Product Description
CUMMINS 3904408 OEM VALVE STEM GUIDE (INTAKE, THICK WALL 60.50MM) – 5.9L 12V 6BT (1989–1998)
The Genuine CUMMINS 3904408 OEM Intake Valve Stem Guide is a thick-wall, precision-machined guide designed for factory-correct stem support on all 1989–1998 5.9L 12-valve 6BT engines. Valve guides play a critical role in stabilizing valve motion, maintaining correct stem lubrication, and preventing premature seat wear. If you're rebuilding a 6BT cylinder head or refreshing a high-mileage engine, replacing worn guides is essential for valvetrain accuracy, smoother operation, and extended engine life.
This Cummins intake valve guide is engineered with thick-wall construction for durability, proper thermal expansion characteristics, and tight dimensional control. It installs into the OE cylinder head with standard press-fit tooling and restores factory valve-to-guide clearance.
Pair this guide with other genuine Cummins valvetrain components such as the CUMMINS 3908621 Intake Valve and the CUMMINS 3900268 Valve Stem Seal to complete your cylinder head rebuild.
Fitment
- Engine: 5.9L Cummins 12-Valve 6BT
- Years: 1989–1998 (Dodge Ram & industrial 6BT applications)
- Position: Intake valve stem guide
- Style: Thick wall – 60.50mm
Cross-Reference & Compatible Cummins Parts
- CUMMINS 3908621 OEM INTAKE VALVE – 5.9L 12V 6BT
- CUMMINS 3900268 OEM VALVE STEM SEAL – 5.9L 12V
- CUMMINS 3908620 OEM EXHAUST VALVE – 5.9L 12V 6BT
Related Cummins references: 3904408 (intake guide), 3904407 (exhaust guide), 3900268 (seal), 3908621 (intake valve).
Installation Notes
- Guides require press-fit installation; professional machine shop service recommended.
- Always measure and verify valve-to-guide clearance after installation.
- Resurface or blend the seat area as needed after guide replacement.
Specifications for cummins 3904408
| Attribute | Value |
|---|---|
| Brand | Cummins (Genuine OEM) |
| Part Number | 3904408 |
| Component Type | Valve Stem Guide – Intake |
| Construction | Thick Wall – 60.50mm |
| Engine Compatibility | 5.9L 12-Valve Cummins 6BT (1989–1998) |
| Cross Reference | 3904407 (exhaust guide), 3900268 (seal), 3908621 (intake valve) |
| GTIN | Not published |
| UPC | Not published |
| Shipping Weight | Approx. 0.10 lb |
| Shipping Method | Standard ground |
| E-Codes | Used across 6BT emissions groups; verify per application |
| Prop 65 | WARNING: Cancer & reproductive harm — www.P65Warnings.ca.gov |
Frequently Asked Questions
IS THIS THE CORRECT INTAKE VALVE GUIDE FOR MY 5.9L 12V 6BT?
Yes — CUMMINS 3904408 is the correct thick-wall intake guide for most 1989–1998 12-valve 6BT engines. Always confirm by engine serial number for accuracy.
SHOULD I REPLACE ALL GUIDES DURING A CYLINDER HEAD REBUILD?
Yes. Even slight wear affects valve control. Replacing all guides ensures consistent clearances and extends cylinder head life.
DO I NEED MACHINE SHOP SERVICES?
Yes. Valve guide installation requires precision press work and reaming/honing to achieve correct valve stem clearance.
WHAT VALVES AND SEALS MATCH THIS GUIDE?
The correct Cummins companions are the 3908621 intake valve and the 3900268 valve stem seal.
