The Cummins/Onan 4B3.9 is an engine. It powers generator sets from Cummins/Onan, including the 35 DGBB, 37 DGBA, 40 DGBC and DGBB. It holds 11 L (2.9 gal) of oil and 21 L (5.5 gal) of coolant.
Also known as: Cummins 4B3.9
Part of the Cummins/Onan 4B3.9 engine family — 3 variants share parts & fitment.
| Oil capacity | 11.0 L |
|---|---|
| Coolant capacity | 21.0 L |
Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan 4B3.9.
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | The filter element should be replaced yearly or sooner if the service indicator button pops up indicating air restriction. | — | 8760 hr | find | |
| Fuel filter | — | 50 hr | find | ||
| Oil filter | — | 500 hr | find | ||
| Belt | Cummins engine Operation and Maintenance Manual | — | find | ||
| Coolant | Cummins engine Operation and Maintenance Manual | 21.0 Gal (L) | — | ||
| Coolant filter | — | find | |||
| Oil | Change the oil and filter at the intervals recommended in the maintenance table. | 12.0 | — | 500 hr |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
| Part # | Description | Category |
|---|---|---|
| 928-0502B | other_service | |
| 928-0506 | other_service | |
| 960-0135 | other_service | |
| 960-0504A | other_service | |
| 960-0505 | other_service | |
| 960-12 | other_service |
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 4B3.9 engine has an oil capacity of 11.0 liters.
The Cummins/Onan 4B3.9 powers 9 generator set(s), including Cummins/Onan 35 DGBB, Cummins/Onan 37 DGBA, Cummins/Onan 40 DGBC, Cummins/Onan DGBB, Cummins/Onan DGBC.
The Cummins/Onan 4B3.9 oil change interval is every 500 hours.
A commonly reported issue on generators using the Cummins/Onan 4B3.9 is: Over Current.