4.5 L NA Engine

The 4.5 L NA is a 4.5 L 4-cylinder naturally aspirated engine rated at 1800 rpm. It powers generator sets from Generac, including the XG03245, XG04045 and XG04845. It holds 11 L (2.9 gal) of oil and 11 L (2.9 gal) of coolant.

Also known as: 4.5 L NA

4.5 L

Displacement

Cylinders

1800 rpm

Rated speed

11.0 L

Oil capacity

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Oil capacity	11.0 L
Coolant capacity	11.0 L
Displacement	4.5 L
Cylinders	4
Aspiration	Naturally aspirated
Rated speed	1800 rpm

Generator sets powered by this engine

Generac XG03245 Generac XG04045 Generac XG04845

Common problems

Overspeed shutdown. Overspeed shutdown.
Fix: Check governor and throttle linkages for freedom of movement. Check overspeed switch.
Overspeed light on, no shutdown. Overspeed light on, no shutdown.
Fix: Disconnect wire at TB11-29. Light on after reset; replace engine monitor board.
Overcrank fault lamp lights and engine stops cranking after approximately 75-seconds. Overcrank fault lamp lights and engine stops cranking after approximately 75-seconds.
Fix: See engine service manual for troubleshooting fuel system. After correcting fault, reset engine monitor relay by placing Run-Stop/Reset-Remote switch to Stop/Reset position, depressing Reset button, then to the required running position.
Loss of life. W000209
Fault lamp lights, no fault exists. Fault lamp lights, no fault exists.
Fix: To check a no-fault condition, disconnect leads from T B I l terminals 29, 30 and 31. If fault lamp lights with leads disconnected, replace engine monitor board. Reconnect leads.
Fault lamp lights immediately after engine starts. Fault lamp lights immediately after engine starts.
Fix: Check for: Overspeed condition as engine starts.
Fault lamp lights and engine shuts down after running for a period. Fault lamp lights and engine shuts down after running for a period.
Fix: A. Oil level. Engine will shut down if sensor is closed. b. Check engine manual for troubleshooting oil system. c. High engine temperature. Check coolant level; check water flow (city water cooled systems); check radiator for free air flow, and fan belts for tightness. See engine manual for troubleshooting cooling system. d. Check for faulty oil pressure sensor or faulty high engine temperature sensor.
Engine stops cranking and fault lamp lights, after cranking approximately 75 seconds. Engine stops cranking and fault lamp lights, after cranking approximately 75 seconds.
Fix: See engine service manual for troubleshooting fuel system. After correcting problem, reset engine monitor relay by placing Run-Stop/Reset-Remote switch to Stop/Reset, then back to the required running position.
Engine runs, shuts down, cranks for 75-seconds, cranking cycle stops, overcrank light ON. Engine runs, shuts down, cranks for 75-seconds, cranking cycle stops, overcrank light ON.
Fix: Check fuel supply.
Engine runs, shuts down and cranks for 75-seconds. Cranking cycle stops; fault lamp lights. Engine runs, shuts down and cranks for 75-seconds. Cranking cycle stops; fault lamp lights.
Fix: Check fuel supply.
Do not open or mutilate batteries. Batteries contain electrolyte solution which can cause burns and blindness. If electrolyte contacts skin or eyes, flush with water and seek immediate medical attention. W000163
Do not alter construction of, installation, or block ventilation for generator. Failure to do so could result in unsafe operation or damage to the generator. W000146
*Low oil pressure shutdown. Low oil pressure shutdown.
Fix: A. Oil level. Replenish if necessary. b. Sensor. Faulty sensor will shut down engine. c. Refer to engine service manual for troubleshooting guide for oil system.
*Low oil pressure light ON. No shutdown. Low oil pressure light ON. No shutdown.
Fix: Disconnect wire at TB11-30. Light ON after relay reset. Replace engine monitor board.
*High engine temperature shutdown. High engine temperature shutdown.
Fix: A. Coolant level. Replenish if necessary. b. City water cooled sets. Check water flow, valves, etc. c. Check sensor; check thermostat. d. Radiator model, check fan belts, radiator for obstructions, etc.

