Home›Engines›GN1850-DG-A3

GN1850-DG-A3 Engine

The GN1850-DG-A3 is an engine. It powers generator sets from Cummins/Onan, including the K1800 and K2100.

Also known as: GN1850-DG-A3

On this pageSpecs Generator sets FAQ Service intervals Torque & specs Fluids Procedures

Engine specifications

Generator sets powered by this engine

Cummins/Onan K1800Cummins/Onan K2100

Common problems

Only slight output voltage is delivered (3 ~ 6V)
Cause: Worn brush or faulty contact surface of slip ring
Fix: Clean brush contact and slip ring, or replace brush
Rated output voltage is not available
Cause: Abnormal load circuit, blown circuit breaker (S.T.D., voltage 10%)
Fix: Remove abnormality in load circuit and replace fuse
Pilot lamp does not light and output voltage is OV
Cause: Faulty contact of receptacles or disconnected wiring inside of control box
Fix: Repair or replace
Output voltage is not delivered
Cause: Disconnected wiring
Fix: Repair or replace stator coil, demagnetization of permanent magnet, clean brush contact and slip ring, repair or replace brush, or repair or replace sub coil
Output voltage is more than S.T.D. voltage by 30%
Cause: Defective AVR
Fix: Replace
Output voltage OV
Fix: Set the switch to the desired AC or DC position
Fluctuation of engine revolution is abnormal
Cause: Disconnected or punctured AVR capacitor, faulty brush contact, excessive initial current, low engine output, faulty engine governor
Fix: Replace capacitor, check for wear, wear amount, and contamination of contacting surface of brush and clean if necessary, repair or replace
Generator set operates on a slight grade, and the fuel tank is completely filled.
Fix: Do not fill completely if the generator set will operate on a slight grade.
Fuel level indicator looks damaged or loose.
Fix: Install a new indicator before starting generator set.
Faulty electrical equipment connected to the generator presents an electrical shock hazard.
Fix: Check all electrical equipment for frayed cords or breaks in the insulation before using. Properly applied and maintained ground fault circuit interrupters can afford additional protection against the hazard of electrical shock.
Crankcase pressure might blow out hot oil and cause serious burns.
Fix: Do not attempt to check oil while the generator set is running. Add oil until it reaches the top of the oil port.

Compiled from service & troubleshooting documentation across every generator set that uses the GN1850-DG-A3.

