Product Description
Interstate-McBee M-3954829 Thermostat Housing Seal – 03–18 5.9L/6.7L Cummins
High-quality aftermarket replacement thermostat housing seal (O-ring) engineered to OEM dimensions for 2003–2018 5.9L & 6.7L Cummins ISB engines. Restores a leak-free seal between the thermostat and housing to maintain correct operating temperature and cooling system performance.
- Direct replacement: OEM-equivalent form/fit/function for Cummins 3954829.
- Stop coolant weeping: Proper crush and sealing profile to prevent leaks at the thermostat interface.
- Service best practice: Replace the seal any time you remove or replace the thermostat.
- Aftermarket value: Interstate-McBee quality at a lower cost than OEM-boxed parts.
Specifications
| Interstate-McBee P/N | M-3954829 |
|---|---|
| OEM Cross-Reference | Cummins 3954829 |
| Type | Thermostat housing seal (O-ring) |
| Position | Seals thermostat to housing/engine block |
| Compatibility | Cummins ISB 5.9L & 6.7L (see fitment) |
Vehicle Fitment
Always verify by engine serial number (ESN) or VIN when possible.
- Dodge Ram 2500/3500 – 5.9L Cummins (ISB)
- Model Years: 2003–2007
- Dodge/Ram 2500/3500/4500/5500 – 6.7L Cummins (ISB)
- Model Years: 2007.5–2018
Install Notes
- Clean both sealing grooves/surfaces; remove all old rubber and deposits.
- Lightly lubricate the new O-ring with coolant-safe lubricant; do not over-stretch.
- Follow the Cummins service manual for torque sequence and specs on the housing fasteners.
What’s Included
- (1) Thermostat housing seal (O-ring), M-3954829
Why Buy From CPP Diesel
- ESN-verified fitment support from real diesel techs
- Fast shipping, easy returns
- Curated Cummins cooling-system parts for complete service jobs
FAQ
Will this fit both 5.9L and 6.7L Cummins engines?Yes. This seal is listed for 2003–2018 Dodge/Ram models with 5.9L or 6.7L Cummins ISB engines. Verify by ESN for edge cases.
Is it an O-ring or a paper gasket?
It is a molded O-ring style seal that sits in the thermostat/housing groove to create the seal.
Do I need to replace this every time I change the thermostat?
Yes. Reusing a compressed or heat-cycled seal can cause leaks. Replace it any time the thermostat is serviced.
Does it work with aftermarket billet thermostat housings?
In most cases yes, if the housing is designed to OE dimensions. Check the housing manufacturer’s notes for seal compatibility.
Should I use sealant on the O-ring?
No sealant is typically required or recommended on O-ring thermostat seals. Install clean and lightly lubricated only.
Product Videos
Custom Field
YEAR 2003-2018
MAKE DODGE
ENGINE 5.9L,6.7L
