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Kubota D905BG-2 Engine

The Kubota D905BG-2 is a 0.9 L 3-cylinder four-cycle engine rated at 1800 rpm, producing up to 5.1 kW. It powers generator sets from FG Wilson and Kohler, including the D905-BG2, DCP-10, KUBOTA and 7CCFO. It holds 5.1 L (1.3 gal) of oil and 2.3 L (0.6 gal) of coolant.

Also known as: Kubota D905BG-2

0.898 L

Displacement

Cylinders

1800 rpm

Rated speed

5 kW

Gross power

On this pageService parts Specs Generator sets Maintenance Filter cross-reference FAQ Service intervals Torque & specs Fluids Procedures Wiring

Service parts for the D905BG-2

The cheapest captured merchant offer per filter — see the full cross-reference below for every OEM/aftermarket option.

Air intake

1 required

K318182240Air filterfind

Fuel system

1 required

1258143013Fuel filter$6.98PartsGeek

Oil system

1 required

229678Oil filter$7.98PartsGeek

Prices captured from merchant listings; some links are affiliate links. Verify against your serial number before ordering.

Engine specifications

Oil capacity	5.1 L
Coolant capacity	2.3 L
Displacement	0.898 L
Cylinders	3
Aspiration	four-cycle
Rated speed	1800 rpm
Gross power	5 kW

Generator sets powered by this engine

Shared across brands: FG Wilson, Kohler

FG Wilson D905-BG2FG Wilson DCP-10 FG Wilson KUBOTAKohler 7CCFOKohler 7CCO

How to read your Kubota engine serial & model number →

Common problems

Will not start (cranks okay)
Fix: Replenish, Check continuity, Replace fuel feed pump, Clean or replace element, Troubleshoot engine, Bleed air, Drain, flush fuel system, Check injectors, Check compression, Use proper type of fuel; consult fuel supplier, Use proper lube oil, Check valve clearance, Replace filter, Check continuity, Check relay coil continuity, Service/Engine Service Manual
Will not carry load pump
Cause: Defective injection pump or runs rough
Fix: Check injection pump, engine speed using frequency meter or tachometer. NOTE: Hz x 120/No. of rotor poles = rpm (Example: 60 x 120/4 = 1800)
Unit is noisy
Cause: Excessive vibration—engine/generator, Exhaust system leak, Broken or damaged vibro mounts, Loose or vibrating sheet metal/housing, Inadequate compartment clearances, Exhaust piping or air inlets/outlets not securely installed, No compartment sound insulation
Fix: Check and replace as necessary, Check and replace as necessary, Retighten screws, Check clearances, Inspect for loose parts, Install fireproof insulation, Check rotor, crankshaft, bearing, etc. (Disassembly of engine and/or generator may be required)
Starter does not work properly
Cause: Loose or corroded wiring, Low battery output, Defective starter relay, Defective start/stop switch, Defective wiring, Battery cables undersize
Fix: Clean and tighten loose connections, Check electrolyte level and specific gravity (batteries with filler caps only), Check starter relay, Replace starter relay, as necessary, Replace switch, Check wiring, Replace starter, Select proper size cable
Starter cranks slowly
Cause: Low battery output, Too heavy viscosity lube oil, Loose or corroded wiring, High starter current draw, Battery cable undersize
Fix: Check electrolyte level and specific gravity (batteries with filler caps only), Use proper viscosity oil, Clean and tighten loose connections, Repair/Replace starter, Select proper size cable
Overheats
Cause: Improper cooling, Air cleaner clogged
Fix: Check cooling system (Check hoses for blockage and components for function.), Clean or replace element
Operates erratically
Cause: Air cleaner clogged
Fix: Clean or replace element
Open wiring (P1 or P2 connector)
Fix: Check continuity
No/low oil pressure (time delay of 5-10 seconds on E-239563 circuit board)
Fix: Correct fault condition; Section 9. Wiring Diagrams
No generator output voltage
Cause: Optional AC output circuit breaker open or defective, Optional AC circuit breaker tripping due to overload on unit, Transfer switch in OFF or other power source position, No battery voltage to terminal (+) and (-) of voltage regulator during cranking, Fuse blown in voltage regulator circuit (lead 55), Short circuit in coach wiring causing circuit breaker to trip, Open wiring, terminals or pin in aux. winding circuit (field flashing), Defective rotor (open, grounded, or shorted windings), Defective stator (open, grounded, or shorted windings), Open D5 or D8 diode
Fix: Check position of circuit breaker, Check AC voltage on generator side of circuit breakers, Reduce load, Reset and attempt startup, Turn handle to proper position, Check for 12 VDC at voltage regulator (+
Low oil pressure (LOP) or high water temperature (HWT) fault
Fix: Correct fault condition
Lacks power
Cause: Governor not properly adjusted or defective, Air cleaner clogged, Carbon build-up, Improper cooling, Engine overloaded, Stale or bad fuel, Fuel line restriction, Dirty fuel filter
Fix: Check engine speed using frequency meter or tachometer. NOTE: Hz x 120/No. of rotor poles = rpm (Example: 60 x 120/4 = 1800), Clean or replace element, Clean carbon from cylinder heads, Inspect cooling system, Reduce electrical load, Replace fuel filter
K1 relay coil defective.
Fix: Check continuity
K1 relay coil defective
Fix: Check continuity
If LED1 is not lit, K1 relay is not receiving power from stator B1/B2 winding
Fix: Check oil pressure, oil pump, and low oil pressure shutdown switch

