Product Description
Cummins 3929457 — Multi-Purpose O-Ring Seal (B/ISB/QSB)
MPN: 3929457 | Also Known As: seal, O-ring | Cross-Refs: M-3929457 (Interstate-McBee), FP-3929457 (FP Diesel)
Why This Part
- ✓ OE sealing integrity to prevent leaks and maintain oil/coolant system pressure.
- ✓ Direct-fit replacement O-ring for B/ISB/QSB applications (see fitment notes).
- ✓ Durable elastomer material for heat and fluid resistance.
- ✓ Budget-friendly part that prevents bigger failures from minor leaks.
Quick Specs
| Type | O-ring seal (multi-purpose) |
|---|---|
| OE Part # | 3929457 |
| Common Uses | Seen in oil cooler assemblies and oil pressure regulator interfaces on B/ISB/QSB engines (verify by ESN/IPL) |
| Qty Required | Varies by service location; sold individually |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–2002 | Ram 5.9L B/ISB (12V & 24V) | Ram 2500/3500 |
Notes: This O-ring is also used across various B/ISB/QSB industrial engines and some later ISB/6.7L locations. Always confirm by Engine Serial Number (ESN) and illustrated parts list (IPL) before ordering.
Often Paired With
- Oil cooler gaskets/seals (’94–’02 5.9L): 4932124 (cooler→block), 3942915 (cooler→filter)
- Oil pressure regulator components as specified by ESN/IPL
- Fresh oil & filter after sealing work to flush debris
What’s In The Box
- (1) Genuine Cummins O-Ring Seal (3929457)
Install Tips
- Match by ESN and location in the Cummins IPL; do not assume by appearance alone.
- Lightly oil the O-ring; avoid twisting; torque mating hardware to spec.
- Warm up and inspect for seepage; recheck after initial heat cycle.
FAQ
WILL THIS FIT MY 1989–2002 5.9L CUMMINS RAM?Yes—this O-ring is commonly used on 1989–2002 5.9L applications. Always verify exact location by ESN/IPL.
WHAT SYSTEMS USE THIS O-RING?Typical uses include oil cooler assembly interfaces and oil pressure regulator sealing on B/ISB/QSB engines (confirm by ESN).
IS THIS A GENUINE CUMMINS PART?Yes—this listing is for genuine Cummins 3929457. Aftermarket equivalents include FP-3929457 and M-3929457.
HOW MANY DO I NEED?Quantity varies by service location. Consult the IPL for your ESN to determine the count needed for the job.
CAN THIS FIT 6.7L ENGINES?Some ISB/QSB 6.7L industrial and automotive locations use this size O-ring. Verify by ESN before ordering.
