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Subaru EX21 Engine

The Subaru EX21 is a 0.21 L air-cooled 4-stroke ohc gasoline engine. It powers generator sets from Cummins/Onan, including the P3200i. It holds 0.63 L (0.2 gal) of oil and 25.3 L (6.7 gal) of coolant.

Also known as: EX21, Subaru EX21

0.211 L

Displacement

0.63 L

Oil capacity

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

Engine specifications

Oil capacity	0.63 L
Coolant capacity	25.3 L
Displacement	0.211 L
Aspiration	Air-Cooled 4-stroke OHC Gasoline

Generator sets powered by this engine

Cummins/Onan P3200i

This engine also powers 23 machine(s) on Power Equipment Info.

Common problems

When No Electricity Is Generated at Receptacle
Fix: Check fuel level. Check to make sure generator is not connected to an appliance. Check spark plug for loose spark plug cap. Check spark plug for contamination. Check engine oil level. Check if the recommended spark plug would be adopted. If empty, refill fuel tank making sure not to overfill. If connected, turn off the power switch on the connected appliance and unplug. If loose, push spark plug cap back into place. Remove spark plug and clean electrode. If the engine oil level is low, add the oil to the upper level line on the oil gauge. If not, replace with the recommended spark plug. If the recommended spark plug is not available by all means, make sure to replace with equivalent one of resistance type.
When Engine Fails to Start
Fix: Check if the DC circuit breaker is turned OFF. Check if the 'O_Lod' (overload) is indicated in the Multi Monitor. Check AC receptacle and DC terminals for loose connection. Check to see if engine starting was attempted with appliances already connected to generator. Depress the circuit breaker into ON position, after making sure the charging current level is proper and the battery is in the normal condition. Stop the engine and check the appliance and/or generator for overloading. Secure connection if necessary.
Unit Starts And Runs, Then Stops When The Start Switch Is Released
Cause: Low fluid levels, Possible overheating, Other functional problem
Fix: Check & bring all fluids up to the appropriate levels, Check for blocked air flow or other possible causes of overheating, Contact an Cummins Onan Authorized RV Service & Parts Dealer
Unit Runs Then Surges
Cause: Loose or worn spark plug leads, Defective ignition coil, wiring, or control components, Faulty spark plug, Governor out of adjustment, Combustion air pre-heat malfunction, Carburetor icing, Carburetor varnishing
Fix: Check spark plug leads at spark plug & ignition coil, Contact an Cummins Onan Authorized RV Service & Parts Dealer, Remove spark plug & clean or replace, Contact an Cummins Onan Authorized RV Service & Parts Dealer, Contact an Cummins Onan Authorized RV Service & Parts Dealer, Contact an Cummins Onan Authorized RV Service & Parts Dealer
Unit Runs Then Stops, Or Stops When Driving Around A Corner
Cause: Low fuel level, Low oil level, Excess oil
Fix: Add fuel, Add oil, Reduce engine oil level
Fails To Crank
Cause: Low battery, Bad battery connection, Blown fuse
Fix: Check battery fluid level, Clean & tighten all battery & cable connections, Replace fuse on control panel
Exhausting Black Smoke
Cause: Dirty air filter
Fix: Replace air filter
Cranks But Won’t Start
Cause: Fuel below generator pickup level in tank, Fuel supply shutoff valve closed, Carbon deposits on spark plug(s), Low oil level
Fix: Add fuel, Fully open fuel supply valve, Remove spark plug(s) and replace, Add oil
Circuit Breaker Trips
Cause: Overloaded circuit
Fix: Turn-off some of the electrical load, and reset the circuit breaker

Compiled from service & troubleshooting documentation across every generator set that uses the Subaru EX21.

Service intervals

Item	Action	Hours	Months	Notes
Oil level	Check	8 hr		Check oil daily or every 8 hours of operating time; perform a general inspection daily per Operator's Manual
Engine oil	Change	50 hr		First service — Break-in: change engine oil after the first 20-50 hours of operation (RV QG/RV QG RM); perform at least once a year
Battery & connections	Clean		1 mo	Clean & check battery & connections; perform more often in hot weather
Oil/oil filter - Quiet Diesel 10000/12500	Change			First service — Break-in then repeat (footnotes 1-4, 2-4)
Oil/oil filter - Quiet Diesel 5500	Change			First service — Break-in then repeat (footnotes 1-4, 2-4)
Oil/oil filter - Quiet Diesel 7500/8000	Change			First service — Break-in then repeat (footnotes 1-4, 2-4)
Spark arrester	Clean		1 mo	Clean arrester; perform sooner if engine performance deteriorates

