Facts About Generators
GeneratorsDirectoryCompareRepairEnginesControllersPartsManufacturersGuides
Search models or part #
Home›Engines›Cummins/Onan LSG-423 (Turbocharged)

Cummins/Onan LSG-423 (Turbocharged) Engine

The Cummins/Onan LSG-423 (Turbocharged) is a 4-cylinder turbocharged engine. It powers generator sets from Cummins/Onan, including the 10 GEAD, 20 GEAE and 25 GEAF. It holds 1.15 L (0.3 gal) of oil and 1.15 L (0.3 gal) of coolant.

Also known as: Onan Modified Ford LSG-423 (Turbocharged)

4
Cylinders
1.15 L
Oil capacity
On this pageSpecsGenerator setsMaintenanceFAQ

Engine specifications

Oil capacity1.15 L
Coolant capacity1.15 L
Cylinders4
AspirationTurbocharged

Common problems

15
  • The engine does not start after three full cranking cycles.
    Fix: Place the Run-Stop-Remote switch in the STOP position and momentarily depress the Reset switch. Wait two minutes for the starter motor to cool and then repeat the starting procedure.
  • The engine does not run after a second attempt at starting.
    Fix: Refer to the Troubleshooting section.
  • PRE HET/LOP lamp lights. Engine continues to operate. PRE HET/LOP
    Cause: Engine has begun to overheat and engine temperature has risen to approximately 205°F (97°C) or coolant level is low.
    Fix: A. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. 2B. Indicates engine oil pressure has dropped to 30 psi (207 kPa). If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 4. If engine can be stopped follow procedure in Steps 3 and 4.
  • Hl ENG TEMP lamp lights. Engine shuts down. ENG TEMP
    Cause: Engine has overheated (engine temperature has risen above 215°F/102°C) or coolant level is low.
    Fix: A. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Check for obstructions to cooling airflow and correct as necessary. c. Check for a slipping fan belt and tighten if loose. d. Reset control and restart after locating and correcting problem. Contact an authorized service center if none of the above.
  • Green RUN lamp lights following engine startup.
    Fix: Indicates all engine systems are normal. No corrective action required.
  • Engine runs, shuts down, and LO OIL PRES lamp lights. LO OIL PRES
    Fix: B. Check for dirty fuel filter and replace if necessary (see Maintenance section). c. Check for dirty or plugged air filter and replace if necessary (see Maintenance section). d. Reset the control and restart after correcting the problem. Contact an authorized service center for service if none of the above.
  • 9. The OVERLOAD lamp lights. Engine shuts down. OVERLOAD
    Fix: The line circuit breaker is located in the ATS or generator set output box. If load exceeds generator current rating, the breaker will trip preventing the generator from being overloaded. Locate the source of overload and correct as necessary. Manually reset breaker to reconnect the load to the generator.
  • 8. LO FUEL lamp lights. Engine continues to run....Or to a propane fuel supply (if not already connected). LO FUEL
    Fix: Move the selector switch on the governor mounting LO FUEL lamp lights. Engine shuts down and LO OIL PRES lamp lights.
  • 7. SWITCH OFF lamp flashes. SWITCH OFF
    Fix: Indicates Run/Stop/Remote switch is in the Stop position which will prevent automatic starting if an automatic transfer switch is used. Move the Run/Stop/Remote switch to the Remote position for automatic starting.
  • 6. Engine runs and then shuts down, OVERSPEED lamp lights. OVERSPEED
    Fix: Indicates engine has exceeded normal operating speed. Contact an authorized service center for service.
  • 5. OVERCRANK lamp lights and engine stops cranking. OVERCRANK
    Fix: A. Check for empty fuel tank (LPG Vapor), fuel or leaks, or plugged fuel lines and correct as required.
  • 4, LO OIL PRES lamp lights. Engine shuts down. LO OIL PRES
    Fix: NOTE: See also step 5. a. Check oil level, lines and filters. If oil system is OK but oil level is low, replenish. Reset control and restart. Contact an authorized service center if oil pressure is not in the range of 40 to 65 psi (275 to 448 kPa).
  • 11. Fault lamp lights but no fault exists.
    Cause: The monitor board or a sensor may be at fault.
    Fix: Contact an authorized service center for service.
  • 10. The O/U VOLTAGE lamp lights. Engine shuts down. O/U VOLTAGE
    Fix: Contact an authorized service center for service.
  • The OVERLOAD lamp lights. Engine shuts down.
    Fix: Locate the source of overload and correct as necessary. Manually reset breaker to reconnect the load to the generator.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan LSG-423 (Turbocharged).

Maintenance schedule

ItemSpecCapacityPart #Interval
Air filterCheck or Replace Spark Plugs xX, Check Air Cleaner xX, Check Drive Belt Tension x2, Clean Crankcase Breather x, Check Radiator Hoses for Wear & Cracks x3, Check Fuel Lines and Fittings for Leaks X, Clean Cooling System x4 x4 x4 x4—90 hr
Fuel filterCheck for dirty fuel filter and replace if necessary (see Maintenance section).—
Oil filterChange Crankcase Oil and Filter xs—200 hr
BatteryCheck the battery connections to make sure they are clean and tight. A light coating of non-conductive grease will retard terminal corrosion.—
BeltAn improperly adjusted fan belt can cause engine overheating and insufficient battery charging. Push on the fan belt in the middle and check that it deflects no more than 0.5 in. (13 mm) under a load of 15 lbs. (67 N). If belt is loose, loosen the two bolts on the battery charging alternator and adjust until proper tension is obtained. Retighten alternator bolts after adjustment.—
Coolant filter—
OilCheck the engine oil level during engine shutdown periods at the intervals specified in the Maintenance Table. The dipstick is stamped with FULL and ADD to indicate the level of oil in the crankcase. For accurate readings, shut off the engine and wait approximately 10 minutes before checking the engine oil level.—
Spark plugCheck or Replace Spark Plugs xX—90 hr

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

Common questions

What is the oil capacity of the Cummins/Onan LSG-423 (Turbocharged)?

The Cummins/Onan LSG-423 (Turbocharged) engine has an oil capacity of 1.15 liters.

Which generators use the Cummins/Onan LSG-423 (Turbocharged) engine?

The Cummins/Onan LSG-423 (Turbocharged) powers 3 generator set(s), including Cummins/Onan 10 GEAD, Cummins/Onan 20 GEAE, Cummins/Onan 25 GEAF.

What is a common problem with the Cummins/Onan LSG-423 (Turbocharged) engine?

A commonly reported issue on generators using the Cummins/Onan LSG-423 (Turbocharged) is: The engine does not start after three full cranking cycles.. Fix: Place the Run-Stop-Remote switch in the STOP position and momentarily depress the Reset switch. Wait two minutes for the starter motor to cool and then repeat the starting procedure..