Service intervals

Item	Action	Hours	Months	Notes
Air cleaner element - restriction	Check	250 hr	6 mo	Replace air cleaner element as required
Air compressor air cleaner element	Replace	250 hr	6 mo	Cummins two-cylinder compressor
All belts	Check	250 hr	6 mo
Belt tension	Check	250 hr	6 mo	Measure in center span of pulleys; fan idler pulley design self-tensions
Belts	Check	250 hr	6 mo	Replace cracked or frayed belts
Coolant filter	Change	250 hr	6 mo	At each oil and filter change interval
Cooling fan	Check	250 hr	6 mo	Check for cracks, loose rivets, bent or loose blades
Cooling system additives (DCA4)	Check	250 hr	6 mo	Check concentration whenever coolant is added between filter changes
Crankcase breather tube/hose	Check	250 hr	6 mo	Remove and check internally for obstructions or sludge; clean or replace
Engine oil	Change	250 hr	6 mo	First service — Whichever occurs first
Engine oil and oil filters	Change	250 hr	6 mo	Whichever occurs first
Fan idler pivot arm	Lubricate	1500 hr	12 mo	Water pump type grease until grease appears
Fuel filter	Replace	250 hr	6 mo	Clean area around fuel filter head first
Hoses	Inspect	1500 hr	12 mo	Check/replace as required
Oil filters	Change	250 hr	6 mo	Change filters with oil
Pulley tensioner	Check	250 hr	6 mo
Batteries	Check	1500 hr	12 mo	Check electrolyte level and state of charge
Cold start aids	Check	1500 hr	12 mo	Seasonal
Crankshaft end clearance	Inspect	1500 hr	12 mo	Measure with dial indicator
Engine (steam clean)	Clean	1500 hr	12 mo	Before conducting any 1500 hour maintenance
Engine mounting bolts and nuts	Check	1500 hr	12 mo	Tighten loose; inspect rubber
Engine protection system	Check	1500 hr	12 mo	Follow manufacturer's recommended procedures
Fan idler pulley tensioner	Adjust	1500 hr	12 mo	Solid control rod engines only; shock absorber engines require no adjustment
Front engine support	Lubricate	1500 hr	12 mo	Lubricate until grease appears at outside of support
Heat exchanger zinc plugs (marine only)	Check	1500 hr	12 mo	Check length of all zinc plugs; replace if 50 percent eroded
Steam clean engine	Clean	1500 hr	12 mo	Before any 1500 hour maintenance
Valves and injectors	Adjust	1500 hr	12 mo	First service — Initial adjustment; then not again before 6000 hour/2 year injector calibration
Air compressor	Inspect	6000 hr	24 mo	Discharge and intake checks
Coolant	Change	6000 hr	24 mo	Clean and flush cooling system
Cooling system	Change	6000 hr	24 mo	Clean system and change antifreeze; whichever comes first
Crankcase breather element	Replace	6000 hr	24 mo	Clean/replace
Engine protection system	Adjust	6000 hr	24 mo	Calibration required
Fan hub	Inspect	6000 hr	24 mo	End clearance and grease leakage
Fan idler pulley assembly	Replace	6000 hr	24 mo	Rebuild or replace as necessary
Fuel pump	Clean	6000 hr	24 mo	Clean and calibrate at a Cummins Authorized Repair Location
Injectors	Clean	6000 hr	24 mo	Clean and calibrate at a Cummins Authorized Repair Location
Thermostats and seals	Replace	6000 hr	24 mo	Discard worn thermostats and seals
Throttle travel/throttle air cylinder	Check	6000 hr	24 mo	Throttle lever breakover 3 to 6 mm
Turbocharger	Inspect	6000 hr	24 mo	Check blades, shaft spin, axial and radial clearance
Vibration damper	Inspect	6000 hr	24 mo	Replace after 24,000 hours; K2000 dampers replaced every 12,000 hours

