Product Description
Cummins 3905401 OEM Expansion Plug (Side) – Ram 5.9L/6.7L Cummins (2003–2018)
The Cummins 3905401 OEM Expansion Plug (Side) is a genuine Cummins engine block sealing component designed for 2003–2018 Ram trucks equipped with the 5.9L and 6.7L Cummins diesel engine. Manufactured to Cummins OE specifications, this steel expansion plug provides a precise interference fit to help prevent coolant leaks, maintain cooling system integrity, and protect the engine block from corrosion-related failures.
Whether you're repairing a leaking freeze plug, performing preventative maintenance, or completing a full engine rebuild, the Cummins 3905401 expansion plug delivers the quality, durability, and fitment expected from a genuine OEM Cummins replacement part. Unlike many aftermarket alternatives, this OE plug is engineered specifically for Cummins block casting dimensions to ensure proper sealing performance.
Features
- Genuine Cummins OEM expansion plug
- Direct replacement for Cummins part number 3905401
- Designed for side engine block expansion plug locations
- Helps prevent coolant leaks and pressure loss
- Precision-engineered interference-fit design
- High-quality steel construction
- Ideal for engine repairs and rebuilds
- Protects against coolant seepage and corrosion-related failures
- OE fit, function, and reliability
- Trusted Cummins factory replacement component
Fitment
- 2003–2007 Dodge Ram 2500/3500 5.9L Cummins
- 2007.5–2018 Ram 2500/3500 6.7L Cummins
- ISB 5.9L Cummins engines
- ISB 6.7L Cummins engines
- Side engine block expansion plug locations
- Engine rebuild and maintenance applications
Note: Always verify engine serial number (ESN) and application requirements before ordering. Expansion plug location and quantity may vary by engine configuration.
What's Included
- One Genuine Cummins 3905401 Expansion Plug
Specifications
- Manufacturer: Cummins Genuine Parts
- Part Number: 3905401
- Product Type: Expansion Plug
- Location: Side Engine Block
- Material: Steel Construction
- Design: Interference-Fit Expansion Plug
- Engine Compatibility: 5.9L and 6.7L Cummins
- Application: Coolant System Block Sealing
- Fitment: 2003–2018 Ram Cummins Applications
- Cooling System Function: Maintains Proper Coolant Sealing
- OEM Status: Genuine Cummins Replacement Part
Cross Reference Numbers
3905401, M3905401, M-3905401
FAQ
What does the Cummins 3905401 expansion plug do?
The expansion plug seals openings in the engine block and helps maintain proper coolant system integrity by preventing leaks and pressure loss.
Is the Cummins 3905401 the same as a freeze plug?
Yes. Expansion plugs are commonly referred to as freeze plugs or core plugs and are used to seal casting openings in the engine block.
Should expansion plugs be replaced during an engine rebuild?
Yes. Many engine builders recommend replacing all expansion plugs during a rebuild to help prevent future coolant leaks and corrosion-related failures.
Is sealant required during installation?
Most technicians apply a light coolant-safe sealant during installation, although the plug is engineered to seal through an interference fit. Always follow Cummins service procedures.
Is this a genuine Cummins part?
Yes. The 3905401 is a genuine OEM Cummins expansion plug designed to meet factory fitment and sealing specifications.
Will this fit both 5.9L and 6.7L Cummins engines?
Yes. This plug is commonly used on 2003–2018 Ram applications equipped with 5.9L and 6.7L Cummins diesel engines. Verify fitment by ESN when possible.