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
Other	Cummins Onan Generator Tester part number	388-47565-08		measuring range 0-500 V AC, 25-70 Hz, 0.1-1,999 Ω, 10-100 µF, 3 MΩ
Other	Power output change with altitude	3.5	% decrease per 1000 ft increase	typical power output change based on ambient conditions
Other	Power output change with temperature	1	% decrease per 10 degF increase	typical power output change based on ambient conditions
Resistance	Insulation resistance (generator)	1	MΩ	minimum normal value
Resistance	Insulation resistance at shipment from factory	10	MΩ	original value
Resistance	Inverter unit insulation (4P connector)	5	MΩ
Resistance	Inverter unit output wires to 4P connector (110V/120V spec)	0.6	kΩ
Resistance	Inverter unit output wires to 4P connector (220V/230V/240V spec)	2.7	kΩ
Resistance	Stator 4P connector Blue – Red	0.8	Ω	at 20°C (values listed as 0.8 / 1.1)
Resistance	Stator 4P connector Blue – Red	1.1	Ω	at 20°C (values listed as 0.8 / 1.1)
Resistance	Stator 4P connector Red – White	2.1	Ω	at 20°C; 220/230/240V spec
Resistance	Stator 4P connector Red – White	2.8	Ω	at 20°C; 220/230/240V spec (values listed as 2.8 / 4.0)
Resistance	Stator 4P connector Red – White	4.0	Ω	at 20°C; 110/120V spec (values listed as 2.8 / 4.0)
Resistance	Stator 4P connector White – Blue	0.8	Ω	at 20°C (values listed as 0.8 / 1.1)
Resistance	Stator 4P connector White – Blue	1.1	Ω	at 20°C (values listed as 0.8 / 1.1)
Resistance	Stator 8P connector Brown – Brown	0.1	Ω	at 20°C
Resistance	Stator 8P connector White – White	0.2	Ω	at 20°C
Resistance	Stator 8P connector Yellow – Yellow	0.1	Ω	at 20°C
Speed	Correct engine revolution (no output / low output troubleshooting)	3550-3650	rpm	turn of the APS switch
Temperature	Ambient conditions for rated power output	77	degF	with muffler and RV enclosure, per ISO 8528-1; altitude 500 ft (152.4 m), 99 kPa dry
Torque	Alternator components	6.5 - 8.5	N·m	(60 - 85 kgf·cm / 4.8 - 6.3 ft·lbs)
Torque	Alternator components	7.5 - 9.5	N·m	(75 - 95 kgf·cm / 5.5 - 7.0 ft·lbs)
Torque	Alternator through bolt	19.0 - 21.0	N·m	(190 - 210 kgf·cm / 14.0 - 15.5 ft·lbs)
Torque	Blower housing	18.0 - 22.0	N·m	(180 - 220 kgf·cm / 13.3 - 16.2 ft·lbs)
Torque	Blower housing (M6 x 35 / M6 x 45)	8.0 - 10.0	N·m	(80 - 100 kgf·cm / 5.9 - 7.4 ft·lbs)
Torque	Bottom extension plate / separators	4.0 - 6.0	N·m	(40 - 60 kgf·cm / 3.0 - 4.4 ft·lbs)
Torque	Carburetor / air cleaner base	6.0 - 8.0	N·m	(60 - 80 kgf·cm / 4.4 - 5.9 ft·lbs)
Torque	Control box / inverter unit	4.0 - 6.0	N·m	(40 - 60 kgf·cm / 3.0 - 4.4 ft·lbs)
Torque	Cover (crankshaft) / Fan (silent)	18.0 - 22.0	N·m	(180 - 220 kgf·cm / 13.3 - 16.2 ft·lbs)
Torque	Flywheel fan and drive shaft (M8 x 27mm flange bolt)	25.0 - 27.0	N·m	(250 - 270 kgf·cm / 18.4 - 19.9 ft·lbs)
Torque	Flywheel nut (M19)	10.0 - 12.0	N·m	(100 - 120 kgf·cm / 7.4 - 8.7 ft·lbs)
Torque	Flywheel nut (M19)	59.0 - 64.0	N·m	(590 - 640 kgf·cm / 43.5 - 47.2 ft·lbs)
Torque	Fuel tank / fuel system flange bolt (M6)	4.0 - 6.0	N·m	(40 - 60 kgf·cm / 3.0 - 4.4 ft·lbs)
Torque	Muffler	17.0 - 19.0	N·m	(170 - 190 kgf·cm / 12.5 - 14.0 ft·lbs)
Torque	Muffler (M8 flange nut / M6 x 23mm flange bolt)	4.0 - 6.0	N·m	(40 - 60 kgf·cm / 3.0 - 4.4 ft·lbs)
Torque	Rear cover	6.5 - 8.5	N·m	(65 - 85 kgf·cm / 4.8 - 6.3 ft·lbs)
Torque	Recoil starter	6.5 - 8.5	N·m	(65 - 85 kgf·cm / 4.8 - 6.3 ft·lbs)
Voltage	AC output voltage range 120V / 60Hz	117-130	V	at rated amperage and rated rpm
Voltage	AC output voltage range 220V / 50Hz	215-238	V	at rated amperage and rated rpm
Voltage	AC output voltage range 230V / 50Hz	225-248	V	at rated amperage and rated rpm
Voltage	AC output voltage range 240V / 60Hz	235-259	V	at rated amperage and rated rpm
Voltage	DC output voltage range (at 8.3A)	6 to 14	V	current regulated at 8.3A; increases approx. 1 to 2 V with battery load

