Product Description
Genuine Cummins
Cummins 4938948 — Crankshaft Thrust Bearing (STD)
MPN: 4938948 | Also Known As: thrust washer, thrust main bearing | Size: Standard (STD)
Why This Part
- ✓ Controls crankshaft endplay to protect the block, crank, and transmission interface.
- ✓ OE metallurgy & geometry for long bearing life and correct oil film.
- ✓ Direct-fit for B-Series ISB/QSB 5.9L & 6.7L applications (see fitment).
- ✓ Standard size (STD)—use oversize only if a line-bore/machining calls for it.
OE Fit STD Size 1 Set Per Engine
Quick Specs
| Type | Crankshaft thrust bearing (pair) |
|---|---|
| OE Part # | 4938948 |
| Engine Families | Cummins ISB/QSB (B-Series) 5.9L & 6.7L |
| Qty Required | 1 per engine (upper/lower thrust faces) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–2002 | 5.9L Cummins B-Series (12V/24V) | Ram 2500/3500 |
| 2003–2007 | 5.9L ISB (24V Common-Rail) | Ram 2500/3500 |
| 2007.5–2018 | 6.7L ISB (24V Common-Rail) | Ram 2500/3500 |
Industrial/Off-Highway: Common on ISB/ISBE/QSB 5.9 & 6.7 platforms—verify by ESN.
Often Paired With
- Main Bearing Set: select STD/oversize per crank & block measurements
- Rear Main Seal: Cummins 5259499 (typical)
- Assembly Lube & Plastigage: to verify clearances/endplay
What’s In The Box
- (1) Genuine Cummins Crankshaft Thrust Bearing Set (4938948)
- Other bearings/seals sold separately
Install Tips
- Measure crankshaft endplay; compare to Cummins spec before/after install.
- Lubricate faces generously; ensure correct orientation (oil grooves).
- Torque main caps to spec and re-check endplay; investigate out-of-spec results.
FAQ
IS 4938948 A STANDARD-SIZE THRUST BEARING?Yes—4938948 is the STD (standard) thrust bearing. Oversize thrust options (e.g., +0.25mm, +0.50mm) use different part numbers.
WHAT ENGINES DOES IT FIT?It’s used across Cummins B-Series ISB/ISBE/QSB (5.9L & 6.7L) applications, including Ram 2500/3500 model years noted above (verify by ESN).
DO I NEED MACHINE WORK TO INSTALL THIS?No—STD size installs without machining if components are within spec. Always measure endplay and inspect thrust faces.
SHOULD I REPLACE THE MAIN BEARINGS TOO?Recommended during bottom-end service. Choose bearing sizes based on crank/block measurements and wear pattern.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 4938948 for proper fit, material, and longevity.