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
Clearance	Crankshaft end clearance	0.13 MIN / 0.51 MAX	mm
Clearance	Crankshaft end clearance	0.13 to 0.51	mm	engine mounted in unit
Clearance	Crankshaft side clearance	0.02-0.1	mm	reference; allowable limit 0.2 mm
Clearance	Cylinder bore	42.000-42.025	mm	reference; allowable limit 42.2 mm
Clearance	Cylinder bore	60.00-60.02	mm	reference; allowable limit 60.12 mm
Clearance	Cylinder bore	67.000-67.025	mm	reference; allowable limit 67.2 mm
Clearance	Cylinder bore	71.98-72.00	mm	reference; allowable limit 72.2 mm
Clearance	Cylinder bore	73.00-73.02	mm	reference; allowable limit 73.12 mm
Clearance	Cylinder head surface distortion allowable limit	0.4	mm	max; also 0.0157 in
Clearance	Fan hub bearing end clearance	0.03 MIN / 0.15 MAX	mm
Clearance	Fan hub bearing end clearance	0.03 to 0.15	mm
Clearance	Gear backlash	0.023-0.128	mm	reference; allowable limit 0.2 mm
Clearance	Gear backlash	0.029-0.123	mm	reference; allowable limit 0.2 mm
Clearance	Gear backlash	0.03-0.12	mm	reference; allowable limit 0.2 mm
Clearance	Gear backlash	0.033-0.119	mm	reference; allowable limit 0.2 mm
Clearance	Gear backlash	0.033-0.135	mm	reference; allowable limit 0.2 mm
Clearance	Piston pin to connecting rod small-end bore	0.010-0.025	mm	reference; allowable limit 0.1 mm
Clearance	Piston pin to connecting rod small-end bore	0.010-0.033	mm	reference; allowable limit 0.1 mm
Clearance	Piston pin to connecting rod small-end bore	0.015-0.030	mm	reference; allowable limit 0.1 mm
Clearance	Piston pin to connecting rod small-end bore	0.026-0.046	mm	reference; allowable limit 0.08 mm
Clearance	Piston ring gap	0.15-0.35	mm	top/2nd ring; oil ring 0.15-0.35 mm; allowable limit 0.5 mm
Clearance	Piston ring gap	0.2-0.4	mm	top/2nd ring; oil ring 0.2-0.4 mm; allowable limit 0.9 mm
Clearance	Piston ring gap	0.25-0.45	mm	top/2nd ring; oil ring 0.2-0.4 mm; allowable limit 0.9 mm
Clearance	Thermostat seal installation depth	no more than 0.51	mm	below top of cast edge
Clearance	Turbocharger BB (RR-151) and (RR-153) end clearance	0.09 MIN / 0.13 MAX	mm
Clearance	Turbocharger BB bearing radial clearance - RR-151	0.75 MAX	mm	0.030 in
Clearance	Turbocharger BB bearing radial clearance - RR-153	0.55 MAX	mm	0.021 in
Clearance	Turbocharger axial end play - HC5A	0.05 MIN / 0.13 MAX	mm
Clearance	Turbocharger axial end play - HT7100	0.06 MIN / 0.16 MAX	mm
Clearance	Turbocharger axial end play - T18A	0.10 MIN / 0.23 MAX	mm
Clearance	Turbocharger radial clearance compressor impeller - HC5A	0.15 MIN / 0.45 MAX	mm
Clearance	Turbocharger radial clearance turbine wheel - HC5A	0.20 MIN / 0.55 MAX	mm
Clearance	Valve guide clearance exhaust	0.050-0.095	mm	reference; allowable limit 0.1 mm
Clearance	Valve guide clearance intake	0.030-0.067	mm	reference; allowable limit 0.1 mm
Clearance	Valve seat surface width	1.0-1.3	mm	reference; allowable limit 1.5 mm
Clearance	Valve spring free length	30.8-31.3	mm	reference; allowable limit 30.5 mm
Clearance	Valve spring squareness allowable limit	1.5	mm	allowable limit
Gap	Heat exchanger zinc plug erosion limit A	approximately 19	mm	0.75 in; new 51 mm [2 in]
Gap	Heat exchanger zinc plug erosion limit B	approximately 6.4	mm	0.25 in; new 16 mm [0.625 in]
Gap	Spark plug gap	0.0236-0.0276	in	also 0.6-0.7 mm
Gap	Spark plug gap	0.0276	in	also 0.7 mm
Gap	Spark plug gap	0.0354-0.0394	in	also 0.9-1.0 mm
Gap	Spark plug gap	0.0394	in	also 1.0 mm
Other	Air compressor discharge carbon deposit thickness limit	2	mm	1/16 in
Other	Air starting motor minimum air pressure	480	kPa
Other	Alternator belt tension	356	N	Burroughs tension gauge ST-1293
Other	Fan belt tension (20, 22, 24 inch fan center)	2668.9 to 2891.3	N	two pulley fan drive
Other	Fan belt tension verification (28 inch fan center)	2891.3 to 3336.2	N	two pulley fan drive
Other	HVT non-top stop injector travel adjustment	10.234	mm
Other	Maximum intake restriction, clean air filter element	380	mm H2O
Other	Maximum intake restriction, dirty air filter element	635	mm H2O
Other	Maximum vibration damper thickness - Houdaille	66.38	mm	2.574 in
Other	Maximum vibration damper thickness - Made in England Before F-82	65.91	mm	2.595 in
Other	Maximum vibration damper thickness - Made in England F-82 and After	65.66	mm	2.585 in
Other	Minimum cranking speed without starting aid	150	RPM
Other	PTD injector travel limits	7.77 to 7.87	mm
Other	PTD injector travel verification specification	7.80 MIN / 7.82 MAX	mm
Other	PTD non-top stop injector travel adjustment	7.82	mm
Other	PTD non-top stop injector travel limits	7.77 to 7.87	mm
Other	Turbocharger end play - AiResearch T18A	0.10 to 0.23	mm

