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Mishimoto

Mishimoto Dodge 5.9L/6.7L Cummins High-Temperature Thermostat

SKU: MMTS-RAM-99H

$83.95

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A defective thermostat can result in engine overheating and potential internal damage. Improve the reliability of your 5.9L/6.7L cooling system with a Mishimoto Dodge 5.9L/6.7L Cummins High-Temperature Thermostat! This thermostat is designed as a direct-fit replacement for your aged factory unit. The Mishimoto thermostat has a higher activation temperature (205 degrees Fahrenheit) compared to the factory thermostat (190 degrees Fahrenheit for 99-10 and 2013 trucks and 200 degrees Fahrenheit for 10-12 trucks). The higher activation temperature restricts coolant flow longer to allow a quicker engine warm-up, making this thermostat ideal for use in cold climates. As with all our products, this thermostat includes the Mishimoto Lifetime Warranty, ensuring superior product quality and craftsmanship.
Engine coolant thermostat designed to regulate coolant flow and maintain optimal operating temperature. Ensures efficient warm-up, prevents overheating, and supports reliable performance with a precise fit.
1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 42RE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 42RE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 42RE, 2003 Dodge Ram 1500 Laramie 5.9 Liter 45RFE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 2003 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 2003 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 2003 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 2003 Dodge Ram 1500 Laramie 5.9 Liter 46RE, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV3500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 1999-2001 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 2003 Dodge Ram 1500 Laramie 5.9 Liter NV4500, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter 45RFE, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter 45RFE, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter 46RE, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter 46RE, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter NV3500, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter NV3500, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter NV4500, 2002-2003 Dodge Ram 1500 SLT 5.9 Liter NV4500, 1999-2001 Dodge Ram 1500 Sport 5.9 Liter 42RE, 1999-2001 Dodge Ram 1500 Sport 5.9 Liter 42RE, 1999-2001 Dodge Ram 1500 Sport 5.9 Liter 42RE, 1999-2001 Dodge Ram 1500 Sport 5.9 Liter 46RE, 1999-2001 Dodge Ram 1500 Sport 5.9 Liter 46RE ...See Application Guide for Additional Fitments


  • Restricts coolant system circulation for longer time to provide quicker warm up

  • Mishimoto Lifetime Warranty

  • Ideal for cool climates

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