Product Description
The CUMMINS 3954829 OEM THERMOSTAT HOUSING SEAL is the genuine O-ring that seals the thermostat to the housing on 2003–2018 Ram 5.9L and 6.7L ISB engines, restoring a leak-free joint and stable coolant temps. This OE elastomer seal is engineered by Cummins to handle repeated heat cycles, modern coolants, and long service intervals without hardening, shrinking, or cracking – cheap aftermarket rings can’t match the durability or precise fit of a factory part.
FITMENT
- 2003–2007 Dodge/Ram 2500 & 3500, 5.9L ISB (24V common-rail)
- 2007.5–2018 Ram 2500, 3500, 4500 & 5500, 6.7L ISB
- Other Cummins B/ISB/QSB 5.9L & 6.7L applications that specify part number 3954829 (verify by ESN)
Always confirm by VIN or engine serial number (ESN) and a Cummins parts catalog before ordering.
KEY FEATURES
- Genuine Cummins 3954829 thermostat housing seal (O-ring)
- Maintains a coolant-tight seal between thermostat, housing, and engine
- Resists coolant additives, corrosion, and high under-hood temperatures
- Direct-fit for Ram 5.9L/6.7L ISB cooling systems – no trimming or adapting
- Low-cost insurance against leaks when servicing thermostats or housings
INSTALL NOTES
- Clean all mating surfaces thoroughly – remove old gasket material and corrosion.
- Lightly lubricate the O-ring with clean coolant before installation.
- Do not over-tighten housing bolts; follow factory torque specs and pattern.
- Refill and bleed the cooling system; confirm no seepage at operating temperature.
CROSS-REFERENCE & RELATED CUMMINS PRODUCTS
- Pairs with 180° thermostat: CUMMINS 5292742 OEM 180° THERMOSTAT – 5.9L ISB (1998.5–2007)
- Pairs with 190° thermostat: CUMMINS 5292744 OEM 190° THERMOSTAT – 5.9L ISB (2003–2007)
Aftermarket ID only (not sold under Cummins brand): Interstate-McBee M-3954829, PAI 136095. Use for identification or cross-checking; always order genuine CUMMINS 3954829 on this page when OEM is required.
WHAT’S IN THE BOX
- (1) Genuine Cummins thermostat housing seal – P/N 3954829
Specifications for cummins 3954829
| Field | Value |
|---|---|
| Brand | Cummins Genuine OEM |
| Part Number | 3954829 |
| Part Type | Thermostat housing seal (O-ring) |
| Engine Compatibility | 5.9L & 6.7L ISB Cummins (select B/ISB/QSB engines using 3954829) |
| Primary Vehicle Fitment | 2003–2018 Ram 2500/3500/4500/5500 5.9L & 6.7L Cummins |
| UPC | Not published by Cummins |
| GTIN | Not published by Cummins |
| Cross Reference (ID only) | Interstate-McBee M-3954829; PAI 136095 (aftermarket equivalents) |
| E-Codes / Emissions | Not applicable (service seal – cooling system) |
| Shipping Weight | Approx. 0.01 lb total packaged weight |
| Shipping Dimensions | Approx. 2.25" × 2.25" × 0.13" (single seal package) |
| Country of Origin | Not specified by manufacturer |
| Prop 65 Warning | This product may expose you to chemicals known to the State of California to cause cancer or reproductive harm. More info: www.P65Warnings.ca.gov |
FAQ
WILL THIS FIT MY 5.9L OR 6.7L CUMMINS RAM?
Yes. CUMMINS 3954829 is the OE thermostat housing seal used on most 2003–2018 Ram 2500/3500/4500/5500 trucks with 5.9L or 6.7L ISB engines, as long as the parts catalog for your VIN/ESN specifies 3954829. Always verify by VIN or ESN to confirm coverage.
IS THIS AN O-RING OR A FLAT GASKET?
This part is an O-ring style seal. It sits in a machined groove between the thermostat and housing, sealing the coolant passage when the housing is bolted down.
SHOULD I REPLACE THIS SEAL WHEN I CHANGE THE THERMOSTAT?
Yes. Any time you remove the thermostat or housing, you should install a new seal. Re-using old O-rings is a common cause of coolant seepage and come-backs after a thermostat job.
DO I NEED TO USE RTV OR SEALANT WITH THIS OEM O-RING?
In most applications, no extra sealant is required – the Cummins O-ring seals on clean, undamaged surfaces. Follow your Cummins service manual for ESN-specific instructions and torque specs.
WHICH CUMMINS THERMOSTATS DOES THIS SEAL WORK WITH?
This seal is commonly paired with Ram 5.9L thermostats like CUMMINS 5292742 (180°) and CUMMINS 5292744 (190°), along with other Cummins thermostats that call for 3954829 in the parts catalog.
IS THIS A GENUINE CUMMINS PART OR AFTERMARKET?
This listing is for a genuine CUMMINS 3954829 seal in OEM packaging. Aftermarket numbers such as Interstate-McBee M-3954829 and PAI 136095 are listed only as cross-reference IDs.
