Product Description
Genuine Cummins
Cummins 3802565 — Engine Piston Kit (.040" / 1.00 mm) for 5.9L 12-Valve
MPN: 3802565 | Also Known As: piston & ring kit, oversize piston kit | Bowl Style: OE “Small Bowl” (12-valve)
Why This Part
- ✓ OE Cummins piston kit for factory reliability and compression.
- ✓ .040" (1.00 mm) oversize to match cylinders after boring/honing.
- ✓ Includes piston, rings, wrist pin, and retainers for one cylinder.
- ✓ Small-bowl 12V geometry for proper combustion and emissions.
OE Fit .040" Oversize Use 6 Per Engine
Quick Specs
| Type | Piston kit with rings, wrist pin & retainers |
|---|---|
| Oversize | .040" / 1.00 mm |
| OE Part # | 3802565 (small-bowl 12V) |
| Qty Required | 6 kits per engine (sold individually per cylinder) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1994–1998 | 5.9L 12-Valve (6BT) — “Small Bowl” | Ram 2500/3500 |
Compatibility Notes: Catalogs also list this piston kit for some 1991.5–1993 intercooled 5.9L applications. Always verify piston bowl style and ESN. This kit is not for 24-valve or common-rail engines.
Often Paired With
- Lower Engine Gasket Set: Cummins 3802376 (’89–’98 5.9L)
- Rod/Main Bearings: engine-build size to match your crank
- Ring Compressor & Micrometer: to set/end-gap and clearances
What’s In The Box
- (1) Piston w/ rings (.040"), wrist pin, and retainers (per cylinder)
Install Tips
- Bore/hone to spec; measure piston-to-wall and ring end-gaps.
- Confirm small-bowl orientation and piston protrusion; follow Cummins manual.
- Use assembly lube, stagger ring gaps, and torque fasteners to spec.
FAQ
HOW MANY KITS DO I NEED FOR A FULL REBUILD?You’ll need six kits—one per cylinder.
WHAT DOES .040" / 1.00 MM OVERSIZE MEAN?Your cylinders must be bored/honed .040" (1.00 mm) over standard to use these pistons/rings.
WHAT’S INCLUDED IN THE KIT?One piston, matched ring set, wrist pin, and pin retainers (per cylinder).
WILL THIS FIT 1991.5–1993 ENGINES?Some catalogs list it for 1991.5–1993 intercooled 5.9L, but bowl styles vary. Verify by ESN and piston bowl before ordering.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3802565 small-bowl .040" piston kit.