Compiled from service & troubleshooting documentation across every generator set that uses the 4.5 L NA.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			140-1347	150 hr	Amazon eBay $100.60
Oil filter	Full flow spin-on cartridge		—	150 hr
Battery	Group 27 recommended (600 CCA min); Group 31 maximum (750 CCA min); 12 V		—
Belt			—	1000 hr
Coolant	Generac brand 50/50 ethylene glycol type coolant	11.0 L	—	1000 hr
Oil	Generac 5W-20 Synthetic (after 25 hour break-in); factory filled with 5W-20 conventional	11.0 L	—	150 hr
Spark plug	Gap 0.012-0.017 in (0.31-0.45 mm); torque 28 ft-lb (38 Nm)		—	300 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Accessory drive belt	Inspect	1000 hr	24 mo	Schedule C: inspect for wear or damage
Accessory drive belt	Replace	1000 hr		Schedule C
Air filter element	Replace	1000 hr	24 mo	Schedule C
Coolant level and hoses	Inspect	1000 hr	24 mo	Schedule C
Coolant system	Drain	1000 hr	24 mo	Schedule C: drain/flush
Critical fasteners	Adjust	1000 hr		Schedule C: tighten
Enclosure slots and openings	Inspect	1000 hr	24 mo	Schedule C
Fuel hoses	Inspect	1000 hr	24 mo	Schedule C
Lubricating oil and oil filter	Replace	1000 hr	24 mo	First service — Schedule C
Lubricating oil level and drain hose	Inspect	1000 hr	24 mo	Schedule C
Radiator for clogging	Inspect	1000 hr	24 mo	Schedule C
Spark plugs	Replace	1000 hr	24 mo	Schedule C
Battery	Replace		36 mo	Replace battery every three years; every two years in extreme conditions

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Gap	Spark plug gap	0.012-0.017	in (0.31-0.45 mm)
Pressure	LP fuel pressure to regulator	7-14	in H2O (1.74-3.48 kPa)
Pressure	LP vapor fuel supply pressure to fuel shutoff valve	7-14	in H2O (1.74-3.48 kPa)
Pressure	Maximum fuel system pressure drop (static/cranking/no-load/full-load)	1-2	in H2O (0.25-0.50 kPa)
Pressure	NG fuel pressure to regulator	3.5-14	in H2O (0.87-3.48 kPa)
Pressure	NG fuel supply pressure to fuel shutoff valve	3.5-14	in H2O (0.87-3.48 kPa)
Torque	1-phase (1 position) load lug (C, D)	375	in-lbs (42.37 Nm)
Torque	1-phase (1 position) lug	375	in-lbs (42.37 Nm)
Torque	3-phase (1 position) distribution block lug	375	in-lb (42.37 Nm)
Torque	3-phase (2 position) distribution block lug	275	in-lb (31.07 Nm)
Torque	3-phase distribution block S1, S2, S3 lug	120	in-lb (13.6 Nm)
Torque	3-phase distribution block, 1-position lug (A)	375	in-lb (42.37 Nm)
Torque	3-phase distribution block, 2-position lug (B)	275	in-lb (31.07 Nm)
Torque	Frame breaker lug torque (Generac 225 AF 2/3 Pole)	375	in-lb (42.4 Nm)
Torque	Generac 225 AF 2-Pole / 3-Pole frame breaker lug	375	in-lb (42.4 Nm)
Torque	Neutral bonding wire removal nut	200	in-lb (22.6 Nm)	when neutral bonding wire removed
Torque	Neutral/ground bonding nut	200	in-lb (22.6 Nm)	if neutral bonding wire removed
Torque	S1, S2, S3 lug torque (3-phase distribution block)	120	in-lb (13.6 Nm)
Torque	Spark plug	28	ft-lb (38 Nm)
Torque	Voltage Configuration Cartridge (VCC) mounting screws	55	in-lb (6.2 Nm)
Voltage	1-phase circuit breaker terminal to neutral	120	V
Voltage	1-phase circuit breaker terminal to terminal	240	V
Voltage	3-Phase Delta config circuit breaker terminal to terminal (240/120 V VCC)	240	V	E1-E2, E1-E3, E2-E3
Voltage	3-Phase Y config circuit breaker terminal to terminal (208/120 V VCC)	208	V	E1-E2, E1-E3, E2-E3
Voltage	3-Phase Y config circuit breaker terminal to terminal (480/277 V VCC)	480	V	E1-E2, E1-E3, E2-E3

