Product Description
Cummins 3946849 — 190° Coolant Thermostat
MPN: 3946849 | Also Known As: engine thermostat | Opening Temp: 190°F (88°C)
Why This Part
- ✓ OE temperature control for proper warm-up and stable operating temps.
- ✓ Direct-fit for 2nd-Gen Ram 5.9L ISB (verify by VIN/ESN).
- ✓ Helps prevent overheating or extended warm-up from a sticking thermostat.
- ✓ Built to Cummins material specs for long service life.
Quick Specs
| Type | Engine coolant thermostat |
|---|---|
| OE Part # | 3946849 |
| Opening Temp | 190°F (88°C) |
| Includes | Thermostat only; seal & housing gaskets sold separately |
| Qty Required | 1 per engine (sold individually) |
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1998.5–2002 | 5.9L ISB (24-Valve, VP44) | Ram 2500/3500 |
Industrial/Off-Highway: Common across B-Series/ISB/QSB families (4B/6B/5.9/6.7 variants). Always confirm by ESN.
Compatibility Notes: 1994–1998 12-valve trucks typically use the 180° thermostat 3928499. Some retailers list 3946849 for 2000–2002 only—verify by VIN/ESN.
Often Paired With
- Thermostat seal (O-ring): Cummins 3925466 (rectangular ring)
- Thermostat housing cover gasket: Cummins 3933325 (12V cover style)
- Fresh coolant per OEM spec after service
What’s In The Box
- (1) Genuine Cummins 190° Thermostat (3946849)
- Seals/gaskets sold separately (see “Often Paired With”).
Install Tips
- Drain coolant to below thermostat level; clean mating surfaces.
- Always use a new seal; torque housing fasteners to spec.
- Refill/bleed per factory procedure and verify fan & heater operation.
FAQ
WILL THIS FIT MY 1998.5–2002 5.9L CUMMINS RAM?Yes—3946849 is the OE 190° thermostat for 1998.5–2002 24-valve (VP44) 5.9L Ram 2500/3500. Always confirm by VIN/ESN.
DOES THE THERMOSTAT INCLUDE THE SEAL?Most listings are thermostat only. We recommend adding seal 3925466 and replacing any housing gasket as needed.
WHAT’S THE DIFFERENCE BETWEEN 180° AND 190° THERMOSTATS?’94–’98 12-valve typically runs 180° (3928499), while ’98.5–’02 24-valve uses this 190° unit for faster warm-up and emissions strategy.
IS THIS A GENUINE CUMMINS PART?Yes—OE Cummins 3946849 built to factory materials and calibration.
SHOULD I CHANGE COOLANT AFTER REPLACEMENT?Top up at minimum; if coolant is old/contaminated, flush and refill with the correct spec.
