The Cummins/Onan QSK78-G12 is a 78 L engine rated at 1800 rpm. It powers generator sets from Cummins/Onan.
Also known as: Cummins QSK78-G12
Part of the Cummins/Onan QSK78 engine family — 9 variants share parts & fitment.
| Displacement | 78.0 L |
|---|---|
| Rated speed | 1800 rpm |
How to read your Cummins/Onan engine serial & model number →
| Item | Action | Hours | Months | Notes |
|---|---|---|---|---|
| valve clearance | Check | 2000 hr | B-Series (4BT3.3): valve clearance checks not required for 2000 hours, twice the industry standard | |
| engine overhaul | Other | 20000 hr | QSK23-Series: expected life cycle to 20,000 hours before first overhaul |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Part # | Description | Category |
|---|---|---|
| 0140-3963 | Filter, Air - Standard Duty | Air filter |
| A034R952 | Filter, Air - Heavy Duty | Air filter |
| A034R957 | Element, Primary - Heavy Duty | Air filter |
| A034R963 | Secondary, Primary - Heavy Duty | Air filter |
| 5572840 | Cylinder Head Lifting Handle Kit | Service part / kit |
| 5573037 | Camshaft Removal & Installation Kit | Service part / kit |
| 908-0600 | Cummins QSK78 Series Engine Operation and Maintenance Manual | Service part / kit |
| A041X654 | Element, Replacement - Crankcase Breather | Service part / kit |
| APCH-1007-12 | Bulletin 5600277 | Service part / kit |
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 QSK78-G12 has a displacement of 78.0 liters.
The Cummins/Onan QSK78-G12 powers 1 generator set(s), including Cummins/Onan QSK78-G12.