Mishimoto high-temperature thermostat for the 1989-1993 first-gen Dodge D250 / D350 / W250 / W350 5.9L 12-valve Cummins diesel. Its higher 189.5°F activation (vs. the 180°F factory unit) restricts coolant circulation longer for a quicker engine warm-up — ideal for cold climates where rapid warm-up and cabin heat matter. Includes a replacement gasket, backed by the Mishimoto Lifetime Warranty.
| Type | High-temperature thermostat |
| Activation Temp | 87.5°C / 189.5°F (vs. 180°F stock) |
| Engine | 5.9L 12-valve Cummins diesel |
| Includes | Replacement gasket |
| Application | 1989-1993 Dodge D/W250-350 5.9L Cummins |
| Part Number | MMTS-RAM-89H |
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 1989-1993 | Dodge | D250 | Base |
| 1989-1993 | Dodge | D350 | Base |
| 1989-1993 | Dodge | W250 | Base |
| 1989-1993 | Dodge | W350 | Base |
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