Product Description
Cummins 3973511 — Engine Oil Fill Cap (w/ O-Ring Interface)
MPN: 3973511 | Also Known As: oil filler cap, oil fill cap | Common Cross-Refs: 68003321AA (Mopar); 3937759, 3968202, 3942135, 3944736, 3945254
Why This Part
- ✓ OE sealing to keep contaminants out and oil vapors in.
- ✓ Direct-fit for Ram 5.9L/6.7L ISB applications (see fitment).
- ✓ Durable OE construction for long service life.
- ✓ Works with factory cap O-ring 3973512 (sold separately).
Quick Specs
| Type | Engine oil filler cap |
|---|---|
| OE Part # | 3973511 |
| Related/O-ring | 3973512 (cap O-ring, sold separately) |
| Cross-Refs | 68003321AA; 3937759; 3968202; 3942135; 3944736; 3945254 |
| Qty Required | 1 per engine (sold individually) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1998.5–2002 | Ram 5.9L ISB (24V) | Ram 2500/3500 |
| 2003–2024 | Ram 5.9L/6.7L ISB (CR) | Ram 2500/3500 |
Notes: Geno’s Garage lists 3973511 for ’98.5–’25 5.9L/6.7L Rams, and Cummins’ 3973512 O-ring lists coverage through late-model years. Always confirm by VIN/ESN and cap style on late 6.7L trucks.
Often Paired With
- Oil cap O-ring: 3973512 (’98.5–present coverage)
- Fresh oil & filter after any oil system service
What’s In The Box
- (1) Genuine Cummins Engine Oil Fill Cap (3973511)
- O-ring sold separately (3973512)
Install Tips
- Replace the cap O-ring (3973512) if brittle, torn, or leaking.
- Wipe valve cover neck clean before seating the cap; hand-tighten only.
- If seepage persists, inspect O-ring groove and mating neck for damage.
FAQ
WILL THIS FIT MY 5.9L OR 6.7L CUMMINS RAM?Yes—3973511 is listed for ’98.5–present Ram 5.9L/6.7L by multiple retailers; verify by VIN/ESN and cap style on late 6.7L trucks.
WHAT O-RING DOES THIS CAP USE?Use Cummins O-ring 3973512 (widely listed for ’98.5–present Ram 5.9L/6.7L).
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3973511 for proper sealing and durability.
WHAT ARE COMMON CROSS REFERENCES?Mopar 68003321AA; Cummins 3937759, 3968202, 3942135, 3944736, 3945254.
DOES THIS PART ALSO FIT INDUSTRIAL ISB/QSB?Yes—Cummins indicates usage on Tier 3 5.9L ISB/QSB industrial engines; verify by ESN.