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	Notes
Coolant	50 percent ethylene glycol / 50 percent water	Low-silicate antifreeze meeting ASTM D4985 (less than .10% silicate)		50/50 gives -34 F freeze point and 228 F boiling point; working range 40 to 60 percent antifreeze; use refractometer, not hydrometer; pre-charge 1.5 SCA units per gallon
Coolant	50/50 low-silicate antifreeze and quality water	ASTM D4985 (less than 0.10% silicate as Na2SiO5)		Must be pre-charged with supplemental coolant additives (DCA4) to 1.5 units per gallon; never below 1.2 or above 3 units per gallon. Do not use soluble oils.
Coolant	60 percent ethylene glycol / 40 percent water	Low-silicate antifreeze	-54°C to -32°C	Arctic specification coolant mixture for -32 to -54 C [-25 to -65 F]
Engine oil	10W30	API type SE, SF class engine oil	below -10°C	below 14°F (-10°C)
Engine oil	SAE 15W-40	API CE or CF4		Cummins Premium Blue or equivalent; CD or CD/SF acceptable where CE/CF4 not available; sulfated ash must not exceed 1.85 mass percent
Engine oil	SAE 5W-30 synthetic CE/SF	API CE or CF4	below -23°C	For ambient temperatures consistently below -23 C [-10 F] with no provision to keep engine warm
Engine oil	SAE #20	API type SE, SF class engine oil	-10°C to 15°C	below 59°F (+15°C)
Engine oil	SAE #30	API type SE, SF class engine oil	above 15°C	above 59°F (+15°C)
Fuel	ASTM No. 2 diesel	No. 2 D; blends of No. 2 D and No. 1 D below 0 C [32 F]		Viscosity must be kept above 1.3 cSt; maximum cloud and pour points 6 C [10 F] lower than ambient
Fuel	Regular automobile gasoline
Grease	Water pump type grease (Amoco Rykon Premium No. 2 / Chevron SRI / Exxon Unirex N2 / Shell Dolium R / Texaco Premium RB)			Fan idler pivot arm and front engine support lubrication

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

Procedures

Adjusting Pilot Screw Opening Degree adjustment

Tools: screwdriver

Tighten pilot screw completely
Loosen according to reference value

Alternator Belt Adjustment adjustment

⚠ Over-tensioning of alternator belts can result in premature accessory drive bushing wear and seal leakage.

Tools: GT-1293 Burroughs Tension Gauge

Loosen the alternator and adjusting link mounting capscrews.
Loosen the jam nuts on the adjusting screw.
Turn the adjusting screw clockwise to tighten the belt tension.
Check the belt tension with a gauge.
Tighten the jam nuts on the adjusting screw to 55 Nm [40 ft-lb].
Tighten the adjusting link and alternator mounting capscrews to 55 Nm [40 ft-lb].
Check the belt tension again.

Checking Valve Clearance adjustment

Tools: feeler gauge

Set piston at top dead center
Measure clearance with feeler gauge
If clearance is under reference value, grind valve stem to adjust

Crossheads - Adjustment adjustment

Tools: ST-669 Torque Wrench Adapter

Adjust the crossheads on the cylinder that has both valves closed.
Loosen the crosshead adjusting screw locknuts on the intake and exhaust valve crossheads.
Turn the adjusting screw out at least one turn.
Hold the crosshead down against its guide.
Turn the adjusting screw in until it touches the top of the valve stem but does not raise the crosshead.
Hold the adjusting screw and tighten the lock nut to the torque value.

Dipstick Calibration adjustment

⚠ The dipstick will break if the scribe mark is too deep.

Tools: scribe

Drain the oil from the pan.
Install the dipstick in the dipstick tube.
Use clean 15W-40 oil to fill the oil pan to the specified low level.
Remove the dipstick and scribe a mark across the dipstick at the oil level. Mark the low level with an L.
Install the dipstick and add additional oil to the specified full level.
Remove the dipstick and scribe a mark across the dipstick at the oil level. Mark the high oil level with an H.

PT (type D) Injector - Adjustment adjustment

⚠ The injector plunger is under spring tension. Do NOT allow the tool to slip.

Tools: 3822575 adjustment kit, 3822574 rocker lever actuator, ST-669 adapter

Install injector and valve adjustment kit, Part No. 3822575.
Adjust indicator tip to touch top of injector plunger.
Lower indicator 12.25 mm [0.5 inch] and lock support.
Depress rocker lever until injector bottoms two or three times.
Hold plunger bottomed and set indicator to ZERO.
Turn adjusting screw until indicator reads specified travel.
Tighten locknut; verify setting.

Valves - Adjustment adjustment

⚠ Use the correct chart for the engine being serviced or the parts will be damaged.

