Mishimoto MMTS-RAM-94L Low-Temp Thermostat for 1994-1998 Dodge Ram 2500/3500 5.9

Vehicle Fitment

• 1994-1998 Dodge Ram 2500 (Base, ST, SLT, Laramie, 5.9L Cummins Turbo Diesel, 2WD/4WD)
• 1994-1998 Dodge Ram 3500 (Base, ST, SLT, Laramie, 5.9L Cummins Turbo Diesel, 2WD/4WD, SRW/DRW)

Fitment Notes

• Fits the 2nd Generation 5.9L Cummins turbocharged inline-six diesel engine (12-valve and 24-valve variants) found in 1994-1998 Dodge Ram 2500 and 3500 trucks.
• This is a Cummins diesel-specific thermostat - does not fit the 5.9L Magnum gasoline V8 engine found in Ram 1500/2500 gas models of the same era.
• Does not fit 1999 and later Cummins applications - for 1999-2013 5.9L/6.7L Cummins, use Mishimoto MMTS-RAM-99L.
• Designed to fit the stock thermostat housing - no housing replacement required.
• Compatible with both stock and upgraded cooling systems including aftermarket radiators.

Features

• Lower activation temperature of 174°F (79°C) versus OEM activation at 180°F (82°C) - coolant circulates earlier, reducing and maintaining lower engine operating temperatures.
• Ideal for warm and hot climates where the factory thermostat allows engine temperatures to climb too high under towing, hauling, or hard driving conditions.
• Recommended for 5.9L Cummins trucks running performance modifications such as injector upgrades, increased boost, or aggressive fueling tunes that generate additional heat.
• Direct-fit OEM replacement designed for installation into the stock thermostat housing with no modifications required.
• Constructed from high-quality copper alloy and stainless steel for long-term durability and corrosion resistance in a diesel engine environment.
• Standard-flow design ensures full, unrestricted coolant flow through the engine circuit once the activation temperature is reached.
• Helps reduce thermal stress on head gaskets, cooling passages, and turbocharger components during sustained high-load operation.
• Backed by Mishimoto's Lifetime Warranty for complete peace of mind.

Specifications

• Part Number: MMTS-RAM-94L
• UPC: 748354013948
• Mishimoto Activation Temperature: 174°F (79°C)
• OEM Activation Temperature: 180°F (82°C)
• Thermostat Flow Rate: Standard-Flow
• Construction Materials: Copper Alloy / Stainless Steel
• Engine Application: Dodge 5.9L Cummins Turbo Diesel Inline-Six (2nd Gen, 12-valve and 24-valve)
• Fitment Type: Direct OEM Replacement
• Installation Position: Engine coolant circuit, fits stock thermostat housing
• Package Dimensions: 2.55" x 2.55" x 2.55"
• Shipping Weight: 1.0 lb

Included Components

• 1x Mishimoto Low-Temperature Thermostat (MMTS-RAM-94L)

Product Description

The Mishimoto MMTS-RAM-94L is a low-temperature direct-fit thermostat engineered specifically for 1994-1998 Dodge Ram 2500 and 3500 trucks equipped with the 5.9L Cummins turbocharged diesel engine - covering both 12-valve (1994-1998) and 24-valve (1998) variants of the second-generation platform. The Mishimoto thermostat opens at 174°F compared to the factory unit's 180°F threshold, allowing coolant to begin flowing through the engine sooner and maintaining a consistently lower operating temperature. This 6°F reduction in activation point delivers measurable thermal headroom for trucks used in warm climates, heavy towing, payload hauling, or modified diesel applications where the stock cooling system is pushed to its limits.

The 5.9L Cummins is a legendary diesel engine, but its relatively tight factory temperature tolerances mean that sustained high-load operation - particularly in hotter ambient conditions - can stress head gaskets, cooling passages, and the injection system. The MMTS-RAM-94L addresses this proactively by circulating coolant earlier in the warm-up cycle, preventing heat buildup before it becomes a problem. Installation is a simple, direct bolt-in process using the factory thermostat housing. No modifications, adapters, or additional parts are required. The thermostat is machined from copper alloy and stainless steel, providing the corrosion resistance and durability expected in a long-service diesel application.

For owners running performance injectors, increased fuel delivery, compound turbos, or any modification that raises engine heat output above stock levels, the MMTS-RAM-94L is a cost-effective foundational upgrade. It pairs well with the Mishimoto 5.9L Cummins aluminum radiator and silicone hose kit for a complete first- and second-generation cooling system overhaul. All components are backed by Mishimoto's Lifetime Warranty.