Compiled from service & troubleshooting documentation across every generator set that uses the Kubota D905BG-2.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Clean or replace element		—	500 hr
Fuel filter	Clean or replace element		1258143013	1000 hr	Amazon eBay $17.87 PartsGeek $6.98 KuduParts $10.00
Oil filter	Clean or replace element		229678	500 hr	Amazon eBay $24.45 PartsGeek $7.98 NAPA $9.09
Battery	Check the electrolyte level in the battery		—	500 hr
Belt	Check and replace as necessary, Check clearances, Inspect for loose parts, Install fireproof insulation		—	1000 hr
Coolant filter	Check and replace as necessary, Check clearances, Inspect for loose parts, Install fireproof insulation		—	1000 hr
Oil	Check the oil level in crankcase	5.1	—	50 hr
Spark plug	Check and replace as necessary, Check clearances, Inspect for loose parts, Install fireproof insulation		—	1000 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
Battery electrolyte level	Check	50 hr	1 mo
Electrical connections	Check	50 hr	1 mo
Fuel pipes and clamps	Check	50 hr	1 mo
Battery charging alternator V-belt	Adjust	100 hr	3 mo
Battery specific gravity	Test	100 hr	3 mo
Lube oil filter element	Replace	100 hr	3 mo	First service — First replacement at 50 hours or 1 month
Oil in crankcase	Change	100 hr	3 mo	First service — New engine: change after first 50 hours
Water pipes and clamps	Check	100 hr	3 mo
Water pump V-belt tension	Adjust	100 hr	3 mo
Air cleaner element	Replace	400 hr	6 mo	Service more often in dusty conditions
Fuel filter element	Replace	400 hr	6 mo	First replacement at 50 hours or 1 month
Breather pipe	Clean	500 hr	12 mo
Coolant	Change	500 hr	12 mo	Antifreeze also changed every two years
Cylinder head bolts	Adjust	500 hr	12 mo	Retighten; authorized dealer
Fuel tank sediment	Drain	500 hr	12 mo	Remove sediment
Gauges (if equipped)	Test	500 hr	12 mo	Verify proper operation
Governor operation	Adjust	500 hr	12 mo	Check and adjust as necessary; authorized dealer
Leakage of water and oil	Check	500 hr	12 mo
Major nuts and bolts	Adjust	500 hr	12 mo	Retighten
Mounting bolts and vibro mounts	Check	500 hr	12 mo	Check for tightness
Radiator fins and hoses	Clean	500 hr	12 mo	Inspect hoses
Intake/exhaust valve clearance	Adjust	800 hr	6 mo	Authorized dealer
Nozzle injection pressure	Test	1000 hr		Authorized Kohler Service Dealer

