Product Description
Interstate-McBee M-3921640 Valve Stem Seal – 89–98 5.9L Cummins 12-Valve
OE-style valve stem seal for the 1989–1998 Dodge Ram 2500/3500 equipped with the 5.9L Cummins 12-valve (6BT). Designed to control valve guide oiling and reduce consumption. Sold individually.
- Direct replacement: Built to OE form and function for reliable sealing.
- Durable materials: Resists heat, oil, and fuel vapors found in diesel applications.
- Service friendly: Ideal for top-end refreshes and head rebuilds.
- Value: Interstate-McBee quality at an aftermarket price.
Specifications
| Brand | Interstate-McBee |
| Part Number | M-3921640 |
| OEM Reference | Cummins 3921640 |
| Sold As | Each (1 valve stem seal) |
| Application | Valve stem seal (valvetrain) |
What’s Included
- (1) Valve stem seal, P/N M-3921640
Vehicle Fitment
Always verify by engine serial number (ESN) when possible.
- Dodge Ram 2500/3500 5.9L Cummins (12-valve 6BT)
- Model Years: 1989–1998
- Additional B-Series engines where Cummins 3921640 is specified (confirm by ESN).
Quantity Guidance
Quantity required can vary by build. Many 12-valve 5.9L applications use seals on intake valves only. Confirm your configuration by ESN or service manual before ordering.
Recommended/Related Parts
- Interstate-McBee M-3900250 Valve Keeper (Locks)
- Interstate-McBee M-3900299 Valve Spring Retainer
- Interstate-McBee M-3802355 Intake Valve Kit
- Interstate-McBee M-3802356 Exhaust Valve Kit
- Interstate-McBee M-3283335 Head Gasket (12-Valve)
Install Notes
- Use the correct seal driver; avoid nicking the seal lip.
- Lightly oil the valve stem and seal before installation.
- Follow Cummins service procedures for spring compression and retainer/keeper handling.
FAQ
Will this fit my 1989–1998 5.9L Cummins?
Yes—this part number is used on 12-valve 5.9L Cummins applications noted above. For edge cases, verify by ESN.
How many should I order?
Confirm by ESN; many 12-valve builds use seals on intake valves only. Order the appropriate quantity for your configuration.
Can I reuse old seals?
Reusing old seals is not recommended. Replace during any head or top-end service for best results.
