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General Motors Vortec 4.3L Engine

The General Motors Vortec 4.3L is a 4.3 L 6-cylinder natural aspiration engine rated at 1800 rpm, producing up to 56 kW. It powers generator sets from Kohler, SDMO and Winco, including the 30RZG, 35RZ, 38RCL and 40ERES. It holds 4.3 L (1.1 gal) of oil and 15 L (4.0 gal) of coolant.

Also known as: General Motors Vortec 4.3L

4.3 L

Displacement

Cylinders

1800 rpm

Rated speed

56 kW

Gross power

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

Engine specifications

Oil capacity	4.3 L
Coolant capacity	15.0 L
Displacement	4.3 L
Cylinders	6
Aspiration	Natural Aspiration
Rated speed	1800 rpm
Gross power	56 kW

Generator sets powered by this engine

Shared across brands: Kohler, SDMO, Winco

Kohler 30RZG Kohler 35RZ Kohler 38RCL Kohler 40ERES Kohler 40REZG Kohler 45ERES Kohler 45REZG SDMO G 40 SDMO G45 Winco PSS40-17 Winco PSS40-18 Winco PSS40-3 Winco PSS40-4

Common problems

The generator set cranks but does not start, starts hard, lacks power, or operates erratically
Cause: Air cleaner clogged
Fix: Clean and/or replace the air cleaner.
Generator set stops suddenly
Cause: Low oil pressure shutdown
Fix: Check for oil leaks. Check the oil level and add oil if necessary.
The generator set does not crank
Cause: Battery weak or dead
Fix: Recharge or replace the battery.
No AC output
Cause: AC circuit breaker in the OFF position
Fix: Place the circuit breaker in the ON position.
Loss of communication to accessory modules
Cause: Bad connections
Fix: Check wiring and connections. Verify that cable size and length of run comply with the instructions in the Installation manual.
LCM relays do not operate
Cause: Bad connections
Fix: Check wiring and connections. Verify that cable size and length of run comply with the instructions in the Installation manual.
Low output or excessive drop in voltage
Cause: Generator set overloaded
Fix: Reduce the load.
Fuse M3, battery charging alternator, 70 amps M3
Fuse F6, starter, 20 amps F6
Fuse F4, ignition, 15 amps F4
Fuse F2, ECM 10 amps F2
Fuse F1, 5 amps F1
Fans run after engine shuts down
Cause: The fans continue to run for 2 minutes after the engine shuts down to evacuate the engine compartment.
Date is flashing
Cause: Controller power was disconnected and then reconnected
Fix: Check battery connections. See Figure 5-1. Check utility power connection for the built-in battery charger. Reset the time, date, and exercise schedule. See Section 2.5.7, Setting the Exerciser at Power-Up.
Controller LCD display is off
Cause: Low or no battery voltage
Fix: Check connections. Check generator set battery. See Figure 5-1.

Compiled from service & troubleshooting documentation across every generator set that uses the General Motors Vortec 4.3L.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	4.3L		—	1000 hr
Fuel filter	4.3L		—	1000 hr
Oil filter	Filter, oil		GM28351		Amazon eBay $19.46 NAPA $9.09
Battery	12VDC		—	1000 hr
Belt	Serpentine belt system with spring-loaded tensioner		GM16132		Amazon eBay $86.00
Coolant	4.3L	6.8 L	—	1000 hr
Oil	4.3L	5.7 L	—	1000 hr
Spark plug	Spark plug		GM16531		Amazon eBay $8.08 NAPA $5.38

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
Engine oil level	Check	24 hr		Check the oil level in the crankcase every 24 hours of operation or before the engine is started each day
Air cleaner element	Inspect	100 hr
Change engine oil and filter	Change	100 hr
Check all bolts and nuts for tightness	Check	100 hr
Air cleaner element	Replace	1000 hr
Belts and belt tension	Check	1000 hr
Engine coolant	Replace	5000 hr	60 mo	When long-life coolant used
Check coolant level	Check		0 mo
Check engine oil level	Check		0 mo
Check for fluid leaks	Check		0 mo