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	Slip ring maximum size after turning	2.391	inches
Clearance	Slip ring minimum size after turning	2.360	inches
Gap	Belt tension (deflection)	0.28 to 0.35	in (7 to 9 mm) at 22 lbs (10 kg)
Other	Angular operation (max.)	20 continuous / 30 for 10 minutes or less	degrees	in all directions
Other	Frequency regulation	+5	%
Other	Fuel solenoid hold current	0.8	amps
Other	Fuel solenoid pull current	31	amps	momentary
Other	Maximum fuel/water separator centerbolt torque	65	inch pounds
Other	Slip ring surface finish	64	micro-inch
Pressure	Coolant fill pressure cap	13	psi (89 kPa)
Pressure	Engine oil pressure (normal operating range)	36-50	psi (248-345 kPa)
Pressure	Fuel injection pressure	1991-2133	psi (140-150 kgf/cm2)
Pressure	Low oil pressure (LOP) shutdown switch	7	psi (48.3 kPa)	contacts close at approx.
Pressure	Radiator pressure cap	20-24	psi (138-165 kPa)
Resistance	Fuel solenoid plunger hold resistance	14.94	ohms	solenoid disconnected from harness
Resistance	Fuel solenoid plunger pull resistance	0.387	ohms	solenoid disconnected from harness
Resistance	Glow plug relay (C1)	approx. 16-20	ohms	at 80F (27C)
Resistance	K1 relay coil	approx. 160	ohms	controller circuit board E-239563
Resistance	K2 relay coil	approx. 160	ohms	controller circuit board E-239563
Resistance	K20 relay coil	85	ohms
Resistance	K25 relay coil	85	ohms
Resistance	K3 relay coil	approx. 400	ohms	controller circuit board E-239563
Resistance	K4 relay coil	approx. 125	ohms	controller circuit board E-239563
Resistance	K5 relay coil	approx. 510	ohms	controller circuit board E-239563
Resistance	Oil pressure sender (VDO 2/4-meter panel)	227-257 / 138-162 / 92-114 / 50-80 / 21-50	ohms at 0/25/50/75/100 PSI
Resistance	Rotor resistance (cold)	3.9	ohms	room temperature approx. 70F (21C)
Resistance	Rotor resistance (cold)	4.3	ohms	room temperature approx. 70F (21C)
Resistance	Starter relay (S relay)	approx. 0.20-0.35	ohms	at 80F (27C)
Resistance	Stator 1-2, 3-4, 33-44 (cold)	0.12	ohms	room temperature
Resistance	Stator 1-2, 3-4, 33-44 (cold)	0.13	ohms	room temperature
Resistance	Stator 33-55 (cold)	1.5	ohms	room temperature
Resistance	Stator 33-55 (cold)	1.6	ohms	room temperature
Resistance	Stator B1-B2 (cold)	0.07	ohms	room temperature
Resistance	Stator B1-B2 (cold)	0.08	ohms	room temperature
Resistance	Water temperature sender (VDO 2/4-meter panel)	450 / 130 / 47	ohms at 100F/160F/220F (38/71/104C)	+/-10%
Speed	50 Hz operation - full load	1500	rpm	50-52.5 Hz, full load
Speed	50 Hz operation - no load	1575	rpm	50-52.5 Hz, no load
Speed	60 Hz operation - full load	1800	rpm	60-63 Hz, full load
Speed	60 Hz operation - no load	1890	rpm	60-63 Hz, no load
Temperature	Engine coolant temperature (normal operating range)	180-205	F (82-96 C)
Temperature	High water temperature (HWT) shutdown switch	230	F (110 C)	contacts close at approx.
Torque	Alternator overbolt	300	in lbs (25 ft lbs)
Torque	Cylinder head bolts	47.0-50.6	ft lbs (63.7-68.6 Nm)	apply engine oil; tighten in sequence
Torque	Drive disk to flywheel bolts	14	ft lbs (168 in lbs)	follow tightening sequence
Torque	Drive disk to rotor bolts	28	ft lbs (338 in lbs)	follow tightening sequence
Torque	End bracket/stator overbolts	25	ft lbs (300 in lbs)
Torque	Fuel/water separator centerbolt	65	inch pounds
Valve clearance	Intake/exhaust valve clearance	0.006-0.007	in. (0.145-0.185 mm)	engine cold
Voltage	Battery charging alternator output	20	Amps @ 12 Volts
Voltage	Rotor field voltage/current - full load (60 Hz)	38 V / 6.7 amps	V / amps	hot
Voltage	Rotor field voltage/current - full load (60 Hz)	41 V / 5.5 amps	V / amps	hot, rated output voltage
Voltage	Rotor field voltage/current - no load (63 Hz)	16 V / 2.5 amps	V / amps	hot, rated output voltage
Voltage	Rotor field voltage/current - no load (63 Hz)	18 V / 3.2 amps	V / amps	hot
Voltage	Stator output voltage with separately excited rotor (1-2, 3-4, 33-44)	105	volts	using 12-volt battery
Voltage	Stator output voltage with separately excited rotor (1-2, 3-4, 33-44)	107	volts	using 12-volt battery
Voltage	Stator output voltage with separately excited rotor (33-55)	125	volts	using 12-volt battery
Voltage	Stator output voltage with separately excited rotor (B1-B2)	12	volts	using 12-volt battery
Voltage	Voltage regulation	+2	%

