The Cummins/Onan 4BTA 3.9-G4 is a 3.92 L 4-cylinder turbocharged engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the C80D6 and C90D6. It holds 7.9 L (2.1 gal) of coolant.
Also known as: Cummins 4BTA 3.9-G4
Part of the Cummins/Onan 4BTA3.9 engine family — 8 variants share parts & fitment.
| Coolant capacity | 7.9 L |
|---|---|
| Displacement | 3.92 L |
| Cylinders | 4 |
| Aspiration | Turbocharged |
| Rated speed | 1800 rpm |
How to read your Cummins/Onan engine serial & model number →
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | — | ||||
| Fuel filter | — | ||||
| Oil filter | — | ||||
| Battery | Battery capacity (1x) 75 A/h | — | |||
| Belt | — | ||||
| Coolant | 18.0 l | — | |||
| Oil | 10.9 l | — | |||
| Spark plug | — |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
| Part # | Description | Category |
|---|---|---|
| 0140-3550 | Air Cleaner Element | Air filter |
| 0140-3553 | Air Cleaner (Heavy Duty) | Air filter |
| 0140-3590 | Element Air Cleaner | Air filter |
| 0140-3880 | Element Air Cleaner (Safety) | Air filter |
| 0133-0228 | Heater Kit (Alternator 240V) | Alternator |
| 0133-0229 | Heater Kit (Alternator 110V) | Alternator |
| FS3345 | Fuel - Filter | Fuel filter |
| 0501-0830 | Line - Oil (5/8" 15.9 Bore) | Hose |
| 0501-0841 | Line - Fuel | Hose |
| 0501-0842 | Line - Fuel | Hose |
| 0503-2462 | Hose | Hose |
| 0503-2466 | Hose - Air | Hose |
| 0503-2474-12 | Hose - Steam | Hose |
| 0503-2474-25 | Hose - Steam | Hose |
| 0503-2542 | Elbow - Hose | Hose |
| 0541-1115 | Hose Kit (c/w Clamps) | Hose |
| LF1251 | Oil - Filter | Oil filter |
| 0102-1448-02 | Adapter - Oil Drain | Service part / kit |
| 0130-6000 | Fan - Radiator | Service part / kit |
| 0159-1552 | Cap-Filler (fuel tank) | Service part / kit |
| 0333-0690 | Heater-Engine Coolant-240v. | Service part / kit |
| 0333-0699 | Heater-Engine Coolant-120v. | Service part / kit |
| 0416-1208 | Battery | Service part / kit |
| 0504-0254 | Valve - Gate (M18 x 1.5) | Service part / kit |
| 0541-1119 | Radiator Cap | Service part / kit |
| 0541-1120 | Drain Valve | Service part / kit |
| 0150-2201 | Speed Sensor - Magnetic | Sensor |
| 0159-1619 | Indicator Fuel (230 LG) | Sensor |
| 0193-0444 | Sender - Oil Pressure | Sensor |
| 0193-0468 | Sender - Low Coolant | Sensor |
| 0193-0529-01 | Sensor - Temperature | Sensor |
| 0309-0707-01 | Fuel Level Switch | Sensor |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.
The Cummins/Onan 4BTA 3.9-G4 has a displacement of 3.92 liters with 4 cylinders.
The Cummins/Onan 4BTA 3.9-G4 powers 2 generator set(s), including Cummins/Onan C80D6, Cummins/Onan C90D6.