Product Description
Genuine Cummins
Cummins 3800784 — Engine Piston Kit (.50 mm / 0.020" Over) for 5.9L ISB
MPN: 3800784 | Also Known As: piston kit, piston & rings set | Size: 0.50 mm over (.020")
Why This Part
- ✓ OE piston kit for accurate compression and durability on ISB 5.9L.
- ✓ .020" oversize (0.50 mm) for engines honed/bored during rebuild.
- ✓ Restores performance and blow-by control after wear.
- ✓ Built to Cummins specs for ring seal and long service life.
OE Quality 0.50 mm Over Sold Individually
Quick Specs
| Type | Engine piston kit (with rings & pin retainers) |
|---|---|
| Oversize | 0.50 mm (0.020") |
| OE Part # | 3800784 |
| Kit Contents | Piston, ring set, wrist pin, pin retainers (circlips) |
| Qty Required | Sold individually (1 cylinder); order 6 for a full 5.9L set |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1998.5–2002 | 5.9L ISB 24-Valve (VP44) — Standard Output | Ram 2500/3500 |
Industrial/Off-Highway: Used primarily on Tier 2 ISB/QSB 5.9 platforms; verify by ESN/CPL prior to ordering.
Often Paired With
- Overhaul sets / gasket kits (upper & lower)
- Main & rod bearings matched to your crank size
- Hone/boring & ring file per Cummins service procedure
What’s In The Box
- (1) Genuine Cummins piston kit 3800784 — .50 mm (.020") over
- Includes piston, ring set, wrist pin, and pin retainers
Install Tips
- Confirm cylinder bore finish and clearance for .020" oversize; measure ring end-gap.
- Verify piston orientation (markings) and oiling; torque per Cummins spec.
- Always match parts to your ESN/CPL; some HO variants differ.
FAQ
WILL THIS FIT MY 1998.5–2002 5.9L CUMMINS RAM?Yes—this .020" piston kit is listed for 1998.5–2002 5.9L ISB 24-valve (Standard Output). Always confirm by ESN/CPL.
WHAT’S INCLUDED IN EACH PISTON KIT?Each kit includes a piston, ring set, wrist pin, and pin retainers (circlips). Kits are sold per cylinder.
HOW MANY DO I NEED FOR A COMPLETE ENGINE?Order quantity 6 for a full set on a 5.9L inline-six.
IS .50 MM THE SAME AS .020" OVER?Yes—0.50 millimeter overbore equals approximately 0.020 inches.
DOES THIS FIT INDUSTRIAL ISB/QSB 5.9 ENGINES?Common on Tier 2 ISB/QSB 5.9 applications. Verify by ESN/CPL to confirm compatibility.
