Product Description
The CUMMINS 3904105 OEM EXHAUST VALVE SEAT (VALVE INSERT) is a genuine Cummins replacement component designed for 1989-1998 Dodge Ram 5.9L Cummins 12-valve diesel engines. This hardened valve seat insert is precision manufactured to restore proper valve sealing, heat transfer, and cylinder head performance during engine rebuilds and cylinder head repairs.
Exhaust valve seats are exposed to extreme combustion temperatures and can become worn, recessed, cracked, or damaged over time. Replacing worn valve seats with genuine Cummins components helps restore correct valve sealing, improve compression retention, and maintain proper engine operation under towing, daily driving, and performance diesel conditions.
Cummins OEM valve seat inserts are manufactured to strict factory specifications for fitment, hardness, durability, and thermal transfer characteristics to ensure long-term reliability in demanding diesel applications.
FEATURES
- Genuine Cummins OEM exhaust valve seat insert
- Fits 1989-1998 5.9L Cummins 12-valve engines
- Precision-machined hardened steel construction
- Restores proper valve sealing and seat geometry
- Designed for OEM cylinder head specifications
- Helps improve compression retention and durability
- Ideal for cylinder head rebuilding and repair
- Direct replacement for worn or damaged valve seats
FITMENT
- 1989-1993 Dodge Ram D/W250 & D/W350 5.9L Cummins 12V
- 1994-1998 Dodge Ram 2500/3500 5.9L Cummins 12V
- Fits OEM 12-valve Cummins cylinder heads
Fitment Note: Professional machine shop installation is recommended for valve seat replacement and cylinder head machining.
WHAT'S INCLUDED
- 1 Cummins 3904105 OEM exhaust valve seat insert
CROSS-REFERENCE & RELATED PRODUCTS
- CUMMINS 3903513 OEM INTAKE VALVE SEAT INSERT
- CUMMINS 3902460 OEM EXHAUST VALVE
- CUMMINS 3901117 OEM INTAKE VALVE
- HAMILTON CAMS 12V VALVE SPRINGS
- CUMMINS OEM ENGINE COMPONENTS
WHY REPLACE EXHAUST VALVE SEATS?
Exhaust valve seats are subjected to constant thermal cycling and combustion pressure. Over time, valve seats can wear, crack, or recede into the cylinder head, causing compression loss, poor valve sealing, excessive heat buildup, and reduced engine performance. Replacing worn valve seats during cylinder head service helps restore proper engine operation and long-term reliability.
SPECIFICATIONS
| Specification | Details |
|---|---|
| Manufacturer | Cummins |
| Part Number | 3904105 |
| Component Type | Exhaust valve seat / valve insert |
| Engine Compatibility | 5.9L Cummins 12V |
| Fitment Years | 1989-1998 |
| Material | OEM hardened steel alloy |
| Application | Cylinder head rebuilding and repair |
| Condition | New Genuine Cummins OEM Part |
| Prop 65 | Warning: Cancer and Reproductive Harm — www.P65Warnings.ca.gov. |
FAQ
What does the Cummins 3904105 valve seat fit?
Cummins 3904105 is an OEM exhaust valve seat insert designed for 1989-1998 5.9L Cummins 12-valve diesel cylinder heads.
Why replace exhaust valve seats during a rebuild?
Replacing worn or damaged valve seats helps restore proper valve sealing, improve compression retention, and maintain cylinder head reliability under high combustion temperatures.
Is this a genuine Cummins OEM component?
Yes. Cummins 3904105 is a genuine OEM exhaust valve seat insert manufactured to factory Cummins specifications.
Should valve seat installation be performed by a machine shop?
Yes. Professional machine shop installation is recommended because cylinder head machining and proper seat installation procedures are critical for correct fitment and durability.
