The Cummins/Onan 4BTA3.9-G3 is a 3.9 L 4-cylinder turbocharged and jacket water aftercooled engine rated at 1500 rpm, producing up to 80.6 kW. It powers generator sets from Cummins/Onan, including the DGCG. It holds 10.9 L (2.9 gal) of oil.
Also known as: Cummins 4BTA3.9-G3
Part of the Cummins/Onan 4BTA3.9 engine family — 5 variants share parts & fitment.
| Oil capacity | 10.9 L |
|---|---|
| Displacement | 3.9 L |
| Cylinders | 4 |
| Aspiration | Turbocharged and Jacket Water Aftercooled |
| Rated speed | 1500 rpm |
| Gross power | 80 kW |
Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan 4BTA3.9-G3.
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | Maximum Air Cleaner Restriction: 25.0 in. H2O (6.2 kPa) | — | find | ||
| Fuel filter | — | find | |||
| Oil filter | Lube Oil Filter Types: Single spin-on canister, full flow | — | find | ||
| Oil | Lube Oil Filter Types: Single spin-on canister, full flow | 10.9 L | — |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
| Part # | Description | Category |
|---|---|---|
| 2.4L | Engine | engine |
| 285542 | Gasket. manifold | gasket |
| 265484 | Line. flex. fuel, 41" | hose |
| 266110 | Line, flex. fuel, 50” | hose |
| 271500 | Line. flex. fuel, 22” | hose |
| 285498 | Hose, molded | hose |
| 285722 | Hose, upper molded | hose |
| 285957 | Line. flex. fuel | hose |
| X-797-2 | Hose, flex | hose |
| A046K020 | Oil Filter | oil_filter |
| 0L2090-C | 60 kW (2.4 L) | other_service |
| A-290538 | Block heater | other_service |
| A-290885 | Heater, block (240V) | other_service |
| 240976 | Switch, high temperature 268298 Sender, temperature | sensor |
| 241481 | Switch, high temperature 268298 Sender, water temperature | sensor |
| 268298 | Sender, water temperature gauge | sensor |
| 290090 | Switch, low water temperature | 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 4BTA3.9-G3 engine has an oil capacity of 10.9 liters.
The Cummins/Onan 4BTA3.9-G3 has a displacement of 3.9 liters with 4 cylinders.
The Cummins/Onan 4BTA3.9-G3 powers 1 generator set(s), including Cummins/Onan DGCG.
A commonly reported issue on generators using the Cummins/Onan 4BTA3.9-G3 is: Over Current.