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Coolant	50/50 Ethylene Glycol		below 50°C	11.0 L	Coolant system capacity 2.9 US gal (11 L)
Coolant	50/50 ethylene glycol			11.0 L	Use only Generac brand 50/50 ethylene glycol type coolant. Do not use propylene glycol. Mix ratio 40-60% antifreeze depending on ambient.
Engine oil	5W-20	SAE		11.0 L	Factory filled with 5W-20 conventional; after 25 hour break-in use Generac proprietary 5W-20 Synthetic. Once synthetic is used, use for life. Do not use special additives.
Fuel	Liquid Propane (LP) Vapor or Natural Gas (NG)	LP energy density >= 91,420 BTU/US gal (25.5 MJ/L); NG >= 1,036 BTU/ft3 (37.3 MJ/m3)			LP minimum tank size 250 US gal (946 L) recommended.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

Code	Name	Meaning	Severity	Action
BATTERY PROBLEM	Battery Problem	Yellow LED illuminated in any state.	Warning	Contact an IASD for assistance.
CHARGER MISSING AC	Charger Missing AC	AC input to battery charger circuit missing for greater than 5 minutes during charging cycle.	Warning	Inspect connections at transfer switch, fuses in transfer switch. Contact an IASD for assistance.
CHARGER WARNING	Charger Warning	Yellow LED illuminated in any state.	Warning	Contact an IASD for assistance.
Configuration Mismatch	Configuration Mismatch (3-Phase only)	Unit either shuts down or does not start.	Shutdown	Correct voltage configuration selection in the control panel to match installed VCC. Contact an IASD for assistance.
FUSE PROBLEM	Fuse Problem	Unit will not start in AUTO with utility loss.	Shutdown	Inspect 7.5 amp fuse. Replace with an ATO 7.5 amp fuse if bad; if fuse is good, contact an IASD.
GENERATOR EMERGENCY SHUTDOWN SWITCH	Generator Emergency Shutdown Switch	Unit either shuts down or does not start when one or both switches are OFF (O).	Shutdown	Clear alarm and verify both generator emergency shutdown switches are ON (I).
HIGH TEMPERATURE	High Temperature	Unit shuts down during operation.	Shutdown	Inspect ventilation around generator, intake, exhaust, and rear of generator. If no obstruction, contact an IASD.
INSPECT BATTERY	Inspect Battery	Yellow LED illuminated in any state.	Warning	Inspect battery. Press ENTER to clear.
LOW BATTERY	Low Battery	Yellow LED illuminated in any state.	Warning	Clear alarm. Check battery option in control menu; if GOOD contact an IASD, if CHECK BATTERY replace battery.
LOW OIL PRESSURE	Low Oil Pressure	Unit will not start in AUTO with utility loss.	Shutdown	Check oil level / add oil per owner's manual. If oil level is correct, contact an IASD.
LOW VOLTS REMOVE LOAD	Low Volts Remove Load	Unit will not start in AUTO with utility loss.	Shutdown	Clear alarm and remove household loads. Set to AUTO and restart.
NOT ACTIVATED	Not Activated	Unit will not start in AUTO with utility loss.	Info	See Checking Manual Transfer Switch Operation.
OVERCRANK	Overcrank	Unit will not start in AUTO with utility loss.	Shutdown	Verify fuel line shutoff valve is ON. Clear alarm. Attempt start in MANUAL. If it does not start or runs rough, contact an IASD.
OVERLOAD REMOVE LOAD	Overload Remove Load	Unit shuts down during operation.	Shutdown	Correct voltage configuration selection in the control panel. Clear alarm and remove household loads. Put back in AUTO and restart.
OVERSPEED	Overspeed	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD for assistance.
OVERVOLTAGE	Overvoltage	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD for assistance.
RPM SENSE LOSS	RPM Sense Loss (shutdown)	Unit was running and shuts down, attempts to restart.	Shutdown	Clear alarm and remove household loads. Set to AUTO and restart. If it does not start, contact an IASD.
SERVICE A	Service A	Yellow LED illuminated in any state.	Warning	Perform SERVICE A maintenance. Press ENTER to clear.
SERVICE B	Service B	Yellow LED illuminated in any state.	Warning	Perform SERVICE B maintenance. Press ENTER to clear.
STEPPER OVERCURRENT	Stepper Overcurrent	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD for assistance.
UNDERSPEED	Underspeed	Unit will not start in AUTO with utility loss.	Shutdown	Contact an IASD for assistance.
UNDERVOLTAGE	Undervoltage	Unit will not start in AUTO with utility loss.	Shutdown	Correct voltage configuration selection in the control panel. Contact an IASD for assistance.
WIRING ERROR	Wiring Error	Unit will not start in AUTO with utility loss.	Shutdown	Verify wiring is installed and landed correctly.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Fuel Pressure Test at Startup diagnostic

⚠ Severe valve deformation can occur if gauge probe is left in test port for hours or days.

