The Cummins/Onan B5.9 engine line groups 5 variant designations. Parts and fitment are pooled here so a cross-reference found on one variant surfaces for the whole family.
| Part # | Description | Category |
|---|---|---|
| RU5045 | Air Cleaner | air_filter |
| 4988274 | Alternator | alternator |
| 3288689 | Belt | belt |
| V70509 | Lube Oil | fluid |
| FS1251/FF42000 | Fuel Filter | fuel_filter |
| LF3959 | Lube Filter | lube_filter |
| 12.001-3678-000 | Lubricating Oil Pressure Gauge | other_service |
| 13.001-3901-000 | Battery A/B Switch | other_service |
| 14.001-3912-000 | ON/OFF Switch (AUTO/MANUAL) | other_service |
| 3305062 | Heater, 240V | other_service |
| 3315032 | Heater, 120V | other_service |
| 3885910 | Red Paint, Spray can | other_service |
| 5.001-2674-000 | True Warning Light | other_service |
| 6.001-3789-000 | Low Oil Pressure Warning Light | other_service |
| 7.001-3890-000 | Circuit Breaker | other_service |
| 8210G003-12VDC | 3/4" 12V solenoid | other_service |
| 8210G3-24VDC | 3/4" 24V solenoid | other_service |
| 3971603 | Starter 12V | starter |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.
This engine family also powers 10 generator set(s) on Facts About Generators.