Mishimoto MMTS-4RUN40-03 Low-Temperature Racing Thermostat and Housing for Toyota 4Runner 4.0L

A defective thermostat can result in engine overheating and potential internal damage. Improve the reliability of your 2003-2024 Toyota 4Runner 4.0L cooling system with a Mishimoto Low-Temperature Racing Thermostat and housing! This thermostat is designed as a direct-fit replacement for your aged stock unit. The Mishimoto thermostat has a lower activation temperature (71?C/160?F) compared to the factory thermostat (82?C/180?F). The lower activation temperature allows coolant to flow through the engine earlier, which reduces and maintains lower engine temperatures. This thermostat is ideal for use in warmer climates, on vehicles making more power than stock, or under extreme towing/driving conditions. The stock-style housing will provide a proper seal and installs easily. Like all our Toyota Performance parts, this thermostat and housing includes the Mishimoto Lifetime Warranty. 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.

• The lower activation temperature allows coolant to flow through the engine earlier, which reduces and maintains lower engine temperatures. (71C/160F compared to the factory thermostat at 82C/180F)
• Ideal for use in hot climates, on modified vehicles, or in extreme towing/driving conditions
• Stock-style housing includes pre-installed low-temperature thermostat for easy install

Improve cooling-system control in your Toyota 4Runner 4.0L with the Mishimoto MMTS-4RUN40-03 Low-Temperature Racing Thermostat and Housing. Designed as a direct-fit replacement for the original thermostat assembly, this stock-style unit supports reliable installation and helps maintain lower engine temperatures in demanding driving conditions. It is compatible with select 2003–2024 Toyota 4Runner 4.0L applications and is also suited to vehicles used in warm climates, under heavy towing loads, or with performance modifications.
The Mishimoto low-temperature thermostat activates at 160°F, allowing coolant to begin circulating through the engine earlier than the factory thermostat, which typically opens at 180°F. Earlier coolant flow can help reduce and stabilize operating temperatures when the vehicle is working hard. The thermostat is engineered to regulate coolant flow during warm-up and normal operation, supporting efficient engine performance while helping protect against excessive heat.
The assembly includes a pre-installed thermostat in a stock-style housing for a straightforward replacement process and a proper seal. Its precise fit helps simplify installation while restoring dependable temperature regulation to an aging or defective cooling-system component. Like other Mishimoto Toyota Performance parts, the MMTS-4RUN40-03 is backed by the Mishimoto Lifetime Warranty for lasting confidence.

• Lower 160°F activation temperature promotes earlier coolant flow than the factory 180°F thermostat


• Helps reduce and maintain lower engine temperatures during demanding operation


• Ideal for hot climates, modified vehicles, towing, and extreme driving conditions


• Stock-style housing includes a pre-installed low-temperature thermostat for easier installation


• Direct-fit replacement for select 2003–2024 Toyota 4Runner 4.0L applications


• Backed by the Mishimoto Lifetime Warranty

Features:

• 160°F low-temperature activation supports earlier coolant circulation and lower operating temperatures

• Designed for hot climates, modified vehicles, towing, and demanding driving conditions

• Stock-style housing with pre-installed thermostat simplifies installation

• Direct-fit replacement for select 2003–2024 Toyota 4Runner 4.0L models

• Mishimoto Lifetime Warranty included

Compatible With
2003 Toyota 4Runner
2004 Toyota 4Runner
2005 Toyota 4Runner
2005 Toyota Tacoma
2005 Toyota Tundra
2006 Toyota 4Runner
2006 Toyota Tacoma
2006 Toyota Tundra
2007 Toyota 4Runner
2007 Toyota FJ Cruiser
2007 Toyota Tacoma
2007 Toyota Tundra
2008 Toyota 4Runner
2008 Toyota FJ Cruiser
2008 Toyota Tacoma
2008 Toyota Tundra
2009 Toyota 4Runner
2009 Toyota FJ Cruiser
2009 Toyota Tacoma
2009 Toyota Tundra
2010 Toyota 4Runner
2010 Toyota FJ Cruiser
2010 Toyota Tacoma
2010 Toyota Tundra
2011 Toyota 4Runner
2011 Toyota FJ Cruiser
2011 Toyota Tacoma
2011 Toyota Tundra
2012 Toyota 4Runner
2012 Toyota FJ Cruiser
2012 Toyota Tacoma
2012 Toyota Tundra
2013 Toyota 4Runner
2013 Toyota FJ Cruiser
2013 Toyota Tacoma
2013 Toyota Tundra
2014 Toyota 4Runner
2014 Toyota FJ Cruiser
2014 Toyota Tacoma
2014 Toyota Tundra
2015 Toyota 4Runner
2015 Toyota Tacoma
2016 Toyota 4Runner
2017 Toyota 4Runner
2018 Toyota 4Runner
2019 Toyota 4Runner
2020 Toyota 4Runner
2021 Toyota 4Runner
2022 Toyota 4Runner
2023 Toyota 4Runner
2024 Toyota 4Runner