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	Capacity	Notes
Coolant	50/50 ethylene glycol based antifreeze and water			Mix thoroughly before adding; use clean soft tap water, distilled water or pure rain; select high quality antifreeze with corrosion inhibitors
Engine oil	SAE 10W-30 / 10W-40 / 0W-30 / 5W-30			Use viscosity chart to select grade for expected ambient temperature range; avoid mixing grades or brands
Engine oil	SAE 15W-40	API CF, CF-4, CG-4, CH-4, CI-4 or CJ-4 (diesel)		OnaMax 15W-40 #326-5336; multi-grade recommended year-round in liquid-cooled engines; synthetic oil not recommended
Engine oil	SAE-30	API SJ, SL or SM (gasoline)		OnaMax SAE-30 #326-5339; preferred summer grade for optimum oil consumption control in air-cooled engines
Fuel	ASTM No.2-D / No.1-D / No.2-DLS / No.1-DLS / B5 Biodiesel	minimum Cetane number 45		No.2-D or No.2-DLS above 23 degF; No.1-D or No.1-DLS below 23 degF; B5 Biodiesel above 50 degF; use No.1 diesel below 32 degF and during long light-load periods; cloud point at least 10 degF below lowest expected fuel temperature
Fuel	HD-5 grade liquid propane	at least 90% propane		Fuels other than HD-5 can contain more than 2.5% butane causing poor vaporization/starting below 32 degF
Fuel	Regular unleaded gasoline	Ethanol blend not more than 10% ethanol; methanol blend not more than 5% methanol		Use fresh gas, not more than 30 days old; fuel stabilizer extends fuel life
Fuel	Unleaded Automobile Gasoline			Spec table prints 'Fuel / Unleaded Automobile Gasoline / 100'.
Other	Cummins Onan Premium Fuel System Cleaner		12.0 oz	Treats up to 24 gallons of gasoline; #326-5342
Other	OnaFresh GXLP fuel stabilizer		16.0 oz	Treats 40 gallons of gasoline; #326-5365

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
O_Load	Overload warning	Overload warning displayed on the multi monitor.	Warning	Stop the engine, reset the overload warning and remove the electric equipment that is connected.
O_Lod	Overload	Indicated on the multi monitor LED display when the generator is in overload condition or appliance(s) is out of order.	Warning	Stop the engine immediately and check the appliance and/or generator for overloading. After the check and remedy, restart the engine.

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

Procedures

Measuring Insulation Resistance diagnostic

⚠ Any part with insulation resistance less than 1 MΩ has faulty insulation and may cause electric leakage and electric shock; replace the faulty part.

Tools: Megger tester, Cummins Onan generator tester

Use a Cummins Onan generator tester in megger mode or a megger tester (500V range).
Connect the tester to one receptacle output terminal and the ground terminal.
Measure the insulation resistance.
If below normal, disassemble and measure stator, rotor and control panel individually.
For stator, check resistance between red lead and core, blue lead and core, and white lead and core.
For control panel, measure resistances between live parts and grounded parts.

Stator and Inverter Unit Checking diagnostic

⚠ An inaccurate circuit tester may give erroneous readings.

Tools: Circuit tester

Disengage connectors on the wires from the stator.
Check the resistance between the wires using a circuit tester.
For inverter unit, check for color change or blister in the filling resin.
Check conductivity between the output wires and the 4P connector.

Disassembly and Assembly Preparation and Precautions maintenance

⚠ Failure to reattach foam rubber linings will result in poor performance and durability.

Memorize and tag the location of individual parts before disassembling.
Divide parts into groups and store them in boxes.
Replace bolts and nuts temporarily in their original positions.
Clean disassembled parts with neutral cleaning fluid before reassembly.
Remove the battery before disassembling the generator (electric start models).
Use the proper tool for each specific job.
Attach foam rubber linings inside covers on their original position; replace if deformed or damaged.
Bind wires and fuel pipes using wire bands as in original configuration.

