Product Description
The Cummins 4938948 OEM Crankshaft Thrust Bearing is a genuine factory thrust washer designed to control endplay in all 1989–2018 5.9L and 6.7L Cummins B-Series / ISB engines. Excessive thrust wear can cause crankshaft movement, torque converter misalignment, transmission damage, and premature main bearing failure. Installing genuine Cummins thrust bearings ensures correct material hardness, proper oil-channel geometry, and long-life durability for stock or performance applications.
Whether you're rebuilding a 6BT, upgrading a 24-Valve ISB, or refreshing a 6.7L long block, the 4938948 thrust bearing provides OE-level crankshaft stability and precise axial control. Never substitute generic aftermarket thrust washers—Cummins metallurgy and tolerances are vital for long-term reliability.
Fitment
- 1989–1998 5.9L 12-Valve Cummins (6BT)
- 1998.5–2002 5.9L 24-Valve ISB Cummins
- 2003–2007 5.9L Common Rail Cummins
- 2007.5–2018 6.7L Cummins ISB
- Industrial / agricultural B-Series engines (verify via ESN)
Note: Always verify thrust bearing width and configuration by engine serial number (ESN) during rebuilds.
Cross-Reference (Cummins-Only)
Common complementary Cummins rebuild components:
• Cummins 3904409 OEM Valve Stem Guide – 51.75mm
• Cummins 3904408 OEM Valve Stem Guide – 60.50mm
• Cummins 3900267 Tappet Cover Bolt Grommet Seal
FAQ
What does the Cummins 4938948 thrust bearing do?
This bearing limits crankshaft endplay, preventing forward/backward movement that can damage the crank, transmission, or main bearings.
Is this thrust bearing used on both 5.9L and 6.7L Cummins engines?
Yes. It fits 1989–2018 B-Series/ISB engines that call for the 4938948 thrust bearing design.
Should thrust bearings be replaced during an engine rebuild?
Absolutely. Cummins recommends replacing thrust bearings whenever the crankshaft is removed or if endplay exceeds service limits.
Can excessive thrust wear cause transmission issues?
Yes. Too much crank movement can misalign the torque converter, damage the pump, and cause severe transmission problems.
Do I need to measure crankshaft endplay after installing this?
Yes. Setting and verifying proper endplay is a required step when replacing thrust bearings.
Specifications for cummins 4938948
| Specification | Value |
|---|---|
| Brand | Cummins Genuine Parts |
| Part Number | 4938948 |
| Component Type | Crankshaft Thrust Bearing |
| UPC | Not Published |
| GTIN | Not Published |
| Cross Reference | Fits 5.9L & 6.7L thrust-bearing main locations; cross-references earlier Cummins thrust washer engineering numbers (ESN dependent). |
| E-Codes | N/A |
| Shipping Weight | 0.15 lbs |
| Package Dimensions | 2 x 2 x 1 in |
| Prop 65 Warning | Not Applicable |