Tools: 3376592 Inch Pound Torque Wrench, ST-669 Torque Wrench Adapter, feeler gauge

Select a feeler gauge for the correct valve lash specification and insert the gauge between the rocker lever and the crosshead.
Torque wrench method: use Part No. 3376592 inch pound torque wrench and tighten the adjusting screw to 0.68 Nm [6 in-lb].
Feel method: use a screwdriver and turn the adjusting screw only until the lever touches the feeler gauge.
The adjusting screw must not turn when the locknut is tightened.
Tighten the locknut to the value indicated.
The feeler gauge must slide backward and forward with only a slight drag.
Attempt to insert a feeler gauge 0.03 mm [0.001 in] thicker; the lash is not correct when the thicker gauge will fit.
Repeat until clearance is correct on both intake and exhaust valves.

Valves and Injectors - General Checking and Adjustment adjustment

⚠ Use the correct chart for the engine or the parts will be damaged.

⚠ Crosshead adjustment must always be made before adjusting the valves.

Tools: 3376592 inch pound torque wrench, 3822575 injector and valve adjustment kit, 3822574 rocker lever actuator, ST-669 torque wrench adapter

Steam clean engine before removing rocker lever covers.
Remove rocker lever covers and related components.
Align valve set (VS) mark on damper or flywheel with pointer.
Determine cylinder in position; crossheads and valves ready when all valves closed.
Adjust crossheads before adjusting valves.
Adjust valves to lash specification with feeler gauge.
Adjust injectors per PT (type D) or STC/HVT method.
Tighten locknuts and reinstall rocker lever covers.

Air Cleaner Element Replacement - Single Heavy Duty Dry-Type maintenance

⚠ Holes, loose end seals, dented sealing surfaces and other damage require immediate element replacement.

⚠ Pull the cover and element straight out to avoid damage.

Wipe dirt from the cover and upper portion of the air cleaner before disassembly.
Loosen the wing bolt and band clamp securing the dust pan.
Loosen the wing nut and remove the dust shield from the dust pan. Clean the dust pan and shield.
Remove the wing nut securing the primary element and inspect the rubber sealing washer.
Remove the dirty cleaner element and install the new primary element.
Make sure the rubber sealing washer is in place under the wing nut before tightening.
Assemble the dust shield and dust pan and secure with the band clamp.

Checking Ignition Plug Gap maintenance

Tools: feeler gauge

Remove carbon
Measure clearance with feeler gauge
If clearance is out of reference value, readjust

Coolant Filter Replacement maintenance

⚠ Do NOT remove the radiator cap from a hot engine.

⚠ Do not allow oil to get in the filter; it will adversely affect the DCA.

Remove the coolant system pressure cap and close the shutoff valve(s), if equipped, before removing the coolant filter.
Push in the knob on the filter head or close the gate valve.
Lubricate the seal on the new filter with engine oil.
Install the new coolant filter. Turn the filter until the seal touches the filter head.
Turn the filter an additional 1/2 to 3/4 of a turn after contact.
Pull the knob on the filter head out or open the gate valve.

Cooling System - Cleaning System and Changing Antifreeze maintenance

⚠ Do not use caustic cleaners; aluminum components will be damaged.

⚠ Wait until temperature is below 50 C [120 F] before removing the pressure cap.

Drain the cooling system; do not allow it to dry out.
Add Fleetguard RESTORE or RESTORE PLUS (1 U.S. gallon per 38-57 liters capacity).
Fill system with plain water.
Operate engine at normal temperature (at least 85 C [185 F]) for 1 to 1.5 hours.
Shut off and drain the system.
Fill with clean water and operate at high idle 5 minutes above 85 C.
Shut off and drain; repeat flush if water is still dirty.
Refill with new heavy duty coolant and SCA.

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

Which generators use the GN1850-DG-A3 engine?

The GN1850-DG-A3 powers 2 generator set(s), including Cummins/Onan K1800, Cummins/Onan K2100.

What is a common problem with the GN1850-DG-A3 engine?

A commonly reported issue on generators using the GN1850-DG-A3 is: Only slight output voltage is delivered (3 ~ 6V). Cause: Worn brush or faulty contact surface of slip ring. Fix: Clean brush contact and slip ring, or replace brush.