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 / 50% clean softened water	must contain rust inhibitor	above -37°C	2.3 L	Protects to -34F (-37C); do not use alcohol or methanol antifreeze; 10CCO capacity 5.4 L
Engine oil	SAE 10W or 10W-30	API CC, CD or CE	below 0°C	5.4 U.S. qts	Below 32F (0C)
Engine oil	SAE 20 or 10W-30	API CC, CD or CE	0°C to 25°C	6.3 U.S. qts	32-77F (0-25C); 6.3 qts is 10CCO capacity
Engine oil	SAE 30 or 10W-30	API CC, CD or CE	above 25°C		Above 77F (25C)
Fuel	No. 2-D diesel (DIN 51 601)	ASTM D975 (Federal Specification W-F-800a), BS2869 Class A1			Sulfur <0.5%; sediment/water max 0.05%; cetane min 45; flash point at least 125F (52C)

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

Procedures

Belt Tension Adjustment adjustment

⚠ Exposed moving parts. Keep hands away from belts and pulleys; replace guards.

Loosen pivot and adjusting screws.
Pry battery charging alternator outward; tighten adjusting screw.
Tighten pivot screw.
Recheck and adjust as necessary.

Governor Speed Adjustment adjustment

Tools: tachometer, frequency meter

Check speed using handheld tachometer or frequency meter.
Loosen locking nut on speed-adjusting screw.
Turn screw clockwise to increase speed, counterclockwise to decrease.
Tighten locknut to secure screw at new setting.

Valve Clearance Adjustment adjustment

⚠ Flying projectiles. Rotate crankshaft clockwise only; do not loosen rotor thru-bolt.

Tools: feeler gauge

Remove rocker arm cover screws and breather hose.
Remove rocker arm cover; wipe excess oil from components.
Rotate engine until No. 1 piston is at Top Dead Center.
Insert feeler gauge between rocker arm and exhaust valve.
Loosen locknut; move adjusting screw so slight drag is felt.
Tighten locknut; recheck clearance.
Repeat for each additional cylinder.
Install rocker arm cover with gasket properly seated.

Separate Excitation Test diagnostic

⚠ Hazardous voltage. Perform electrical service only as prescribed.

Tools: ammeter, 12-volt automotive battery, 10-amp fuse

Disconnect all leads from voltage regulator.
Connect ammeter and 12-volt battery to brush leads; include 10-amp fuse.
Ammeter reading equals battery voltage divided by rotor resistance.
Start engine; check that ammeter remains stable.
Check AC output across stator leads; compare to Section 10 specifications.
If rotor and stator test good, replace voltage regulator.

Air Cleaner Element Replacement maintenance

⚠ Do not clean dry-type element in liquid or with compressed air.

Loosen eye bolt and clamp; remove air cleaner cover.
Remove wing nut; slide element off threaded rod.
Clean dry element by tapping edges; replace if damaged or very dirty.
Wipe dirt from cover and base; check clamps are tight.
Install element on threaded rod; tighten wing nut.
Position cover with arrow up; tighten eye.

Bleeding the Fuel System maintenance

⚠ Explosive fuel vapors. Use a container to catch fuel; wipe up all spilled fuel.

Fill the fuel tank to the fullest extent.
Loosen the small vent screw a few turns on the fuel filter.
Operate the fuel pump until bubble-free fuel flows; tighten vent screw.
Loosen line connection (bleed point) at injection pump inlet.
Operate fuel pump until bubble-free fuel flows; tighten connection.

Fuel Filter Replacement maintenance

Loosen fuel filter counterclockwise; remove and discard.
Clean contact surface on fuel filter adapter.
Lubricate new gasket with fresh fuel oil.
Thread filter until gasket contacts; hand-tighten one-half turn.
Bleed the fuel system.

Fuel/Water Separator Element Replacement maintenance

Close fuel valve at tank or separator inlet.
Remove water drain plug; drain water and fuel.
Remove element with bowl from mounting head.
Remove bowl; inspect O-ring and components for wear.
Lubricate O-ring with clean diesel or motor oil; replace in bowl.
Replace bowl onto new element; fill with clean fuel.
Tighten centerbolt to 65 inch pounds.
Replace drain plug; open fuel valve; bleed system.

Oil Change maintenance

⚠ Too high an oil level causes high oil consumption and carbonizing.

Place container below oil drain; remove drain plug.
Drain oil completely; replace drain plug.
Remove either oil fill cap.
Fill crankcase with proper amount and type of oil.
Start generator set; check for oil leaks.
Stop set; check level at dipstick MAX mark.

