The Cummins/Onan 4BT3.9 engine line groups 6 variant designations. Parts and fitment are pooled here so a cross-reference found on one variant surfaces for the whole family.
| Part # | Description | Category |
|---|---|---|
| 187-0008 | Belt, Drive | belt |
| 353-0094-01 | Connector Housing and Contact Pins, 8 Pin (Less Pins) | connector |
| 187-0011 | Filter, Fuel | fuel_filter |
| 187-0012 | Gasket, Cover - Valve | gasket |
| 503-0365 | Heater, Engine - 750 Watt (120 volt) | heater |
| 140-2164 | Nut, Square (1/4-20) | nut |
| 187-0015 | Filter, Oil | oil_filter |
| 187-0020 | Pump, Injection | pump |
| 323-1200 | Resistor, Fixed, Wirewound AR | resistor |
| 323-1306 | Screw, Cap - Hex Head (1/4-20 x 1/2") | screw |
| 750-1010 | Screw, Machine - Fillister Head (1/4-20 x 1") | screw |
| 800-0048 | Screw, Cap - Hex Head (3/8 - 16 X 3/4") | screw |
| 405-3826-01 | Support, Engine - Screw, Cap - Hex Head (M12 x 1.75 x 65mm) | support |
| 309-0269 | Switch, Temperature - Screw, Machine - Round Head (#8-32 x 1/4") | switch |
| 309-0561 | Switch, Temperature - Washer, Lock (#10) | switch |
| 332-2921 | Clamp, J | switch |
| 187-0009 | Thermostat | thermostat |
| 821-0018 | Thermostat (Includes Plugs) | thermostat |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.