Maintenance schedule
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Oil filter | Full flow, cartridge | — | |||
| Oil | Gear | 4.55 qts. | — |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
The Generac 3.9 GN is a 3.9 L 6-cylinder naturally aspirated engine rated at 1800 rpm. It powers generator sets from Generac, including the 3.9GN and Home Standby - 40. It holds 4.55 L (1.2 gal) of oil and 5.6 L (1.5 gal) of coolant.
Also known as: GENERAC 3.9 GN
Part of the Generac 3.9L engine family — 3 variants share parts & fitment.
| Oil capacity | 4.55 L |
|---|---|
| Coolant capacity | 5.6 L |
| Displacement | 3.9 L |
| Cylinders | 6 |
| Aspiration | Naturally Aspirated |
| Rated speed | 1800 rpm |
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Oil filter | Full flow, cartridge | — | |||
| Oil | Gear | 4.55 qts. | — |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
| Part # | Description | Category |
|---|---|---|
| 090635 | AIR CLEANER, 7-3/4 | Air filter |
| 0D58250477 | BELT, ALTERNATOR & OTHERS, 1140X2 | Belt |
| 0D58250250 | FUEL FILTER | Fuel filter |
| 0D58250251 | FUEL FILTER ASY | Fuel filter |
| 0D58250105 | GASKET KIT, ENG OVERHAUL | Gasket |
| 0D58250107 | GASKET, ROCKER COVER | Gasket |
| 0D58250112 | GASKET, CYL HEAD | Gasket |
| 0D58250121 | GASKET, CYL BLOCK FR PLATE | Gasket |
| 0D58250143 | OIL PAN, ENG | Gasket |
| 0D58250495 | GLOW PLUG | Glow plug |
| 0D58250256 | TUBE, FUEL LINE | Hose |
| 0D58250257 | TUBE, FUEL LINE | Hose |
| 0D58250448 | NOZZLE & HOLDER ASY, FUEL, INJ | Injector |
| 0D58250227 | OIL FILTER | Oil filter |
| 0D58250103 | SLEEVE & PISTON KIT (FOR ONE ENGINE) | Service part / kit |
| 0D58250139 | BEARING SET, CRKSHFT | Service part / kit |
| 0D58250211 | OIL PUMP ASY, ENG | Pump |
| 0D58250261 | PUMP ASY, INJ PUMP FUEL FEED | Pump |
| 0D58250266 | GOVERNOR ASY, INJ PUMP | Pump |
| 0D58250476 | WATER PUMP ASY | Pump |
| 0D58250127 | CAP, SEALING, D=40 | Seal |
| 0D58250142 | OIL SEAL, CRKSHFT, RR | Seal |
| 0D58250481 | THERMOSTAT KIT | Thermostat |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.
The Generac 3.9 GN engine has an oil capacity of 4.55 liters.
The Generac 3.9 GN has a displacement of 3.9 liters with 6 cylinders.
The Generac 3.9 GN powers 2 generator set(s), including Generac 3.9GN, Generac Home Standby - 40.