Product Description
Cummins 3802423 — Piston Ring Set (.040" / 1.00 mm Oversize)
MPN: 3802423 | Also Known As: piston rings, ring set | Oversize: .040" (1.00 mm) | Platform: Cummins B/ISB 5.9L
Why This Part
- ✓ OE ring set for overbore rebuilds requiring .040" (1.00 mm) oversize.
- ✓ Restores compression and oil control on high-mile engines.
- ✓ Direct match to Cummins specs for B/ISB 5.9L pistons.
- ✓ Sold per-cylinder set — order 6 sets for a complete engine.
Quick Specs
| Type | Piston ring set (top/second/oil) for one piston |
|---|---|
| OE Part # | 3802423 |
| Oversize | .040" (1.00 mm) |
| Qty Required | 6 per engine (sold per cylinder) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–2002 | Cummins 5.9L B/ISB (12V 1989–1998; 24V 1998.5–2002) | Ram 2500/3500 |
Notes: This is an .040" oversize ring set for overbore rebuilds. Confirm cylinder bore, piston style, and ESN before ordering.
Often Paired With
- Other ring sizes: 3802421 (STD), 3802422 (.020" / 0.50 mm)
- Piston kits: STD / .020" / .040" to match bore
- Lower engine gasket set and head gasket
- Machine work: professional overbore/hone to spec, measure with torque plates
What’s In The Box
- (1) Genuine Cummins piston ring set for one cylinder (.040")
- Order quantity 6 for a full engine
Install Tips
- Verify piston/ring compatibility (keystone vs. square), end gaps, and orientation.
- Measure final bore with torque plates; set ring gaps per Cummins spec.
- Cleanliness is critical—scrub bores and pistons before assembly.
FAQ
WILL THIS FIT MY 1989–2002 5.9L CUMMINS RAM?Yes—this .040" ring set is for overbore rebuilds on B/ISB 5.9L 12V (’89–’98) and 24V (’98.5–’02). Always verify by ESN, piston style, and bore.
HOW MANY SETS DO I NEED?One set services one piston. Order 6 sets to re-ring the entire engine.
WHAT DOES .040" (1.00 MM) OVERSIZE MEAN?Your block must be bored/honed to the .040" oversize dimension and matched with .040" pistons. Rings alone won’t correct a worn standard bore.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3802423 ring set built to factory specifications.
WHAT IF I’M STILL STANDARD BORE?Use ring set 3802421 (STD) if your cylinders measure within standard limits. Consider 3802422 (.020") for minor overbores.