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	0.51	mm (0.02 in.)
Gap	Spark plug gap	0.7--0.8	mm (0.028--0.030 in.)
Gap	Spark plug gap	0.76	mm (0.03 in.)
Gap	Spark plug gap	0.8--0.9	mm (0.03--0.04 in.)
Gap	Spark plug gap	0.89	mm (0.035 in.)
Gap	Spark plug gap	0.9--1.0	mm (0.036--0.04 in.)
Other	10 in. weld flange bolt circle diameter B	361.95	mm (14.25 in.)
Other	10 in. weld flange outside diameter C	406.4	mm (16.0 in.)
Other	10 in. weld flange quantity of bolts / bolt hole diameter D	12, 25.40	mm (1.00 in.)
Other	12 in. weld flange bolt circle diameter B	431.80	mm (17.00 in.)
Other	12 in. weld flange outside diameter C	482.6	mm (19.0 in.)
Other	12 in. weld flange quantity of bolts / bolt hole diameter D	12, 25.40	mm (1.00 in.)
Other	14 in. weld flange bolt circle diameter B	476.25	mm (18.75 in.)
Other	14 in. weld flange outside diameter C	533.4	mm (21.0 in.)
Other	14 in. weld flange quantity of bolts / bolt hole diameter D	12, 28.58	mm (1.13 in.)
Other	16 in. weld flange bolt circle diameter B	539.75	mm (21.25 in.)
Other	16 in. weld flange outside diameter C	596.9	mm (23.5 in.)
Other	16 in. weld flange quantity of bolts / bolt hole diameter D	16, 28.58	mm (1.13 in.)
Other	18 in. weld flange bolt circle diameter B	577.85	mm (22.75 in.)
Other	18 in. weld flange outside diameter C	635.0	mm (25.0 in.)
Other	18 in. weld flange quantity of bolts / bolt hole diameter D	16, 31.75	mm (1.25 in.)
Other	20 in. weld flange bolt circle diameter B	635.00	mm (25.00 in.)
Other	20 in. weld flange outside diameter C	698.5	mm (27.5 in.)
Other	20 in. weld flange quantity of bolts / bolt hole diameter D	20, 31.75	mm (1.25 in.)
Other	5 in. weld flange bolt circle diameter B	215.90	mm (8.50 in.)
Other	5 in. weld flange outside diameter C	241.30	mm (9.50 in.)
Other	5 in. weld flange quantity of bolts / bolt hole diameter D	8, 22.23	mm (0.88 in.)
Other	6 in. weld flange bolt circle diameter B	254.0	mm (10.0 in.)
Other	6 in. weld flange outside diameter C	279.4	mm (11.0 in.)
Other	6 in. weld flange quantity of bolts / bolt hole diameter D	8, 22.23	mm (0.88 in.)
Other	8 in. weld flange bolt circle diameter B	298.45	mm (11.75 in.)
Other	8 in. weld flange outside diameter C	342.9	mm (13.5 in.)
Other	8 in. weld flange quantity of bolts / bolt hole diameter D	8, 22.23	mm (0.88 in.)
Other	Weld flange angle A (10, 12, 14 in. nominal pipe size)	30	deg.
Other	Weld flange angle A (16, 18, 20 in. nominal pipe size)	22.5	deg.
Other	Weld flange angle A (5, 6, 8 in. nominal pipe size)	45	deg.
Temperature	Block heater thermostat cut-off temperature	27--38	°C	coolant temperature
Temperature	Block heater thermostat cut-off temperature	80--100	°F	coolant temperature
Torque	1-12 fastener	283.0 (209)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	1-8 fastener	259.0 (191)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	1/2-13 fastener	60.0 (44)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	1/2-20 fastener	66.0 (49)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	1/4-20 fastener	6.8 (60)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	1/4-28 fastener	8.1 (72)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	10-24 fastener	2.9 (26)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	10-32 fastener	2.9 (26)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	3/4-10 fastener	199.0 (147)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	3/4-16 fastener	222.0 (164)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	3/8-16 fastener	24.0 (18)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	3/8-24 fastener	27.0 (20)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	5/16-18 fastener	13.6 (120)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	5/16-24 fastener	14.9 (132)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	5/8-11 fastener	113.0 (83)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	5/8-18 fastener	128.0 (94)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	7/16-14 fastener	39.0 (29)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	7/16-20 fastener	43.0 (32)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	8-32 fastener	1.8 (16)	Nm (in. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	9/16-12 fastener	81.0 (60)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	9/16-18 fastener	91.0 (67)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 2 or 5
Torque	M10 x 1.25 fastener	31.0 (23)	Nm (ft. lb.)	Assembled into cast iron or steel, Grade 5.8 or 8.8

