The Subaru Robin 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
| Oil capacity | 0.63 L |
|---|---|
| Coolant capacity | 25.3 L |
| Displacement | 0.211 L |
| Aspiration | Air-Cooled 4-stroke OHC Gasoline |
Compiled from service & troubleshooting documentation across every generator set that uses the Subaru Robin EX21.
| 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.
| 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.
| Fluid | Grade | Standard | Ambient | 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.
| 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.
⚠ 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
⚠ An inaccurate circuit tester may give erroneous readings.
Tools: Circuit tester
⚠ Failure to reattach foam rubber linings will result in poor performance and durability.
⚠ Use caution not to break the gasket.
Tools: 10mm Box wrench
⚠ Electric wires are still connected to the control panel; do not separate the control panel forcibly.
Tools: Screw driver, Nipper
Tools: 12mm Box wrench
Tools: Flywheel holder (33B9990101)
Tools: Flywheel holder (33B9990101), Socket wrench, Flywheel puller (available on market)
Tools: 10mm Box wrench
⚠ Do not release pressure on the reel while winding the spiral spring; sudden rewinding may occur.
⚠ Wear protective goggles before assembly.
Tools: Protective goggles
⚠ 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
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.
The Subaru Robin EX21 engine has an oil capacity of 0.63 liters.
The Subaru Robin EX21 has a displacement of 0.211 liters.
The Subaru Robin EX21 powers 1 generator set(s), including Cummins/Onan P3200i.
A commonly reported issue on generators using the Subaru Robin EX21 is: Unit Runs Then Surges. Cause: Loose or worn spark plug leads.. Fix: Check spark plug leads at spark plug & ignition coil..