Product Description
CUMMINS 3800784 OEM ENGINE PISTON KIT (.020) – 5.9L ISB (1998.5–2002)
The genuine CUMMINS 3800784 OEM Engine Piston Kit (.020) is engineered for precise factory-spec restoration of the 5.9L ISB found in 1998.5–2002 Dodge Ram trucks. This kit delivers OE reliability for VP44-equipped engines, ensuring proper combustion sealing, reduced blow-by, and long service life. Whether you’re performing a complete overhaul or replacing a damaged cylinder, this .020 oversize Cummins piston kit provides unmatched OE fitment and durability.
Each kit includes the OEM piston, piston rings, wrist pin, and pin retainers, allowing engine builders to maintain the integrity and longevity expected from a genuine Cummins repair. Pair this piston with additional Cummins overhaul components such as the CUMMINS 3804896 connecting rod or the CUMMINS 3802375 main bearing set to complete a professional-grade rebuild.
Key Features
- Genuine Cummins .020 Oversize Piston Kit – exact fit for ISB rebuilds.
- Designed for VP44 24-valve engines (1998.5–2002 Ram Cummins).
- Includes OEM piston, rings, wrist pin, and retainers.
- Meets factory metallurgy, coating, and machining standards for long-term durability.
- Perfect for performance refresh or stock rebuild where OE quality is required.
Fitment Details
- Engine: 5.9L Cummins ISB (24-valve)
- Years: 1998.5–2002
- Fuel System: VP44-equipped ISB
- Oversize: .020 (0.50mm)
- Common Applications: Dodge Ram 2500/3500
Always confirm piston size by measuring cylinder wear or consulting machine shop recommendations.
Cross-Reference & Companion Cummins Parts
- CUMMINS 3804896 OEM CONNECTING ROD – 5.9L ISB
- CUMMINS 3802375 MAIN BEARING SET – 5.9L
- CUMMINS 3950661 ROD BEARING SET – STANDARD
- VIEW ALL GENUINE CUMMINS PARTS
Installation Notes
- Confirm cylinder bore size (.020 oversize required).
- Verify ring end gaps according to Cummins specifications.
- Lubricate wrist pin and skirt before installation.
- Have cylinders properly honed for oversize pistons.
Specifications for cummins 3800784
| Attribute | Value |
|---|---|
| Brand | Cummins (Genuine OEM) |
| Cummins Part Number | 3800784 |
| Oversize | .020 (0.50mm) |
| Engine Compatibility | 5.9L ISB (1998.5–2002), VP44 injection system |
| Included Components | OEM piston, rings, wrist pin, retainers |
| UPC | 3663872109216 |
| GTIN | 3663872109216 |
| Shipping Weight | Approx. 2.5–3.0 lbs |
| Typical Shipping Method | Standard ground shipping from CPP Diesel |
| Cross Reference | 3800784RX, 3800783 (.010), 3800785 (.030) |
| E-Codes | Applicable to ISB emissions families (consult Cummins ESN-specific data) |
| Prop 65 Warning | WARNING: This product contains materials known to the State of California to cause cancer and reproductive harm. See www.P65Warnings.ca.gov. |
| Country of Origin | As labeled by Cummins (varies by batch) |
Frequently Asked Questions
IS THIS PISTON KIT REALLY .020 OVERSIZE?
Yes. CUMMINS 3800784 is a true .020" oversize piston kit for ISB engines that require cylinder machining.
CAN I USE THIS IN MY 24-VALVE 1998.5–2002 RAM?
Yes. This piston kit is specifically designed for the VP44-fueled 24-valve 5.9L ISB engine.
DOES THIS INCLUDE PISTON RINGS?
Yes. Each Cummins 3800784 kit includes matched rings, wrist pin, and retainers.
SHOULD I HONE THE CYLINDER BEFORE INSTALLING?
Yes. Proper honing is required for correct ring sealing and piston fitment.
CAN I MIX OVERSIZES IN THE SAME ENGINE?
Yes, but each cylinder must be measured and machined individually. Never install an oversize piston into a standard bore.