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% ethylene glycol			0.6 L	Provides freezing protection to --37_C (--34_F) and overheating protection to 129_C (265_F). Do not use alcohol or methanol antifreeze. Coolant added after block heater installation is approximately 0.6 L (0.2 gal).
Coolant	Long-life coolant				Change interval 5000 hours or 5 years when long-life coolant used; do not mix coolant types
Engine oil	SAE 5W-30	API Starburst (for gasoline engines)	below -18°C	4.7 L	For below -18C (0F)
Engine oil	SAE 10W-30	API Starburst (for gasoline engines)	above -18°C	4.7 L	For -18C (0F) and above; CC/CD classification and straight-weight industrial/stationary oils not acceptable

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
AC Sens Lost	AC Sensing Lost	In Auto mode, generator output AC sensing is lost; starts 10 seconds after crank disconnect. Warning after 1 second if no output detected after crank disconnect; shutdown after 3 seconds if voltage was present and then lost.	Warning	Contact an authorized distributor/dealer for service.
Accy PwrOver	Accessory Power Overload	Over current fault on the accessory controller power output	Warning
Accy PwrOver Warning	Accessory Power Overload	An over current fault (short circuit) on the accessory controller power output.	Warning	Contact an authorized distributor/dealer for service.
Alt Protect Shtdwn	Alternator Protection Shutdown	High generator current detected; shuts down to protect alternator windings from overheating (38RCL only).	Shutdown	Reduce the load.
ATS Com Error	ATS Communication Error	Warning is displayed if RXT interface connection is lost.	Warning	Check communication wiring between transfer switch interface board and generator set.
ATS PhaseRot	ATS Phase Rotation Mismatch	Transfer switch phase rotation does not match; ATS will not transfer.	Warning	Correct the ATS connection per the ATS Installation manual, wiring diagrams, and labels on the transfer switch.
Aux Input	Auxiliary Input	An optional customer-connected input is closed (digital input from optional PIM).	Shutdown	Check customer-supplied equipment.
Batt Chg Flt	Battery Charger Fault	Input to PIM from an external battery charger (not the built-in charger).	Warning	Check external battery charger.
Battery Voltage High	Battery Voltage High	Engine starting battery voltage rises above 125% of the battery voltage setting for more than 10 seconds; inhibited during crank cycle.	Warning	Check the battery rating and condition; check the battery charger operation.
Battery Voltage Low	Battery Voltage Low	Engine starting battery voltage falls below the battery voltage setting (typically 12.5 volts) for more than 90 seconds when engine not running; inhibited during crank cycle.	Warning	Check the battery rating and condition; check the battery charger operation; charge or replace the battery.
CAN comm fault	CAN Communications Fault	Engine CAN communications fault.	Shutdown	Check wiring to ECM; check power to ECM.
Engine Coolant Temperature High	Engine Coolant Temperature High	Engine coolant temperature exceeds the maximum temperature for more than 5 seconds; active after crank disconnect.	Shutdown	Check for blocked air inlets and exhaust outlets.
Engine Oil Pressure Low	Engine Oil Pressure Low	Engine ECM indicates low oil pressure for more than 5 seconds; active 30 seconds after crank disconnect.	Shutdown	Check for leaks in the lubrication system; check the oil level and add oil if low.
EngineSpeed High	Engine Speed High	Engine speed exceeds 115% of normal running speed for more than 0.3 seconds.	Shutdown	Contact an authorized distributor/dealer for service.
EngineSpeed Low	Engine Speed Low	Engine speed drops below 85% of normal running speed for more than 3 seconds.	Shutdown	Reduce the load; contact an authorized distributor/dealer for service.
Exer Not Sch	Exercise Not Scheduled	No exercise has been scheduled on the RDC2 controller.	Warning	See exerciser setup instructions.
Generator Frequency High	Generator Frequency High	Governed frequency exceeds 110% of the system's frequency setpoint for more than 10 seconds; active 10 seconds after engine start.	Shutdown	Contact an authorized distributor/dealer for service.
Generator Frequency Low	Generator Frequency Low	Governed frequency falls below 90% of system frequency setting for more than 10 seconds, or 1 Hz below setting for more than 60 seconds; active 10 seconds after engine start.	Shutdown	Reduce the load and restart the generator set; contact an authorized distributor/dealer for service.
Generator VoltageL1-L2 High	Generator Voltage High	Output voltage exceeds 120% of the system nominal voltage for more than 2 seconds.	Shutdown	Contact an authorized distributor/dealer for service.
Generator VoltageL1-L2 Low	Generator Voltage Low	Output voltage falls below 80% of the nominal system voltage for more than 10 seconds.	Shutdown	Reduce the load and restart the generator set; contact an authorized distributor/dealer for service.
Lo Crank Vlt	Low Cranking Voltage	Battery voltage falls below 60% of system battery voltage for more than 6 seconds while the starter is engaged.	Warning	Charge or replace the battery.
Locked Rotor	Locked Rotor	No engine rotation is sensed during cranking; shuts down 3 seconds after the fault is detected.	Shutdown	Check the battery; check for loose connections; contact an authorized distributor/dealer for service.
MainPwrOverL Shutdown	Main Power Overload	An over current fault on the controller power output (short circuit).	Shutdown	Contact an authorized distributor/dealer for service.
Not in Auto	Not in Automatic Mode	The generator set is not in Automatic (standby) mode; remote start/stop commands from a transfer switch or remote switch will be ignored.	Warning	Press AUTO to place the generator set in Automatic mode, when appropriate.
Over Crank	Over Crank	Three unsuccessful starting attempts.	Shutdown	Check the fuel supply, spark plug, and battery; check for loose connections; contact an authorized distributor/dealer for service.
Speed Sensor Fault	Speed Sensor Fault	Engine speed sensor has failed or engine stalled.	Shutdown	Contact an authorized distributor/dealer for service.
Total Power High ShtDwn	Total Power High Shutdown	Measured load is greater than 102% of the generator set power rating for more than 1 minute (38RCL only).	Shutdown	Reduce the load.

