Product Description
The CUMMINS 4089977 OEM PISTON KIT (.040 OVER) is a genuine Cummins-manufactured piston kit engineered specifically for the 5.9L ISB 305 HP common-rail diesel found in 2003 (HO) and early 2004 (Federal emissions) Dodge Ram 2500/3500 trucks. This is a .040" (1.00 mm) oversize piston kit — ideal for use after machining cylinders to .040" over bore. The kit includes piston, hardened wrist pin, pin retainers (circlips), and a matched piston ring set — sold individually (six required for a complete engine). As a genuine OEM part, the piston crown and skirt geometry are matched to the 305 HP ISB combustion profile for optimal combustion dynamics, longevity, and smooth operation under load.
Fitment / Application:
- Engine: 5.9L ISB 24-valve Common-Rail diesel, 305 HP configuration.
- Model Years: 2003 (HO) and early-2004 (Federal emissions) Dodge Ram 2500/3500.
- Quantity: Sold per piston — 6 required for a full rebuild.
- Not compatible with 2004 California-emissions trucks (non-305 HP). Always verify ESN / VIN / engine tag before ordering.
Includes:
- 1 × piston (0.040" / 1.00 mm oversize)
- 1 × hardened wrist pin
- 2 × pin retainers (circlips)
- 1 × piston ring set
Why This Piston Kit Matters:
- OEM-spec materials and machining ensure durability and long service life under heavy diesel loads. - Ideal for overbore rebuilds where cylinders are machined to .040" oversize — restores proper ring sealing and compression. - Maintains manufacturer-designed piston geometry for combustion efficiency and longevity.
- Full rebuild compliance: pair with correct rod & main bearings, head-gasket set, and torque plates for best results.
FAQ
WILL THIS FIT MY 2003–2004 5.9L CUMMINS?
This kit fits the 305 HP ISB calibration only — 2003 HO trucks and early-2004 Federal emissions trucks. It does not fit 2004 California-emissions trucks. Verify by VIN/ESN.
WHAT SIZE IS THIS PISTON KIT?
It’s a .040" over (1.00 mm) piston kit. Cylinders must be bored and honed to .040" oversize for correct fitment.
WHAT COMES IN THE KIT?
Piston, hardened wrist pin, pin retainers (circlips), and a matched piston ring set — sold individually, so order 6 for a complete engine.
DO YOU OFFER OTHER OVERSIZES / STANDARD SIZE?
Yes — for .020" over bore use kit part # 4089976, and for standard bore use part # 4089950. Contact us or check our catalog.
For other oversize options, see: CUMMINS 4089976 OEM PISTON KIT (.020 OVER) – ISB 5.9L 305 HP
CUMMINS 4089950 OEM PISTON KIT (STANDARD) – ISB 5.9L 305 HP
| Specifications for CUMMINS 4089977 | |
|---|---|
| Part Number | 4089977 |
| Kit Type | .040" / 1.00 mm Oversize Piston Kit |
| Engine | 5.9 L ISB 24-Valve Common-Rail, 305 HP |
| Contents | Piston, Wrist Pin, Pin Retainers (circlips), Piston Ring Set (single cylinder) |
| Quantity Required | 6 per engine (sold individually) |
| Package Dimensions | 5.00" (D) × 5.125" (W) × 4.88" (H) |
| Package Weight | ≈ 3.1 lb :contentReference[oaicite:9]{index=9} |
| Cross Reference | 4089977 |
| Shipping Info | Free Shipping (per store policy) / Ships individually |
| GTIN / UPC | 4089977 |
| E-Code / Prop 65 Warning | — / No Prop 65 warning listed |