Tools: Pressure gauge or water manometer, Gauge adapter probe (Part Number 0K2341)

Connect a load bank (or load bank + system load) to bring unit to full rated kW load.
Measure fuel supply pressure at test port at fuel solenoid shutoff valve under static, cranking, no-load, and full-load conditions.
Verify pressure stays within 3.5-14 in H2O (NG) or 7-14 in H2O (LP) and drop does not exceed 1-2 in H2O.
Tighten protective cap on test port to prevent tampering.

Connecting Load Wiring - 1-Phase Models installation

⚠ Turn utility and emergency power OFF before connecting.

Connect load wiring to E1 & E2.
Connect generator neutral to neutral terminal bar.
Connect equipment ground to equipment ground lug.
Tighten 1-phase (1 position) lugs (C) and (D) to 375 in-lb (42.37 Nm).

Connecting Load Wiring - 3-Phase Without a Circuit Breaker installation

Route copper load wires toward end panel; keep separated from factory wiring.
Connect generator neutral to neutral terminal bar (A).
Connect equipment ground to equipment ground lug (B).
Tighten 3-phase 2-position lug (B) to 275 in-lb (31.07 Nm).
Tighten 3-phase 1-position lug (A) to 375 in-lb (42.37 Nm).

Installing the Battery installation

⚠ Explosion. Batteries emit explosive gases. Always connect positive battery cable first to avoid spark. Failure to do so could result in death or serious injury. (W000133)

Loosen nylon strap on battery tray.
Install battery onto tray.
Secure nylon strap over top of battery and tighten.
Install positive battery cable (red) to positive terminal.
Install negative battery cable (black) to negative terminal.

Installing the Voltage Configuration Cartridge (VCC) installation

⚠ Voltage selection installer code required.

Assemble the new VCC (B) over the terminal block (C).
VCC is designed to install one way with the tabs aligned.
Install the five screws to secure the VCC tabs to the terminal block.
Tighten screws to 55 in-lb (6.2 Nm).
Navigate to the 3-phase voltage selection in the controller.
Select the 3-phase voltage matching the installed VCC.
Verify the voltage in the menu.

Cleaning/Gaping/Replacing Spark Plugs maintenance

⚠ Electric shock. Do not disconnect spark plug wires with engine running. Doing so could result in death or serious injury. (W000140)

Tools: spark plug socket, wire feeler gauge, wire brush

Remove negative battery cable.
Remove spark plug cables from terminals.
Clean area around spark plugs.
Remove spark plugs with spark plug socket.
Inspect threads; clean with thread chaser if needed.
Clean spark plugs with wire brush and solvent; do not blast.
Inspect gap with wire feeler gauge; gap 0.012-0.017 in (0.31-0.45 mm).
Adjust gap by bending ground electrode.
Finger tighten spark plugs; tighten to 28 ft-lb (38 Nm) with socket.
Install spark plug cables; verify captured in clips.

Draining and Flushing Coolant System maintenance

⚠ Risk of burns. Allow engine to cool before draining oil or coolant. Failure to do so could result in death or serious injury. (W000139)

Tools: wrenches, container, funnel

Disconnect and empty coolant overflow reservoir.
Rotate and remove plastic cover at top of enclosure.
Slowly unscrew radiator cap.
Locate drain screw at bottom left of radiator; open drain.
Remove coolant drain hose from clamp; remove plug; drain coolant.
Install drain plug and hose; close radiator drain screw.
Fill radiator with de-ionized or distilled water and flushing product; use 2.9 US gal (11 L).
Install radiator cap.
Press MANUAL to start engine; run until thermostat opens.
Inspect hoses for leaks; press OFF; allow engine to cool.
Repeat steps 4-19 to drain.
Add recommended coolant; top off radiator and overflow bottle.

Inspecting Accessory/Drive Belt maintenance

Inspect belt for cracks, fraying, excessive wear, or damage.
Verify belt is free of grease and oil.
Replace belt if contaminated, damaged, frayed, or worn.
Inspect belt and rotating components.

Preparing For Storage maintenance

Tools: wrenches, container

Open viewing window.
Press MANUAL to start engine; blue LED illuminates.
Allow engine to reach normal operating temperature.
Press OFF; red LED illuminates.
Set generator MLCB to OFF (OPEN), if equipped.
Remove 7.5 amp fuse.
Turn off utility power to transfer switch.
Place DO NOT OPERATE tag.
Wait five minutes for engine to cool.
Remove front access panel.
Remove oil drain hose from holding clamp; drain oil.
Install oil drain plug and hose.
Remove oil filter; coat new filter gasket with oil.
Install oil filter; tighten 3/4 to 1 full turn.
Fill engine with recommended oil; install oil fill cap.

