Product Description
Cummins 5259499 — Rear Main Crankshaft Oil Seal
MPN: 5259499 | Also Known As: rear main seal, crankshaft rear oil seal | Notes: Non-sleeved design with cardboard inner ring; for non-damaged crank surfaces.
Why This Part
- ✓ OE sealing performance to stop leaks at the rear crankshaft.
- ✓ Direct-fit across Ram 5.9L & 6.7L applications (1989–2018).
- ✓ Factory materials & lip profile for durability under heat and RPM.
- ✓ Non-sleeved style for good crank surfaces (repair-sleeve version available separately).
Quick Specs
| Type | Rear main crankshaft oil seal (non-sleeved) |
|---|---|
| OE Part # | 5259499 |
| Cross-References (ID only) | 4945960, 4988952, 3973745, 3933262, 3970548, 5405392 |
| Qty Required | 1 per engine (sold individually) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1993 | 5.9L B (12-Valve) | D/W 250 & 350 |
| 1994–2002 | 5.9L B/ISB (12V & 24V) | Ram 2500/3500 |
| 2003–2018 | 5.9L & 6.7L ISB (24V Common-Rail) | Ram 2500/3500 |
Notes: Coverage spans 1989–2018 Ram diesel platforms. Always verify by VIN/ESN and crank surface condition.
Often Paired With
- Rear Main Cover Gasket (’89–’02): 4947667
- Rear Main Cover Gasket (’03–’18): 5443388
- Install Tool: CTA 3880 rear main seal installer (or equivalent)
- Repair-Sleeve Version: Rear main seal w/ repair sleeve (use if crank surface is worn)
What’s In The Box
- (1) Genuine Cummins Rear Main Seal (5259499), non-sleeved
- Cover gasket, tool, and repair sleeve sold separately
Install Tips
- Inspect crank flange for grooves; use repair-sleeve variant if worn.
- Lightly oil lip; drive square to specified depth with proper installer.
- Clean bellhousing area; verify no oil leak at cam or upper cover before reassembly.
FAQ
WILL THIS FIT MY 1989–2018 5.9L/6.7L CUMMINS RAM?Yes—5259499 is the OE rear main seal across 1989–2018 5.9L & 6.7L Ram applications (verify by VIN/ESN and crank condition).
DOES THIS INCLUDE A REPAIR SLEEVE OR TOOL?No—this is the non-sleeved seal; use a repair-sleeve version if the crank surface is worn. The CTA 3880 installer tool is commonly used.
WHAT COVER GASKET DO I NEED?1989–2002 usually uses gasket 4947667; 2003–2018 typically uses 5443388. Always confirm by VIN/ESN.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 5259499 for proper fit and long-term sealing.
HOW DO I KNOW MY REAR MAIN SEAL IS LEAKING?Oil dripping from the bellhousing inspection area, clutch slip (manual), or oil contamination on flexplate/flywheel are common indicators.