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

Procedures

RDC2 Voltage Calibration Using SiteTech adjustment

Tools: digital voltmeter, personal computer, SiteTech software

Connect PC to controller via USB
With generator off, connect multimeter across L1/L2 (AC volts)
Start generator set
Compare voltmeter reading to controller display
Calculate new Genset Calibration Factor Voltage using (Vmeter / Vcontrol) x Fold = Fnew
Enter new value into SiteTech and click Apply Changes
Verify voltmeter matches controller display
Repeat for L2-L3 and L3-L1 if three-phase
Press OFF to stop generator set

RDC2 Voltage Calibration Using the Controller Keypad adjustment

Tools: digital voltmeter

With generator off, connect digital multimeter across L1 and L2, set to AC volts
Start generator set with RUN button
Navigate to Generator Metering menu, press Select; Volts L1-L2 displayed
Press Select; voltage number flashes
Use up/down arrows to match voltmeter reading
Press Select to confirm
Step to Return screen
Press OFF to stop generator set

VSC Current (Load) Calibration Using the Controller Keypad adjustment

Tools: clamp-on DC current probe or DC current meter

Connect DC current probe/clamp meter to measure generator current
Start generator with RUN button
Adjust system voltage to obtain rated current output with battery bank attached (or use load bank)
Trip output breaker
Navigate to Generator Metering menu, select Generator Load
Press and hold Select for No-Load Calibration; verify breaker open, confirm Yes
Close output breaker; verify rated output current, confirm Yes
Verify displayed load is correct; recalibrate if necessary
Press OFF to stop generator set

Obtain DC2 Controller Password and Serial Number diagnostic

Press OFF and verify that the generator set is not running.
Press and hold the Exercise button until Press Again to Reset OnCue Plus PW is displayed.
Release the Exercise button and press it again within 5 seconds.
Write down the serial number (S/N) and password.

Obtain RDC/DC Controller Password diagnostic

Press OFF to place the controller into OFF mode.
Press the down arrow button (RDC) or exercise button (DC) 5 times.
Note the four-digit code displayed on the controller; this is the controller password.
Write down the password and press OFF to clear the display.

Obtain RDC2 or VSC Controller Password and Serial Number diagnostic

Press the controller down arrow button to navigate to the Networking Information menu.
Follow the reset password procedure shown in Figure 1-3.
Write down the serial number (S/N) and password displayed for 10 seconds.