Oil Filter Replacement maintenance

Tools: filter wrench

Loosen oil filter counterclockwise with filter wrench; remove and discard.
Clean contact surface on oil filter adapter.
Lubricate new filter gasket with fresh engine oil.
Thread filter to adapter until gasket contacts; hand-tighten one-half turn.
Replace engine oil.
Start set; check for oil leaks.
Stop set; check oil level at dipstick.

Storage Procedure maintenance

Drain oil while hot; refill with regular grade oil.
Drain fuel from the fuel tank.
Check engine coolant protection.
Disconnect battery (negative lead first); place in storage.
Seal all engine openings with non-absorbent adhesive tape.
Clean exterior; spread light film of oil on unpainted metal.

Cylinder Head Retightening repair

⚠ Always use new cylinder head gaskets.

Tools: torque wrench

Remove cylinder head screws in order (14 or 18) to (1).
Remove cylinder head gasket and O-ring; replace gasket.
Install cylinder head, making sure not to damage O-ring.
Tighten screws gradually in order (1) to (14 or 18) after applying engine oil.
Retighten cylinder head screws after running engine 30 minutes.

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
120	1	120 volt, 2 wire (non-CSA)	Jumper lead on line side of circuit breaker	Single-pole circuit breaker required; use jumper lead for load balancing.
120	1	120 volt, 3 wire (non-CSA)	LO-L1 = 120 volt; LO-L2 = 120 volt	Stator leads 4-3-2-1; 50 Hz: LO-L1/L0-L2 = 110 volt. Factory two-pole circuit breaker; load-side terminals not connected together. Decal part no. 246242 for voltage change notice.
120/240	1	120/240 volt, 3 wire	LO-L1 = 120 volt; LO-L2 = 120 volt; L1-L2 = 240 volt	Jumper lead not used. 50 Hz: 110/110/220 volt. Circuit breaker MUST be a manufacturer two-pole breaker. L1 and L2 must never be connected together.

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

Filters for this engine

Air filter: Kubota K318182240 Kubota K318182250 Kubota TD27093230 Kubota TD27093220 Donaldson P778979 Donaldson P780018 Donaldson P526873 Donaldson P778984
Fuel filter: Kubota 1258143013 Donaldson P550012 Donaldson P550248 Donaldson P550588 Wix 33032 Ac Delco GF142 Baldwin BF840-K1 Wix 33472
Oil filter: Kohler 229678 Kubota 7665025430 Donaldson P550162 Wix 51334 Ac Delco X45 Baldwin B179

Cross-referenced via Donaldson + OEM/engine-maker interchange — options to verify against your serial number, not confirmed for every exact variant.

Also used in

Atlas Copco XAS37 — Compressor
Kaeser MOBILAIR M22 — Compressor

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.

Common questions

What is the oil capacity of the Kubota D905BG-2?

The Kubota D905BG-2 engine has an oil capacity of 5.1 liters.

What is the displacement of the Kubota D905BG-2?

The Kubota D905BG-2 has a displacement of 0.898 liters with 3 cylinders.

Which generators use the Kubota D905BG-2 engine?

The Kubota D905BG-2 powers 5 generator set(s), including FG Wilson D905-BG2, FG Wilson DCP-10, FG Wilson KUBOTA, Kohler 7CCFO, Kohler 7CCO.

What oil filter does the Kubota D905BG-2 use?

The Kubota D905BG-2 uses oil filter part numbers Kohler 229678, Kubota 7665025430, Donaldson P550162.

What fuel filter does the Kubota D905BG-2 use?

The Kubota D905BG-2 uses fuel filter part numbers Kubota 1258143013, Donaldson P550012, Donaldson P550248.

What air filter does the Kubota D905BG-2 use?

The Kubota D905BG-2 uses air filter part numbers Kubota K318182240, Kubota K318182250, Kubota TD27093230.

How often should you change the oil in the Kubota D905BG-2?

The Kubota D905BG-2 oil change interval is every 50 hours.

What is a common problem with the Kubota D905BG-2 engine?

A commonly reported issue on generators using the Kubota D905BG-2 is: Will not start (cranks okay). Fix: Replenish, Check continuity, Replace fuel feed pump, Clean or replace element, Troubleshoot engine, Bleed air, Drain, flush fuel system, Check injectors, Check compression, Use proper type of fuel; consult fuel supplier, Use proper lube oil, Check valve clearance, Replace filter, Check continuity, Check relay coil continuity, Service/Engine Service Manual.