Product Description
Cummins 3802421 — Piston Ring Set (Standard Bore) for B-Series 5.9L
MPN: 3802421 | Also Known As: piston rings, ring set, STD bore | Cross-Refs (ID only): 3802050, 3802056, 3802230, 3802746
Why This Part
- ✓ OE sealing and oil control to restore compression and reduce blow-by.
- ✓ Direct-fit for B-series 5.9L builds (see fitment table below).
- ✓ Standard (STD) bore set for unbored cylinders—measure and verify size.
- ✓ Durable OE materials for long service life.
Quick Specs
| Type | Piston ring set (STD bore) |
|---|---|
| OE Part # | 3802421 |
| Quantity | Complete set for 6 pistons (sold as one engine set) |
| Platform | Cummins B-series 5.9L (see Automotive Fitment) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1998 | 5.9L 12V 6BT (Mechanical) | Ram 2500/3500 |
| 1998.5–2002 | 5.9L 24V ISB (VP44) | Ram 2500/3500 |
Industrial/Off-Highway: Used primarily on non-certified (pre-EPA) 5.9L B-series engines; always verify by ESN and bore size.
Compatibility Notes:
- For standard bore cylinders. If your block was bored/honed, order the correct oversize.
- Verify piston groove style and ESN during 1998.5–2002 transitions.
- When in doubt, measure bore and consult Cummins QuickServe with your ESN.
Often Paired With
- Piston ring compressor & cylinder hone for correct installation and finish
- Head gasket set (5.9L 1989–2002)
- Assembly lube and break-in oil
What’s In The Box
- (1) Genuine Cummins Piston Ring Set (3802421), complete for 6 pistons (STD bore)
- Installation hardware/tools not included
Install Tips
- Measure cylinder bores; confirm STD vs. oversize before opening packaging.
- File-fit as required; clock ring end gaps per Cummins procedure.
- Verify crosshatch and cleanliness; change oil and filter after break-in.
FAQ
WILL THIS FIT MY 1989–2002 5.9L CUMMINS RAM?Yes—this STD-bore ring set is used across 12V (’89–’98) and 24V VP44 (’98.5–’02) builds. Always confirm by ESN and bore size.
IS THIS A FULL ENGINE SET OR ONE CYLINDER?It’s a complete set for six pistons (one engine). If you need oversize, select the correct OS set instead.
WHAT SIZE IS THIS?Standard (STD) bore. Measure your block—many rebuilds require +0.020" (+0.5mm) or other oversizes.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3802421 with proper material spec and ring geometry.
DOES THIS ALSO FIT 4BT/INDUSTRIAL APPLICATIONS?It’s used primarily on non-certified B-series engines; verify by ESN for 4BT and off-highway applications.
