIL FILTER