Air Cleaner and Carburetor Removal repair

⚠ Use caution not to break the gasket.

Tools: 10mm Box wrench

Remove the air cleaner cover and element from the air cleaner.
Loosen the two M6 nuts and one M6 bolt, and remove the air cleaner body.
Carefully remove the carburetor from the insulator without breaking the gasket.
Remove the sponge insulator.

Control Panel and Inverter Unit Removal repair

⚠ Electric wires are still connected to the control panel; do not separate the control panel forcibly.

Tools: Screw driver, Nipper

Loosen the four screws and remove the upper front cover.
Loosen the two bolts and remove the lower front cover.
Loosen the five bolts and remove the cover bracket from the inverter unit.
Remove the fuel tank before separating the control panel.
Cut the wire bands binding wires behind the control panel.

Engine Block Removal repair

Tools: 12mm Box wrench

Loosen the four M8 nuts that fasten the engine to the mount rubbers, and remove the engine.
Remove the mount rubbers from the frame as necessary.

Flywheel Installation repair

Tools: Flywheel holder (33B9990101)

Wipe off oil from the tapered portion of the crankshaft and the hole of flywheel before assembly.
Install the flywheel onto the crankshaft and tighten the flywheel nut using the Flywheel Holder.

Flywheel Removal repair

Tools: Flywheel holder (33B9990101), Socket wrench, Flywheel puller (available on market)

Using special tool Flywheel Holder to hold the flywheel, loosen the flywheel nut.
Remove the flywheel using an ordinary flywheel puller.

Fuel Pipes, Fuel Strainer and Battery Cables Removal repair

Turn the engine switch to STOP position to close the fuel cock.
Disconnect the two fuel pipes from the fuel strainer.
Remove the fuel strainer.
For electric start models: remove the battery cover and disconnect battery cables.
Remove the battery from frame.

Fuel Tank Removal repair

Tools: 10mm Box wrench

Drain fuel from the tank before removing the tank.
Loosen the four bolts and remove the fuel tank from frame.
Take care not to misplace the four mounting rubbers for the tank.

Recoil Starter Assembly repair

⚠ Do not release pressure on the reel while winding the spiral spring; sudden rewinding may occur.

⚠ Wear protective goggles before assembly.

Tools: Protective goggles

Apply grease to the case; orient the inner end of the spring in the reel.
Hold the reel so the shaft and hook catch on the inner end of the spring, softly drop into the case from the top.
Move the reel gently counter-clockwise so the spring catches.
Install the ratchet and friction spring into the reel.
Install the friction plate tab into the hole of the ratchet and fasten with retaining ring C.
Hold the case and turn the reel five turns counter-clockwise.
Thread the rope end through the rope guide and reel hole, pull 20cm out and fix the rope end.
Hold the rope 50cm from the rope guide, gently release the reel to wind the rope until the knot reaches the rope guide.

Recoil Starter Disassembly repair

⚠ Wear protective goggles before disassembly.

⚠ Spring pull is maximized while the rope is fully pulled out; do not release suddenly.

Tools: Long-nose pliers, Retaining-ring pliers, Protective goggles

Unhook the spring: pull out all rope, align rope guide and knot inside reel, hold reel with thumbs, pull knot from reel.
Slowly rewind the rope while controlling the reel with both thumbs.
Remove the retaining-ring C with ring pliers and remove friction plate and ratchet beginning at the top.
Move the reel left and right 1/4 turns several times, then slowly lift the reel from the case.
Repeat if the spiral spring sticks out.

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 Subaru EX21?

The Subaru EX21 engine has an oil capacity of 0.63 liters.

What is the displacement of the Subaru EX21?

The Subaru EX21 has a displacement of 0.211 liters.

Which generators use the Subaru EX21 engine?

The Subaru EX21 powers 1 generator set(s), including Cummins/Onan P3200i.

What is a common problem with the Subaru EX21 engine?

A commonly reported issue on generators using the Subaru EX21 is: When No Electricity Is Generated at Receptacle. Fix: Check fuel level. Check to make sure generator is not connected to an appliance. Check spark plug for loose spark plug cap. Check spark plug for contamination. Check engine oil level. Check if the recommended spark plug would be adopted. If empty, refill fuel tank making sure not to overfill. If connected, turn off the power switch on the connected appliance and unplug. If loose, push spark plug cap back into place. Remove spark plug and clean electrode. If the engine oil level is low, add the oil to the upper level line on the oil gauge. If not, replace with the recommended spark plug. If the recommended spark plug is not available by all means, make sure to replace with equivalent one of resistance type..