Removing Battery maintenance

⚠ Electrical shock. Disconnect battery ground terminal before working on battery or battery wires. Failure to do so could result in death or serious injury. (W000164)

Remove negative battery cable from negative terminal.
Remove positive battery cable from positive terminal.
Install rubber protective cover over positive terminal.
Release buckle on nylon strap securing battery.
Grasp battery strap and lift battery from tray.
Remove rubber protective cover from positive terminal.

Replacing Air Filter Element maintenance

Tools: wrenches

Remove nut and bolt from air filter clamp; loosen elbow clamp.
Remove air filter element and discard.
Clean elbow of dust, dirt, or debris.
Place new air filter element into elbow clamp.
Install elbow clamp and tighten; install nut and bolt; tighten until snug.

Replacing Lubricating Oil and Oil Filter maintenance

⚠ Risk of burns. Allow engine to cool before draining oil or coolant. Failure to do so could result in death or serious injury. (W000139)

Tools: wrenches, container, shop towel

Follow Removing From Service; wait at least 10 minutes.
Remove oil drain hose from holding clamp.
Use two wrenches to remove oil drain plug; drain oil.
Install oil drain plug and hose into holding clamp.
Turn oil filter counterclockwise to remove; wipe adapter.
Apply clean engine oil to gasket of new oil filter.
Install oil filter by hand until gasket contacts; tighten 3/4 to 1 full turn.
Fill engine with 11.6 qt (11 L) recommended oil for 4.5 L NA.
Install oil fill cap.
Connect negative battery cable; install 7.5 amp fuse.
Press MANUAL to start; run one minute; inspect for leaks.
Press OFF; wait 10 minutes; check oil level and add as needed.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
208/120	3 (Y)	3-Phase Alternator Y Configuration, 12 lead	E1, E2, E3, S1-S12	208/120 V VCC installed
208/120 V	3 (Y)	12-lead stator, Y configuration with 208/120 V VCC (factory default)	S1-S12, E1, E2, E3	Rated voltage E1-E2, E1-E3, E2-E3 is 208V; each terminal to neutral (00) is 120V.
240 VAC 1-phase	1	Four-lead stator factory-connected to main circuit breaker	E1, E3, 00 (neutral), 11/22/33/44	Rated voltage between each breaker terminal and neutral (00) is 120V; between breaker terminals is 240V.
240/120	1	Four-Lead 1-Phase Stator	E1, E3, neutral point 00	Rated voltage between each circuit breaker terminal is 240V; between each terminal and neutral point 00 is 120V
240/120	3 (Delta)	3-Phase Alternator Delta Configuration, 12 lead	E1, E2, E3, NB, S1-S12	E2 to NB (high leg) is 208V; E1-00 and E3-NB approx 120V
240/120 V	3 (Delta, high leg)	12-lead stator, Delta configuration with 240/120 V VCC	S1-S12, E1, E2, E3, NB	Rated voltage E1-E2, E1-E3, E2-E3 is 240V; E2-NB (high leg) is 208V; E1-00 and E3-NB approx. 120V.
480/277	3 (Y)	3-Phase Alternator Y Configuration, 12 lead	E1, E2, E3, S1-S12	480/277 V VCC
480/277 V	3 (Y)	12-lead stator, Y configuration with 480/277 V VCC	S1-S12, E1, E2, E3	Rated voltage E1-E2, E1-E3, E2-E3 is 480V; each terminal to neutral (00) is 277V.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

What is the oil capacity of the 4.5 L NA?

The 4.5 L NA engine has an oil capacity of 11.0 liters.

What is the displacement of the 4.5 L NA?

The 4.5 L NA has a displacement of 4.5 liters with 4 cylinders.

Which generators use the 4.5 L NA engine?

The 4.5 L NA powers 3 generator set(s), including Generac XG03245, Generac XG04045, Generac XG04845.

How often should you change the oil in the 4.5 L NA?

The 4.5 L NA oil change interval is every 150 hours.

What is a common problem with the 4.5 L NA engine?

A commonly reported issue on generators using the 4.5 L NA is: Overspeed shutdown.. Fix: Check governor and throttle linkages for freedom of movement. Check overspeed switch..