Power Cycle the Controller diagnostic

Disconnect all input power for two minutes to allow capacitors to discharge.
Remove the battery negative cable or disconnect P1 from the back of the controller.
Disconnect the battery charger 120 VAC input power supply or disconnect P5 from the back of the controller.
Unplug the USB mini-B connector from the front of the controller if plugged in.
Wait two minutes, then reconnect power, hooking up battery power (P1) first.

Procedure to Reset the Controller after a Fault Shutdown diagnostic

⚠ Always identify and correct the cause of a fault shutdown before resetting the controller.

Press the Select button to go to the Overview menu.
Press Select again to display the active fault.
Press Select; Confirm Clear Fault: NO is displayed.
Press the Up arrow button; Confirm Clear Fault: YES is displayed.
Press the Select button to enter YES and clear the fault.
Press the Select button to return to the overview menu.
Press AUTO to put the generator set into automatic mode.

Use Telnet to Check Server Connection diagnostic

Tools: Command prompt, Telnet Client

Activate Telnet Client on the computer if necessary.
Open a command prompt window.
Enter telnet devices.kohler.com 5253.
Successful connection displays the symbols shown in Figure 3-8.

Common Hardware Application installation

Determine entry hole type: round or slotted.
Determine exit hole type: fixed female thread (weld nut), round, or slotted.
For round and slotted exit holes, determine if hardware is greater than 1/2 inch in diameter.
Hardware greater than 1/2 inch in diameter uses a standard nut and SAE washer.
Hardware 1/2 inch or less in diameter can use a properly torqued whiz nut or spiralock nut.
Always use a washer between hardware and a slot.
Always use a washer under a nut.
Use a washer under a bolt when the female thread is fixed (weld nut).

Connect OnCue Plus for RDC/DC installation

Install the Ethernet option board on the generator set controller. See TT-1566.
Connect a network cable from the Ethernet board to your router or modem.

Connect OnCue Plus for RDC2/DC2/VSC installation

Set the controller password before connecting the generator set Ethernet cable to the router.
Connect the RJ45 inline connector included in the OnCue Plus kit to the Ethernet cable inside the generator enclosure.
Connect one end of the customer-provided network cable to the RJ45 connector.
Connect the other end of the network cable to the customer router or modem.

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
		12-Lead		Alternator Reconnections diagram ADV-5875B-M (page 16)
		12-lead optional voltage connections	12	Alternator optional feature
		4-Lead		Alternator Reconnections diagram ADV-5875A-M (page 15)
		4-lead dedicated voltages	4	Alternator standard feature
		Alternator Reconnection drawing ADV-5875U--1	4	4--Lead
100/200	1	Single
100/200	3	Delta
110/127/139/240/254/277	single-phase	switchable		Towable generator model specifications; some models n/a
110/220	1	Single
110/220	3	Delta
115/230	1	Single
120	1	Single		Genset System Voltage/Frequency/Phase table for controller setup
120/208	3	Wye
120/240	1	Single
120/240	3	Delta
127/220	3	Wye
208/220/240/415/440/480	3-phase	reconnectable		Towable generator model specifications
208/220/240/415/440/480	3-phase	switchable		Towable generator model specifications
220	1	Single
220/380	3	Wye
230	1	Single
230/400	3	Wye
240	1	Single
240/416	3	Wye
277/480	3	Wye

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 General Motors Vortec 4.3L?

The General Motors Vortec 4.3L engine has an oil capacity of 4.3 liters.

What is the displacement of the General Motors Vortec 4.3L?

The General Motors Vortec 4.3L has a displacement of 4.3 liters with 6 cylinders.

Which generators use the General Motors Vortec 4.3L engine?

The General Motors Vortec 4.3L powers 13 generator set(s), including Kohler 30RZG, Kohler 35RZ, Kohler 38RCL, Kohler 40ERES, Kohler 40REZG.

How often should you change the oil in the General Motors Vortec 4.3L?

The General Motors Vortec 4.3L oil change interval is every 1000 hours.

What is a common problem with the General Motors Vortec 4.3L engine?

A commonly reported issue on generators using the General Motors Vortec 4.3L is: The generator set cranks but does not start, starts hard, lacks power, or operates erratically. Cause: Air cleaner clogged. Fix: Clean and/or replace the air cleaner..