Description
PAI Industries 181841 bypass-style engine coolant thermostat for Cummins 855 family engines (NH855, NT855, NTA855, NTC855, Big Cam I–IV, and 855 LFC). Opens at 187°F (86°C) to regulate coolant flow between block and radiator. Aftermarket replacement for Cummins 3064455 (with supersessions 3039395 and 3061500). Ships with the housing gasket required for installation.
Signs You Need a New Thermostat
- Engine overheating under load
- Slow warm-up or never reaching normal operating temperature
- Erratic coolant-temp gauge swings
- Weak cab heat output
Specifications
| Manufacturer | PAI Industries |
|---|---|
| Part Number | 181841 |
| Part Type | Engine Coolant Thermostat (bypass) |
| Opening Temperature | 187°F (86°C) |
| Engine Compatibility | Cummins 855 family (NH855, NT855, NTA855, NTC855, Big Cam I–IV, 855 LFC) |
| Gasket Included | Yes |
Cross References
This part replaces or is equivalent to the following part numbers:
- Cummins: 3064455, 3039395, 3061500
- Interstate McBee: M-3064455, M-3039395
Applications
This thermostat fits the following Cummins engines:
- Cummins NH855 / NT855 / NTA855 / NTC855 (1970s–1990s on-highway)
- Cummins Big Cam I, II, III, IV (1976–1985)
- Cummins 855 LFC (Low Fuel Consumption) (1985–1990s)
- Cummins 88NT with idler
Representative vehicles using these engines:
- Freightliner FLD, FLC, Classic
- Kenworth W900, K100, T800
- Peterbilt 379, 359, 362, 377
- International 9670, 9370, Paystar
- Mack R-Model, Superliner
- Western Star 4900-series
- Versatile, Steiger, Big Bud agricultural tractors and industrial gensets
Verify engine serial number and CPL before ordering — cold-climate / different operating-temp builds use 160°F (PAI 181840) or 170°F variants.
